Building Regulations & Design Guidelines- Structural

BUILDING REGULATIONS

& DESIGN GUIDELINESSTRUCTURAL

Department of Planning and Development Development - TRAKHEES Ports, Customs & Free Zone Corporations Government of Dubai, United Arab Emirates

BUILDING REGULATIONS & DESIGN GUIDELINES- STRUCTURAL

First Edition-2011

Prepared & Issued by

Department of Planning and Development - TRAKHEES Ports, Customs & Free Zone Corporation Government of Dubai, United Arab Emirates Email: accreditation@trakhee [email protected] s.ae Website: www.trakhees.ae

BUILDING REGULATIONS & DESIGN GUIDELINESSTRUCTURAL 1st Edition-2011

This edition issued in October, 2011 Dubai, United Arab Emirates

All rights reserved to Department of Planning and Development – TRAKHEES - Ports, Customs & Free Zone Corporation (PCFC) Government of Dubai, United Arab Emirates (UAE). No parts of this publication may be reproduced, stored in any retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior consent of the copyright owner. These regulations and guidelines have been established to be applied within Trakhees - PCFC Jurisdiction. Implementation of these regulations out of Trakhees jurisdiction is the sole responsibility of the concerned parties, whereby the local authority regulations shall be precedent and govern.

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Department of Planning and Development - TRAKHEES Ports, Customs & Free Zone Corporations Government of Dubai, United Arab Emirates

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ACKNOWLEDGEMENT

T

he publication of this book could not have been possible without the ungrudging efforts put in by a number of individuals working in ALL sections of the Department of Planning and Development TRAKHEES. We would like to thank the Section Managers and their respective teams for their meticulous effort in maintaining the Content, Structure and Quality of the book. We also wish to acknowledge contributions made by PCFC legal department, Consultants and Engineers from different organizations; and lastly, to Dubai Municipality and to other International Organizations in the field of Construction whose publications and articles in terms of local and international standards are frequently used. In addition, our sincere thanks to all those who contributed their comments, feedback, and suggestions, which have all been considered in this edition. As there is always room for improvement, Trakhees will continuously welcome comments/suggestions on this Book, and will consider all that are received. Your comments will continue to improve this book leading to its ultimate acceptance. As always, it has been a great joint effort.

Eng. Nazek Al Sabbagh Managing Director Trakhees - Ports, Customs & Free Zone Corporation

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TABLE OF CONTENTS

SECTION 1:

TABLE OF CONTENTS

GEOTECHNICAL GUIDELINES & REGULATIONS 1.1 1.2 1.3

Introduction......................................................................................12 Basic Guidelines For Soil Investigation Report..................................12 Recommendations To Be Included In The Soil InvestigationReport.........................................................................27 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7 1.3.8 1.3.9

1.4

SECTION 2:

3.4 3.5 3.6

Introduction.....................................................................................64 Design Outcome..............................................................................64 Sustainability And Environmentally Responsible Design.................64 Applicable Codes.............................................................................65 2.4.1 2.4.2 2.4.3 2.4.4

2.5

4.1 4.2

2.6 2.7

Introduction...................................................................................110 Applicable Codes...........................................................................110 4.2.1 4.2.2 4.2.3 4.2.4

4.3

4.4

Dead And Live Loads....................................................110 Seismic Loads...............................................................111 Wind Load.....................................................................111 Design Codes.................................................................111

Performance Criteria - Analysis, Design And Detailing..................................................................................111 4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8

Dead And Live Loads.......................................................65 Seismic Loads...............................................................65 Wind Loads....................................................................65 Design Codes.................................................................66

Design Life....................................................................66 Computer Models, Structural Analysis And Design Requirements....................................................66

Pre Cast Specialist Registration.....................................92 Pre Cast Design Guidelines............................................94 Documents Required For Obtaining Precast Structure Permit...........................................................106

STRUCTURAL DESIGN GUIDELINES – STEEL STRUCTURES

Performance Criteria........................................................................66 2.5.1 2.5.2

Software Approval.........................................................86 Design Guidelines..........................................................86

General Notes For Specialist & System Approval.............................91 Documents Required For Obtaining Prestress Permit......................92 Guidelines For Pre Cast Concrete Works..........................................92 3.6.1 3.6.2 3.6.3

SECTION 4:

Approval Of Materials....................................................81 Registration Of Pt Specialist..........................................84 Storage Of Materials......................................................85 Approval Of Method Statement.....................................85 Permission To The First Project......................................85

Software Approval & Design Guidelines..........................................86 3.3.1 3.3.2

STRUCTURAL DESIGN GUIDELINES – BUILDING STRUCTURES 2.1 2.2 2.3 2.4

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3.3

Soil Improvement..........................................................36 Safety Against Liquefaction............................................47 Calculation Theory.........................................................48 Evaluation Of Likely Liquefaction Induced Hazards.......49 Lateral Extend of Ground improvement..........................51

Design Criteria For Piling Works.....................................56 Points To Be Checked During Construction....................59 PilesTesting...................................................................61

General............................................................................................80 Pre Stressed Concrete Systems Approval.........................................81 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5

Excavation Works..........................................................27 Open Excavation And Protection....................................27 Backfill Materials And Compaction Criteria....................28 Retaining Structures......................................................28 Dewatering....................................................................29 Shallow Foundations.....................................................34 Pile Foundations............................................................34 Foundation Concrete.....................................................35 Liquifaction...................................................................35

Shorting Guidelines..........................................................................51 Design Guidelines For Building Piles.................................................56 1.6.1 1.6.2 1.6.3

GUIDELINES FOR PRE STRESSED & PRECAST CONCRETE WORKS (SLABS) 3.1 3.2

Soil improvement Guidelines...........................................................36 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5

1.5 1.6

SECTION 3:

General.........................................................................112 Loading.........................................................................113 Limit State Of Strength.................................................113 Limit State Of Serviceability.........................................114 Foundation...................................................................116 Holding Down Bolts......................................................116 Fatigue.........................................................................116 Structural Integrity.......................................................117

General Guidelines For Industrial Steel Structures..............................................................................119

Structural Calculations.....................................................................72 Structural Drawings.........................................................................73

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INTRODUCTION

T

he main principles of the structural buildings design guidelines were released first time in 2006, as set out in Chapter 25 amongst the CED-Blue Code. These guidelines were aiming to provide the structural engineers with the general and minimum requirements for very limited structures; and the weak point was being not extended to cover all types of structural developments in terms of geometry and construction materials. Trakhees-CED, in its ongoing and incessant communication with engineering community, have received an adequate encouragements to go further in producing separate volume for structural design guidelines that can tackle all the common structural industry. Through the past year, a comprehensive and oriented effort have been offered to establish a set of guidelines that providing bases of analysis and design as well as the required documents for submissions to meet the needs of approvals for residential, commercial and industrial buildings, whether being made of concrete, steel or pre stressed materials through a set of unified consistence and compatible rules. The information contained in this volume has been also compiled for use, guidance since proposing the structure scheme, interpretation of geotechnical data, computer modeling, loading, analysis and design. It is also providing the designers with the basic requirements for review and checking of the design documents with CED team from the submission time until the approval that will facilitate and ease the permits issuance. It is anticipated that the use of these guidelines will result in a uniform design and construction of buildings throughout all types of structures.

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GEOTECHNICAL GUIDELINES & REGULATIONS

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01 SECTION

11

N O I T C E S

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1.1


SECTION: 1


location with specified coordinates as per affection plan and geographical maps from the concerned authorities and also with relevant to the information about magnitude of superimposed loads, number of floors, shape of structure, past land use, surface topography, geological features and surface drainage.

INTRODUCTION These Design Guidelines & Regulations are intended to provide minimum geotechnical design requirements for RC buildings foundations and substructures to safeguard life or limb, environment, property and public welfares. Submission for no objection certificates for different types of applications by consultants to be as per this guidelines to avoid any delay for the project or abortive work to the CED part. Incomplete submissions will be returned without review and as such CED shall not be responsible for any delays to the project accordingly. CED reserves the right to levy additional appraisal fees for checking the incomplete and unchecked submissions noting that this fee shall be paid by the consultant and not to be passed on to the client.

1.2.2

To specify the number of boreholes (one borehole for each 750 m2 for structures small in plane area, exploration should be made at a minimum of three points). For structures of moderate size, it is customary and satisfactory to anticipate making five boreholes, one at each corner and one deeper at the centre or under the core area. In case of structures covering a large area, the exploration points may be placed in a grid. The mutual distance between the boreholes points that considered an ap-

The Guidelines are aimed to give the designers, geotechnical engineers, specialist contractors and inspectors a general idea of the basic requirements for review and checking the structures schemes until approval from the CED according to principles and standards in order to facilitate and speed the completion of the work efficiently. It is anticipated that the use of these guidelines will result in a uniform design and construction of buildings throughout DW projects. Any requests for revisions must be fully documented and presented to the Civil Engineering Department for review and acceptance prior to any work commencement. These guidelines are provided as a ref erence and may not be taken as authority to construct without prior review. These guidelines supersede all previous geotechnical guidelines and are subject to revision without notice. These Guidelines contain Soil Investigation and Enabling Works requirements and any items not covered specifically here in shall be in accordance with the latest editions of British Standards. The Consultant shall ensure that the selected design standards are the latest editions and fully compatible with Trakhees Building Regulations and Design Guidelines-Structural.

1.2

BASIC GUIDELINES FOR SOIL INVESTIGATION REPORT The purposes of site investigation is assessing its suitability for the construction of civil engineering and building works and of acquiring knowledge of the characteristics of a site that affect the design and construction of such work and the security of neighboring land and property. For new works, the objectives of ground investigations are to obtain reliable information to produce an economic and safe design, to assess any hazards (physical or chemical) associated with the ground, and to meet the construction requirements. The investigation should be designed to verify and expand inf ormation previously collected. 1.2.1

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Fig. (1.1) Boreholes Distribution propriate for structures should normally be 20 – 40 m. Where a certain project consists of a number of adjacent units, one exploration point per unit may suffice if the data of the boreholes have shown a uniform soil formation. In uniform soil conditions, the borings or excavation pits may be partially replaced by penetration tests or geophysical soundings. (B.S. 5930-1999). Fig. (1.1).5930-1999). Fig. (1.1).

Soil investigation report for any structure shall be mainly based upon its

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1.2.3

1.2.4

Normally exploration should be undertaken below all deposits that may be unsuitable for foundations purposes, e.g. made ground and weak compressible soils, including weak strata overlain by a layer of higher bearing capacity. If rock is found, a penetration of at least 3.00 m in more than one borehole may be required to establish whether bedrock or a boulder has been encountered.

1.2.5

For piled foundations, the borings, penetration tests or other in-situ tests should normally be performed to explore the ground conditions to such depth that ensures the design certainty. The exploration depth below the pile toe level normally taken as 5 times the diameter of the pile shaft or 5.00 m whichever is greater. However, there will be cases when substantially deeper soundings or borings are needed subject to the specialist advice. It is also a requirement that the investigation depth shall be at least equal to the width of the rectangle circumscribing the group of piles forming the foundation measured downward from the pile toes level.

1.2.6

1.2.7

1.2.8

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For pad and strip foundations, the depth of soundings or borings below the anticipated foundation level should normally be between 2.5 and 3 times the width of the foundation elements (minimum 8.0m depth for any borehole). Greater depths should usually be investigated in some of the exploration points to assess the settlement conditions and possible ground water problems subject to the specialist recommendation. For rafts, the depth of in-situ tests or borings should normally be equal to the foundation width.

The greater the natural variability of the ground, the greater the extent of the ground investigation required to obtain an indication of the character of the growoints to establish the overall geological structure. The lateral and vertical extent of the investigation should cover all ground that may be significantly affected by the new works or their construction. An intensive investigation can only reduce uncertainties. Boreholes coordinates (x, y) as well as the levels referred to DMD to be presented on the site layout. The site layout should reflect the essential data such as the plot limits, legend, north direction, neighbouring structures, traffic, utilities, vegetation, hazardous chemicals …etc as shown in Fig. (1.1). Suitably qualified and experienced geotechnical engineer should normally be responsible for recording the information obtained from the borehole as it arises at field; this should include a measured record of strata, with simple soil and rock descriptions. The driller in charge of an individual drilling rig should be skilled in the practice of exploration of the ground by means of boreholes, simple sampling and testing, making groundwater observations in boreholes, and properly recording the in-

SECTION: 1


formation obtained. The boring log shall highlight and describe any fluid loss (mud loss) during drilling at any depth interval, and where ever open cavities were encountered, (as sudden drop of drilling rods, etc…) description of the depth interval and field observations shall be included. Boreholes should be carefully backfilled, concreted or grouted up. Trial excavations should be outside the proposed foundation areas. 1.2.9

Geological stratum or design borehole must clarify the thickness of each soil layer with the characteristic properties.

1.2.10 At the top of Sand stratum, and thereafter at 1 m intervals of depth, a standard penetration test should be carried out as per Fig. (1.2). For Rock layers, Continuous rotary core sampling should be used as shown in Fig. (1.3). Correlation between SPT Blows & Sand Relative Density is as per Table (1.1).

Standard penetration Test (SPT) P&D ASTM D 1586

83.5-kg Drop Hammer Repeatedly Falling 0.78m

Need to Correct reference energy eficiency of 60% (ASTM D 4633)

AnvII Borehole Drill Rod (”N” or *A” Type)

g n i h t o o S s s w r o t e l B e f m o . 3 . o 0 N r = e p N

Note: Occasional Fourth Increment Used to provide additional soft material

Split-Barrel (Drive) Sampler (Thick Hollow Tube): O.D. = 50mm I.D. = 35mm L = 780mm m 5 1 Q m 5 1 Q m 5 1 Q

n s i n t e n v e i r m D e r r e c n l i p e m v a i s s s e w c o c l l u o s H 3

First Increment Second Increment Third Increment

SPT Resistance (N-value) or “ Blow Counts” is total number of blows to drive sampler last 300mm (or blows per feet).

Schematic presentation of an standarf Penetration Test

Fig. (1.2): Procedures for Standard Penetration Test (SPT)

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State of Packing

Very Loose Loose Compact Dense Very Dense

Relative Density

Standard Penetration Resistance (N)

Static Cone Resistance (qc )

Angle of Internal Friction ( )

Percent

Blows / ft

Tsf or kgf/cm 2

Degrees

< 20 20 - 40 40 - 60 60 - 80 > 80

<4 4 - 10 10 - 30 30 - 50 >50

< 20 20 - 40 40 - 120 120 - 200 > 200

< 30 30 - 35 35 - 40 40 - 45 > 45

Table (1.1): Correlation between SPT Blows & Sand Relative Density


1.2.15 Unconfined Compressive Strength (UCS) MN/m2 (Minimum of Two samples for each rock layer especially when pile foundation is used, enabling the structural designer for calculations of the socket friction and end bearing). Table (1.4) indicates Rock Fracture State, Table (1.5) indicates Rock Strength Classification & Table (1.6) indicates Sandstone / Conglomerate Properties. 1.2.16 Pressure meter/dilatometer test, Fig. (1.4), must be done if the soil stiffness values versus depths are required as and when soil stratum is modelled using advanced material model through finite element analysis of the geotechnical structure. Table (1.7) indicates Elastic Parameters for Various Soils. 1.2.17

Piezo Cone Penetration Test for reclaimed soil.

Conductor cable Logger/Recorder

Cable Head Head Reducer

Winch

Upper Geophone

LowerGeophone

Fig. (1.3): Rock Core

1.2.11

Soil identification, including Atterberg limits; sieve analysis; moisture content and sulfate content tests should be performed for each soil as per the attached soil classification system in Table (1.2).

1.2.12 c kN/m2 (cohesion of soil) and (angle of internal shearing resistance) by providing direct shear test (Minimum of Two Samples for each layer). Correlations to be as per Table (1.3).

Borehole Fluid

Filter Tube

Source Source Driver Weight Overall Length

1.2.13 Unit weight of soil ( s) kN/m3 (above and below the ground water table). Correlations to be as per Table (1.3). 1.2.14 Active, passive, and at rest earth pressure coefficients (ka, kp, and ko). Correlations to be as per Table (1.3).

Concept illustrataion of P.S logging system Fig. (1.4). Pressure meter / Dilatometer Test

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Term

RQD (%)

Very Poor

0 - 25

Poor

25 - 50

Fair

50 - 75

Good

75 -110

Excellent

90 -100

Table (1.4): Rock Fracture State

Term

* indicates term to be used as suffix with the principal soil type *** indicates that soil can be classified as SAND/GRAVEL depending on the engineering behavior of the soil Plasticity Chart for classification of Fine Soils Low priority range L

Intermediate High I

H

Very High

Extremely High

V

E

Unconfined compressive strength(MN/m)

Field definition

Very weak

Gravel size lumps can be crushed between finger and thumb.

<1.25

Weak

Gravel size lumps can be broken in half by heavy hand pressure.

1.25 to 5

Moderately weak Only thin slabs, corners or edges can be broken off with heavy hand pressure

5 to 12.5

Moderately strong When held in the hand rock can be broken by hammer blows.

12.5 to 50

Strong

When resting on a solid surface, rock can be broken by hammer blows. 50 to 100

Very strong

Rock chipped by heavy hammer blows.

100 to 200

Extremely strong

Rock rings on hammer blows. Only broken by sledgehammer.

<200

Table (1.5): Rock Strength Classification

% x e d n i y t i c i t s a l P

Parameters

Sandstone

Conglomerate

Dry Density (Mg/m 3 ) Unconfined Compressive Strength (MN/m 2 )

1.35 to 1.83

3.14 to 5.15

0.81 to 3.18

1.50 to 1.63

Table (1.6): Sandstone / Conglomerate Properties Liquid Limit, % Reference: BS:5930.1999

Soil Parameters

Loose to Medium dense (Mg/m 3 )

Bulk Density Submerged Density (Mg/m 3 ) (degrees) Internal Friction Phi Coefficients of lateral earth pressures K 0 K a K p

1.6 0.6 25 - 30 0.58 - 0.50 0.44 - 0.33 2.46 - 3.00

Medium dense to dense 1.8 0.8 30 - 35 0.50 - 0.43 0.33 - 0.27 3.00 - 3.60

Dense to very dense 1.9 0.9 35 - 40 0.43 - 0.36 0.33 - 0.22 3.00 - 4.50

Table (1.3): Soil Properties Correlations

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Modulus of Elasticity (MN/m3 )

Poisson's Ratio

Loose Sand

10.35 - 24.15

0.20 - 0.40

Medium Dense Sand

17.25 - 27.60

0.25 - 0.40

Dense Sand

34.50 - 55.20

0.30 - 0.45

Silty Sand

10.35 - 17.25

0.20 - 0.40

Sand and Gravel

60.00 - 172.50

0.15 - 0.35

Type of Soil

Table (1.2): Soil Classification System Engineered fill 2.0 1.0 > 40 0.36 0.22 4.50

Soft Clay

4.10 - 20.70

Medium Clay

20.70 - 41.40

Stiff Clay

41.40 - 96.60

0.20 - 0.50

Table (1.7): Elastic Parameters for Various Soils

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1.2.18 All equipments, materials and procedure associated with the geotechnical work should comply with the latest editions of relevant standards and codes of practice as listed:

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-

BS 5930: 1999 British Code of Practice for site investigation.

-

BS 8002-1994 British Code of Practice for Earth retaining structures

-

BS 6031-1981 British Code of Practice for Earth works

-

BS 8004-1986 British Code of Practice for Foundations

-

ASTM Volume 4.08 “Soil & Rock”, where applicable.

-

ASTM D 2938-95 for Unconfined Compressive Strength and sample comply with ASTM D 4543 – 08, Cl.3.1.

-

BS 1377-1990 Methods of tests for Soils for civil engineering purposes

-

BS1377-9:1990, 3.3 for standard penetration test.

-

BS 1377-9:1990, 4.1 for plate load test.

-

BS 1377-9:1990, 2.1 and 2.2”, Core cutter methods “BS 13779:1990, 2.4”, Water replacement method “BS 1377-9:1990, 2.3”, Rubber ballon method “ASTM D 2167-08” and Nuclear methods “BS 1377-9:1990, 2. For soils bulk densities, Sand replacement method “

SECTION: 1


-

BS 1377. Part 2: 1990 Method 8.3 for Specific Gravity (Particle Density). Method soil samples to be prepared according to BS 1377, Part 1 1990, clauses 7.3 & 7.4.4.

-

BS 1377: Part 3: 1990 (Amd. 9028/96) Cl. 5.2(Acid Extract) / (Water Extract). For Test Method: BS 1377: Part 3: 1990 (Amd./9028) Cl. 5.5 (Water Extract / Acid Extract). Sulphate Content of Soil: For Sample Preparation.

-

BS 1377: Part 3: 1990 (Amd. 9028/96) Cl. 7.2.3 (Water Extract) / 7.3.3 (Acid Extract). For Test Method: BS 1377: Part 3: 1990 (Amd. 9028/96) Cl. 7.2 (Water Extract) / 7.3 (Acid Extract). Chloride Content of Soil: For Sample Preparation.

-

BS 1377: Part 3: 1990 (Amd. 9028/96) Cl. 9.4. For Test Method: BS 1377: Part 3: 1990 (Amd. 9028/96) Cl 9.5. pH of Soil: For Sample Preparation.

-

BS 1377: Part 3: 1990 (Amd. 9028/96) Cl. 5.4. For Test Method: BS 1377: Part 3; 1990 (AMD. 9028/96) Cl. 5.5. Sulphate Content of Ground Water: For Sample Preparation.

-

BS 1377: Part 3: 1990 (AMD. 9028/96) Cl. 5.4. For Test Method: BS 1377: Part 3 1990 (Amd. 9028/96) Cl. 7 (Mohr Method). Chloride Content of Ground Water: For Sample Preparation.

-

BS 1377: Part 3: 1990. Gypsum Content.

-

BS 1377: Part 3: 1990 (Amd. 9028/96) CI.9.4. Test Method: 8S 1377: Part 3: 1990 (Amd. 9028/96) Cl. 9.5. pH of Ground Water: For Sample Preparation.

-

BS 1377:1990 Part 3 AMD 9028/96 C l.5, Cl.7 & C1.9 for Chemical Analysis of Soil and Water.

-

BS 1377:1990 Part 2 AMD 9027, Method 3 for moisture content.

-

-

BS 1377:1990 Part 1 Cl.7.3 AMD 8258/95 for Particle Size Analysis and BS 1377:1990 Part 2 Cl.9.2 AMD 9027/96 for test method.

BS 1377: Part 3: 1990, Cl.6 (Amd. 9028/96) - Determination of the Carbonate Content .

-

BS 1377 : Part 3 : 1990, Cl.3 (Amd. 9028/96) - Determination of the Organic Matter Content. Table (1.8) is for Carbonate Classification System

-

BS 1377:1990 Part 2 AMD 9027, Method 4.3 for liquid limit for clayey soils.

-

ASTM D 5731-02 - Determination of the Point Load Strength Index of Rock

-

BS 1377:1990 Part 2 AMD 9027, Method 5 for plastic limit and plasticity index for clayey soils.

-

BS 1377: Part 7: 1990, Cl.4 (Amd.8262/94) - Determination of Shear Strength by direct Shear (small shear box apparatus)

-

BS 1377:1990 Part 2 Cl. 6.5.4 for linear shrinkage.

-

-

BS 1377: 1990 Part 4 Cl. 7 for CBR tests.

ASTM D 2664-04 -Standard Test Method for Tri-axial Compressive Strength of Un-drained Rock Core Specimens without pore Pressure Measurements.

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-

ASTM D 3148-02 - Standard Test Method for Elastic modulii of intact rock core specimen in uni-axial compression.

-

Where conflicts exist, the most stringent specification should be applied. INCREASING GRAIN SIZE OF PARTICULATE DEPOSITS

0.002mm

0.06mm

2mm

60mm

Carbonate SILT

Carbonate SAND

Carbonate GRAVEL

Clayey Carbonate MUD (carbonate clay)

Siliceous Carbonate SILT

Siliceous Carbonate SAND

Siliceous Carbonate GRAVEL

Calcareous CLAY

Calc areous Sili ca SILT

Calcareous Sili ca SAND

Calcareous Sili ca GRAVEL

Carbonate MUD (carb. clay)

90

50

CLAY

Silica SILT

Silica GRAVEL

Silica SAND

CALCILUTITE(carb.mudstone) CALCISILTITE(carb.siltstone) CALCARENITE(carb.mudstone) CALCIRUDITE(carb.congl . or breccia) NI

10

R

Clayey CALCILUTITE A

Siliceous CALCILUTITE

Siliceous CALCARENITE

the subsurface explorations. 1.2.23 Presenting the ground or subsurface conditions and the geology of the site through the findings of the boreholes giving full details of the strata encountered on boreholes Logs having an accurate classification of the soils according to BS 5930:1999. The boreholes Logs must indicate the necessary figures that describing the relative density of the coarse grained-soils and the quality and the strength of rock such as: •

Standard Penetration Test (S.P.T) with cone or without. Fig. (1.2)

•

Water content (W.C.) for cohesive soils.

•

Liquid Limit (L.L.) for cohesive soils.

•

Plastic Limit (P.L.) for cohesive soils.

•

Unit weight of soil ( s) above and below the ground water table. Table (1.3).

•

Sieve analysis of soils.

•

Hydrometer analysis for soils having %fines greater than 10%.

•

Free Swell (F.S.) for swelling soils.

•

Rock Quality Designation (RQD) for rock soils. Table (1.4)

•

Total and Solid Core Recovery (TCR & SCR) for rock soils. Fig. (1.3).

•

Unconfined Compressive Strength (UCS) for rock soils. Table (1.6)

•

Point load tests on rock samples.

•

Pressure meter test. Fig (1.4)

•

And other any specialized tests that may be specified in the project specification including:

90

C E


T O

Siliceous CALCIRUDITE T O

S

A

50 IN

L

G C L

Calcareous CLAYSTONE TI H IF IC

Calcareous SILTSTONE

CLAYSTONE A T

CalcareousSANDSTONE

SILTSTONE

SANDSTONE

Fine grained LIMESTONE IO

CalcareousCONGOLOMERATE CONGLOMERATE or BRECCIA

R B O

10 N A T E

Detrital LIMESTONE

90

N

Fine grained Argilaceous LIMESTONE

A

C O N

Fine grained Siliceous LIMESTONE

Siliceous Detrital LIMESTONE

T

ConglomeraticLIMESTONE E N T

50 Calcareous CLAYSTONE

Calcareous SILTSTONE

CalcareousSANDSTONE

CalcareousCONGOLOMERATE

SILTSTONE

SANDSTONE

CONGLOMERATE or BRECCIA

CLAYSTONE

10

CRYSTALLINE LIME STONE or MARBLE

50 Conventional metamorphic nomenclature applies in this section

e t d e v a e i h n s i m s t i x t n e r n e o r r o t c p p n S m p o U A C

Very soft to hard (<36 to 300kn/m2)

f n o o i t e a e r r g u e d n D i

Non-indurated

Hard to moderately weak (0.3 to 12.5 MN/mn2)

Slightly indurated

moderately strong to strong (12.5 to 100MN/m2)

strong to extremenly strong (70 to > 240MN/m2)

Moderately indurated

Highly indurated

-

Instrumented UCS tests to measure the small local modulus and Poisson’s ratio. Table (1.7).

-

UU and CD tri-axial compression tests on soil and weak rock, including instrumented tests for local modulus determination. Table (1.7).

-

Consolidation tests on cohesive soils.

-

Collapse potential tests on upper sand within the upper zone of un-saturation.

Table (1.8): Carbonate Classification System 1.2.19 Performing engineering analysis of field and laboratory findings. 1.2.20 The visual description of the geotechnical engineer at site for soil samples and procedures used for sampling, transportation and storage. 1.2.21 Method of sampling the undisturbed, Split Spoon (for SPT) for disturbed samples. Fig. (1.2). 1.2.22 Tabulation of quantities of field and laboratory work, presentation of field observations which were made by the supervising field personnel during

22

23

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-


Borehole Log must confirm scale, sample key, legend for type of soil, ends of stratum and ground water table level.

1.2.24 Stating the depths range at which the ground water table was encountered and to show if the ground water table is subjected to tidal weather seasonal variations or by artificial induced effects. Therefore reconfirmation is recommended prior to any works related to the ground water regime. Standpipe peizometers to be installed inside minimum two boreholes for each site after drilling and cleaning of drilling mud by clean water flushing for monitoring the ground water depth. 1.2.25 Conducting a number of field permeability tests (Falling head for soil and packer tests for consolidated and rock material) to measure the conductivity of ground materials. 1.2.26 Earth profile must be plotted using the findings of boreholes in different ground sections as per Fig. (1.5).

) 2 m c / g k (

600

Sample No: NU1

4

500 A t s p , n o t s i p n o s s e r t S

= 8.5

400

2

B

c = 1.10

300

0

200

) 2 m c / g k (

100 0

1 2

4

6

8

10

(kg/cm2)

Sample No: NU2

4 0

0.1

0.2 0

0.3 0.1

0.4 0.2

PENETRATION, INCHES

0.5

2 c = 1.90

= 5.5

0 1 2

4

6

8

10

(kg/cm2)

Fig. (1.6): Describing Soil Properties

1.2.27 Mentioning all the field and laboratory tests achieved in details and illustrating the results properly as per Fig. (1.6). 1.2.28 Chemical analysis to study the possible susceptibility of foundation concrete to aggressive in-situ conditions and corrosivity and thereby to determine the concrete mix specifications by determining pH, Sulphur Trioxide and Chloride content of the soils and ground water. Minimum number to be considered should be three soil samples from above the ground water table, and three ground water samples for each plot. 1.2.29 Recommendations for choice and the type of foundation based on the geotechnical study carried out by the geotechnical engineer and the local experience in the area. 1.2.30 Information about the seismicity of the area; Soil Profile Type to be considered in the seismic analysis according to (Table 16-J) as per UBC 1997, Volume 2, ‘Structural Engineering Design Provisions’, Division IV ‘Earthquake Design’. Conduct a representative downhole / cross hole seismic logging test(s), Fig. (1.7), for an appropriate number of boreholes based on the area of the site and geologic variations, to measure the shear and primary seismic wave profiles and dynamic soil / rock parameters. Table (1.9) is for UBC 1997 Soil Profile Class Estimation.

Fig. (1.5). Earth Profile Compacation Curve ) m / N k (

30

, t h g i e W t i n U y r D

150

ZAV = zero air void curve (G 8 = 2.70)

3

25 20

Maz. Dry Unit Weight

15 10

Optimum Moisture opt Content, w

5 0 0

5

S= 100% 80% 70% Measured at varying moisture contents

10 15 20 Water Content, w (%)

25

peak =43.4 Nonlinear

) 100 a P k ( s s e r t s 50 r a e h S

=44.6 =9.8

0

0 50 100 Normal stress (k Pa) b) Shear strenghts envelopes

cv =36.2

150

200

1.2.31 Liquefaction analysis in case of reclaimed soil: (CPTU is highly recommended).

1 mm = 0.03in 1 kPa = 0.145 lbf/in 2

Fig. (1.6): Describing Soil Properties

24

25

SECTION: 1

SECTION: 1



1.2.32 Calculation of cyclic stress ratio (CSR, earthquake “Load”) induced in the soil by earthquake. The ground motion parameters are: UBC zone class: 2A, Richter Magnitude M=6.0 & maximum ground acceleration a=0.225g at ground level or 0.15g at cap rock level (Amplification Factor = 1.5) unless otherwise specified by the main developer.

Well

Ground Surfaces

Lower Reciver

1.2.33 Calculation of cyclic resistance ratio (CRR, soil “strength”) based on in-situ test data from SPT (Seed & Idriss) or CPT method (1996 NCEER workshop on Liquefaction Evaluation).

e a v W c t e ir D

1.2.34 Evaluation of liquefaction potential by calculating the factor of safety against liquefaction from the earthquake load and soil strength. 1.2.35 [F.S. = CRR/ (1.2-1.5) CSR]. There are a potential for liquefaction if the F.S. less than unity, the layer is susceptible to liquefy and the ground densification or mitigation measures are needed.

2m Downhole Hydrone Upper Reciver

1.2.36 Estimation of liquefaction induced settlement. Fig. (1.7). Standard Down Hole Seismic Soil/Rock Description

Shear Wave Velocity (m/s) 1500 760 to 1500

SPT Range

Hard Rock Rock Very Dense > 50 360 to 760 Soil & Soft Rock Stiff Soil Profile 180 to 360 15 to 50 Soft Soil Profile 180 <15 Soil Requiring Site - Specific Evaluation

UCT Range (Kpa)

Soil Profile Type

-

SA

100

SC

50 to 100 50

SD

1.3

RECOMMENDATIONS TO BE INCLUDED IN THE SOIL INVESTIGATION REPORT: EXCAVATION WORKS: Excavation works should be carried out in

1.3.1

accordance with good construction practice and following BS 6031:2009 “Code of Practice for Earthworks”. Recommendations for excavation of rock for cases of deep excavations should be provided. Fig. (1.8).

SB

SE SF

SPT: Standard Penetration Test on Soil UCT: Unconfined Compressive Strength Test on Rock Hence, the following coefficent can be adopeted: For very dense SAND and soft rock, the soil Profile Type is Sc In addition, the following other parameters can be considered:

The Seismic Coefficients C vand C acan be considered with depending on the Seismic Zone Factor (Z): Swismic Zone Factor Z=0.15 Soil Profile Type SA SC SE SB SD 0.12 0.15 0.18 0.22 0.30 Swismic Coefficient Ca Swismic Coefficient 0.12 0.15 0.25 0.32 0.50 Cv Hence, the following coefficients can be adopted also: For Soil Profile Type SD, The Seismic Coefficient C a is 0.22 For Soil Profile Type SD, The Seismic Coefficient C is 0.32

22

21 50

7

8

9

10 11 52

31

q=100kps

23 30

33 20 90 19 18 Roack ArmourCole Maloe 1718 35 36 38 34 16 57 54 53 40 5040 50 55 52 27 14 15 12 13 5050 51 25 18 44 48 26 484748 72 55 74 66 70 64 64

50

4 87

81

82

40

3 37

60

7

Bedrock

70

80

90

100

110

Fig. (1.8): Safe angle for open excavation 1.3.2

OPEN EXCAVATION AND PROTECTION: Where space permits and above the water table, sides of the excavation would be necessary to be battered. The CIRIA Report No. 97 “Trenching Practice” recommends a maximum safe temporary slope of 35 degrees to the horizontal. Recommendations for the safe angle for open excavation in different related soil

Table (1.9): UBC 1997 Soil Profile Class Estimation

26

27

SECTION: 1

SECTION: 1


and / or rock materials are to be provided, in accordance to related technical guidelines and local requirements. 1.3.3

BACKFILL MATERIALS AND COMPACTION CRITERIA: The material used for backfilling purpose (Maximum 2.00 m thickness) shall be of selected fill composed of sand/granular mixture free from organic materials or other deteriorates substances. The Plasticity Index of the backfill material shall not exceed 10%. The maximum particle size of backfill material shall not exceed 75m and the percentage passing 75m Sieve shall not exceed 20%. The organic materials content should not exceed 2% and the water soluble salt content shall not exceed 5%. The backfill materials shall be placed in layers of thickness 150mm to 250 mm and to be compacted to not less than 95% of the maximum dry density. The specialist must state whether the material available in site could be used for general backfilling or not after performing the necessary analysis. Sand cone test may be carried out to determine the degree of compaction while the plate load test (as per ASTM D1195/D1195M–09) also is an acceptable test where the bearing capacity corresponds to the allowable settlement will be confirmed.

1.3.4

RETAINING STRUCTURES: The specialist must recommend the most preferable shoring system, Fig. (1.9), (if required) as well as the soil parameters to be adopted for the design as per Table (1.3).

Step Walls

Water above Ground

Concrete Seal


1.3.5

DEWATERING: Care should be taken during dewatering to ensure that fines are not removed during pumping since this could result in unpredicted settlements of the surrounding ground and associated structures. -

Fig. (1.10) Indicates Surface Dewatering System (French Drains).

-

Fig. (1.11) Indicates Well Point Dewatering System

-

Fig. (1.12) Indicates Deep Wells Dewatering System.

-

Fig. (1.13) Shows the Well Pit Details during running dewatering and after dewatering

-

Fig. (1.14) Indicates the Details of Dewatering Deep Well

50-100 cm

3/8 Aggregate fill m o 0 0 10 8

100-150 mmPVC Slotted Pipe Geo Textile Wrap

Final Excavation Level

Complicated Ground

Typical Section of French Drain System Brace above Ground

Deadman and Raker

Fixed Length

ah

LimitedEmbedment due to bedrock

av

Surcharge and Earthquake

Different Lagging Spacing

Helix and Tieback Anchor

External Force on Wall

Fig. (1.10): Surface Dewatering System (French Drains)

E-80 Cooper Railroad

Fig. (1.9): Shoring Systems

28

29

SECTION: 1

SECTION: 1



Installation level

FLEXIBLE PIPE

Diaphragm wall shoring

Deep well

Anmored cable Discharge Hose

GROUND LEVEL

Deep well Submersipie Pump

First Stage PVC WELL POINT PLASTIC PIPE

Fig. (1.12): Deep Wells Dewatering System

AGGREGRATE AROUND WELL POINT PIPE

F O R E T IL F

O P L L E W

E PI P T NI

Discharge to approved point R E T E M 1

Discharge buried 30 cm below excavation level (if required). Trench Final excavation level

Well pit

CONNECTION OF PVC WELL POINT PIPE TO THE STEEL HEADER PIPE

Anmored cable

Fig. (1.11): Well Point Dewatering System

Discharge hose Diaphram Wall Deep well Submersibia pump

Inner face

Well Discharge

Final Stage

Fig. (1.12): Deep Wells Dewatering System

30

31

SECTION: 1

SECTION: 1



To Main Line Water Prooling membrane

RAFT

DEWATERING WELL

Installation level

RAFT

Well caslng( 400-450mm Dla)

1600mm

Bored hole(800-1000mm) Discharge from pump

R.c.c pipe entry form deep well open

Platform

Flowmeter Internal tube for measurement fi 40 PVC

Smooth Steel Tube

External tube for measurement fi 40 PVC

e b u T h t o o

Tube of

600mm

Filing block work 400mm

Repression m S

h t p e D

Calibrate Filtration Gravel

Filter material(3/8 Aggregate)

P.C.C Internal tube for measurement fi 40 PVC

100mm 200mm 80mm

Perforated Steel Tube

TYPICALWELL PIT

Submersible pump

(Dewatering runing,well pit open) 800-800mm

TYPICAL CROSS SECTION OF

Fig. (1.13): Well Pit Details (Running / Finished)

External tube for measurement fi 40 PVC

E B U TExcavation D E M W.T. R O F R E P

Excavation W.T. External Tube Well Toe & Tube

DEEP WELL

Stopper

Fig. (1.14): Details of Dewatering Deep Well

Raft

TO MAIN LINE

Water Proofing

Raft

Installation level Initial Water Table level

1600mm

Genaral P.c.c

R.c.c Deep Well Closed 600mm Fitting

H

Block Work

Final excavation level Final Water Table Level after drawdown

P.c.c 100MM 80MM 200MM WELL PIT DETAILS (Dewatering finished,wellpit closed)(Building Contractor)

Fig. (1.13): Well Pit Details (Closed)

32

Drawdown curve

h

Level of water retalned in the well

hw

Fig. (1.14): Details of Dewatering Deep Well

33

SECTION: 1


1.3.6

-

The foundation level should be in compliance with the architectural requirements.

1 PILE

Net allowable bearing pressure to be determined considering shallow foundations at the foundation level using practical experience and the results obtained from the field standard penetrations tests, the empirical equations developed by TerzhagiPeck/Merehof and modified by Bowles considering a proper FOS against shear failure of the soil.

2 PILE

7 PILE

-

Using the calculated allowable bearing pressure value, the total settlement for isolated/strip footing and raft foundation shall be within 25mm & 50mm respectively. The differential settlements should be indicated.

11 PILE

-

The proposed foundation recommendations must ensure that an adequate safety factor against likely uplift pressure established based on selected Design GW level is satisfactory to local authority and / or project requirements particularly when basement floor(s) exist.

14 PILE

-

Modulus of sub-grade reaction ks (kN/m3) shall be indicated in the soil report when the raft foundation is recommended.

-

The foundation ground must be proof rolled with vibratory compactor to confirm that any loose materials are compacted to not less than 95% of the maximum dry density obtained by performing modified Procktor test.

-

-

The geotechnical report shall include an estimate of single pile

4 PILE

8 PILE

5 PILE

9 PILE

12 PILE

15 PILE

6 PILE

10 PILE

13 PILE

16 PILE

vertical and lateral stiffness for the adopted pile cut off levels and penetration depths. Lateral stiffness shall be based on cyclic conditions. The assessment of pile group effects on vertical and lateral stiffness shall be performed by the foundation design Engineer.

The specialist should confirm in writing that the undesirable materials have been removed, the foundation ground has been inspected and the recommended bearing capacity corresponding to the foundation depth is properly achieved.

The soil report should propose the suitable type of pile to be used, the allowable working loads in compression and tension considering minimum factor of safety of 2.5. Piles spacing should be recommended in the piling recommendations Minimum 2.5 the pile diameter, Fig. (1.15). It should be noted that the minimum pile toe level should be at least at depth of two times the diameter of pile socketed in the hard strata in order to consider this strata in the design.

3 PILE

Fig. (1.15): Piles Distribution

-

For bored cast-in-situ piles, settlements of the order of 1% of the pile diameter is normally required to mobilize full skin friction whereas full bearing is developed at much higher settlements (usually at 10% of pile diameter). Therefore, it is recommended that the pile capacity shall be based on full skin friction and partial end bearing.

-

Where the borehole depth is not satisfactory for the design, additional boreholes should be carried out to the required depth to reconfirm the continuity of the strata.

PILE FOUNDATIONS -

34


SHALLOW FOUNDATIONS -

1.3.7

SECTION: 1

1.3.8

FOUNDATION CONCRETE Concrete mix design should consider strictly the chemical analysis data for both soil and water and to be in line with Trakhees Construction Materials Quality Control Guidelines.

1.3.9

LIQUIFACTION: The likely liquefaction induced effects are: -

Settlement.

35

SECTION: 1


1.4

-

Surface manifestation.

-

Lateral spreading or land sliding.

-

Loss of bearing capacity for shallow foundation.

-

Loss of lateral soil stiffness

SECTION: 1


SOIL IMPROVEMENT GUIDELINES POUNDER

1.4.1

Soil liquefaction improvement techniques may be characterized as densification, drainage, reinforcement, mixing, replacement, Vibro Compaction, Vibro replacement (Vibro Stone Columns), deep dynamic compaction and compaction jet grouting. •

•

PATH #

2

1

1

2

1

WORK PLATFORM

Wick drains, Fig. (1.16), are also an accepted technique whenever a permanent dewatering is provided. However, the use of this technique should be evaluated with extreme caution. Fig. (1.17) Shows the method statement of the dynamic compaction and in Fig. (1.18) Comparison between dynamic and vibro compaction is presented with respect to tip resistance along depth.

2

LOOSE SOIL

COMPACTED SOIL

FIRM BASE

Fig. (1.17): Method Statement of Dynamic Compaction

DYNAMIC COMPAC TION

VIBRO COMPACTION

HYWARD BAKER

0 0 2 4 6 8 10 12 14 16 18 20

5

10

15

20

25 30

0 2 4 6

0

5

10

15

20

25

30

8 10 12 14 16 18 20

Fig. (1.18): Comparison between Dynamic & Vibro Compaction

Fig. (1.16): Wick Drains Technique

36

37

SECTION: 1

SECTION: 1


•

•

Range of soil (particle size-sieve analysis) suitable for vibratory techniques are zoned in Fig. (1.19) Indicating the best improvement technique suitable for such soil. Fig. (1.20) Shows the most suitable techniques for both cohesive and granular soils. The prices per cubic meters of the treated soil with respect to depth for surface compaction, dynamic compaction and deep vibro compaction are presented in Fig. (1.21) to ease the decision for the proposed improvement technique with respect to cost for granular soils Range of soils suitable for vibratory techniques


Stone Columns + Preload

+80-100 in

+25-36 in

COHESIVE SOILS: Clays, Sites, Peats Vibroflocation

100%

Controlled Modulus Coloumns

Dynaminc Replacement

DynamicCompression

90% 80% 70%

Compressive Soil

60% 50% D

40%

C

B

A

GRANULAR SOILS: Gravel, Sand, Fill

30%

Fig. (1.20): The Most Suitable Improvement Techniques for both Cohesive and Granular soils

20% 10% 0% 0.001

0.01

0.1

1

10

100

1000

Particle size (mm)

Zone A: The soils of this zone are very well compactable. The right borderline indicates an empirically found limit where the amount of cobbles and boulders prevents compaction because the vibroprobe cannot reach the compaction depth. Zone B: The soils in this zone are suited for Vibro Compaction. They have a fines content of less than 10%. Zone C: Compaction is only possible by adding suitable backfill (Material from zones A or B) from the surface (stone columns or sand columns). Zone D: Stone columns are a solution for a foundation in these soils. There is a resulting increase in bearing capacity and reduction on total and differential Fig. (1.19): Range of Soils Suitable for Vibratory Techniques

38

0

Price per m3 treated soil

2

4

HEIC (Impact Roller)

6

DC (WeightDropping)

8

Vibro Compaction (DepthVibrator)

10

Treatment Depth [m]

Fig. (1.21): Cost Comparison for the Different Improvement Techniques for Granular Soils

39

SECTION: 1

SECTION: 1



1.4.1.a Deep Compaction (Vibro Compaction) The Vibro Compaction technique, Fig. (1.22), is most suitable for medium to coarse grained Sand with less than 10 % material finer than 63 m and clay content (particle size less than 0.002 mm) of less than 2%. Cohesive soils consisting of silt and clay material do not respond to vibratory compaction. The range of soils suitable for a vi bratory technique is shown on, Fig. (1.19).

Follow up tube Coupling

Electric Motor Bearing Eccentric Nose Cone

Fig. (1.23): Deep Compaction (Vibro Compaction) Method Statement

48 mm amplitude

Penetration

Compaction

Backfilling

Fig. (1.22): Deep Compaction (Vibro Compaction) Technique

•

The Vibro Compaction can increase the in situ density. Increase in soil density is achieved through compaction by an applied static or dynamic stress. The advantage of Vibro compaction is to mitigate liquefaction for depths up to 20.00m.

•

The compaction pattern shall be proposed on a triangular pattern with maximum grid dimensions of (3.00 – 5.00) m or as recommended by the specialist. Smaller spacing may be tried in case of not reaching the specific test result. The re-compaction may be required in case of where compaction criteria have not achieved. Fig. (1.23) shows the vibrocompaction method statement.

1.4.1.b Dynamic Compaction

Dynamic compaction, Fig. (1.24), involves lifting and dropping a heavy weight several times in one place. The process is repeated on a grid pattern across the site. Trials indicate that the masses in the range 5 to 10 tones and drops in the range 5 to 10m are effective for compacting loose sand.

h m

Fig. (1.24): Dynamic Compaction Technique

40

41

SECTION: 1


SECTION: 1


1.4.1.c Soil Replacement

Vibro-Replacement Stone Columns: Vibro-replacement stone columns, Fig. (1.25), improve the resistance of cohesionless soils to liquefaction by several mechanisms. The primary mechanism of treatment is the densification of the native soil. Secondary benefits may also come from the reinforcing effects of the stone columns (e.g.,. they are usually stiffer than the surrounding soil), an increase in the in-situ horizontal stress (e.g., due to the packing of stone in the column), and the drainage of earthquakeinduced pore water pressures through the stone columns. Vibro-displacement method uses compressed air to displace the soil laterally as a probe is advanced through the weak strata. Backfill is placed in to the hole in stages as the probe is incrementally withdrawn and lowered again to compact the fill. This process, also known as the ‘dry method’, forms a stone column. The columns are typically smaller in diameter than the ‘wet’ method and are used in the stiffer soils.

Fig. (1.26): Deep Mixing (Soil Mixing) Technique Typically, the reagent is delivered in a slurry form (i.e. combined with water), although dry delivery is also possible. Depending on the soil to be mixed, the volume of slurry necessary ranges from 20 to 30 percent by volume. Can be a variety of materials including: Cement (Type I through V), Fly ash, Ground Blast Furnace Slag, Lime, Additives.

Fig. (1.25): Vibro-replacement Stone Columns Technique 1.4.1.d Soil Mixing

Soil Mixing, also known as the Deep Mixing Method, Fig.(1.26), is the mechanical blending of the in situ soil with cementitious materials (reagent binder) using a hollow stem auger and paddle arrangement. The intent of the soil mixing program is to achieve improved character, generally a design compressive strength or shear strength and/or permeability. Soil mixing can also be used to immobilize and/or fixate contaminants as well as a treatment system for chemical reduction to a more ‘friendly’ substrate

42

No single tool will be the best for all soil types and, for this reason, mix tools are often developed for individual projects. Considerations include: soil type and available turning equipment, often designed for particular site conditions, size ranges from 1.6 to 11.5-ft diameter, can be a combination of partial flighting, mix blades, injection ports and nozzles, and shear blades. The in situ injection and mixing of cement into weak soils is becoming more common. Recent applications include liquefaction mitigation and the strengthening of weak cohesive soils adjacent to embankments, levees and bridge abutments. 1.4.1.e Grouting

Grouting can stiffen and strengthen the soil layer by increasing its density, increasing the lateral stresses, and acting as reinforcement. Grouting may also be used to produce controlled heaving of the ground surface to re-level a structure that has been damaged by differential settlements.

43

SECTION: 1

SECTION: 1


There are different procedures or methods of grouting, Fig. (1.27), that can be classified as; permeation (cement or chemical injection) grouting, compaction grouting, jet grouting.


Cement Grouting, Fig. (1.29), also known as Slurry Grouting, is the intrusion under pressure of flowable particulate grouts into open cracks and voids and expanded fractures. Slurry Grout Materials may be Cement, Clay (Bentonite), Sand, Additives, Microfine Cement, Fly Ash, Lime and Water

Fig. (1.27): Different procedures of Grouting Techniques 1.4.1.f Permeation Grouting

Structural chemical grouting is the permeation of sands with fluid grouts to produce sandstone like masses to carry loads. Water control chemical grouting is the permeation of sands with fluid grouts to completely fill void to control water flow. Permeation grouting, Fig. (1.28) can be used for lagging operation, support of footing, grouted tunnel support, grouted cut-off wall and grouted pipeline support.

Fo r La gg in g O per at io n

S up po rt of Fo ot in g

G ro ut ed Tu nn el S upp or t

Pit Excavation Below Water

Grouted Cut-Off Wall

Grouted Pipeline Support

Fig. (1.29): Cement Grouting (Slurry Grouting) Technique 1.4.1.g Compaction Grouting

Compaction Grouting is the injection under relatively high pressure of a very stiff, “zero slump” mortar grout to displace and compact soils in place. The monitored injection of very stiff grout into a loose sandy soil results in the controlled growth of a grout bulb mass that displaces the surrounding soils as per Fig. (1.30). This action increases lateral earth pressures and compacts the soil, thereby increasing its resistance to liquefaction.

Fig. (1.30): Compaction Grouting Technique

Fig. (1.28): Permeation Grouting Technique

44

45

SECTION: 1


SECTION: 1


The parameters to be used will be designed and checked with trial columns prior to start of the works. With jet grouting, it is possible to treat a broad range of grounds, consisting of different type clays, loose sands and to overcome the drawbacks of the other injection systems. It is a valid alternative to other consolidation systems such as dewatering, micro-piles, stone columns etc.

1.4.1.h Jet-Grout

Jet-grout is the form of jet-grout column “soil-crete pile” by drilling a hole specified with its length in the relevant design and then by jetting with proper mixing and pumping equipment with the jetting parameters to achieve designed diameter. Using a drilling rig holes between 400 to 700 mm diameters will be drilled down to required column depth. The drilling can be carried out by traditional rotary or rotary percussive methods. And then jetting will be done while dragging the drill set at a specified drag and revolution speed. The rig must be equipped with automatically adjustable drag and revolution speed controls. The jetting takes place at the bottom of the drilling set at the special tool named “monitor” with one or two nozzles the diameter of which is from 1.5 mm to 3.0 mm depending on the design parameters. The cement-water mix ejects from these nozzles at minimum pressure of 300 bars with 250 m/s jet speed. Dragging the drilling set upwards with a pre-set dragging rate while jetting is continued causes to destroy the natural structure of the soil and then mix the soil with cement-water mix at very high pressure therefore forms a jet-grout column as per Fig. (1.31).

1.4.2

SAFETY AGAINST LIQUEFACTION The hydraulic fill, loose, fine and saturated sands may undergo liquefaction (experience significant loss of strength due to build up of pore water pressure and subsequent deformation in some locations under the cyclic loading of earthquakes). The efficiency of the improvement done to mitigate the liquefaction could be ensured from CPT readings (as per ASTM D 5778 or BS 1377: Part 9: Test 3.1 Amd 8264-95 and also SSMFE test Procedure for Cone Penetration Test (IRTP), 1989 and updated 1997.) through pre and post-agreed tests. The pre CPT shall be carried out every 900 m 2 maximum, or as per project specs, to compare the results with the post compaction CPT results for the same area as per Fig. (1.31). The locations of post CPTs shall be selected at the central points and/or at one third the maximum distance between the improved points. Proper weighted average for near and far tested points should be considered. For deep foundations, the achievement of 8.0 MPa weighted average of the tip resistance profile for the post compaction CPT is an accepted criterion of the compaction efficiency. For shallow foundations, one plate load test/structure to be carried out (as per ASTM D1195/D1195M–09). The acceptance criteria shall be the achieving of targeted bearing pressure of 150 kPa corresponds to settlement of 25 mm maximum.

Fig. (1.31): Jet Grouting Technique

46

47

SECTION: 1


SECTION: 1


the FOS is less than unity, the layer is susceptible to liquefy and the ground densification or mitigation measures are needed. The accepted factor of safety shall be more than unity. The GWT level selected for the liquefaction analysis shall represent selected design value by the consultant. For CPT-Based liquefaction analysis, soil profiling according to Robertson 1996, or similar method shall be performed to highlight localities of high fines content. Wherever liquefaction analysis is carried out with specialist commercial software, a copy of the valid licence and updated manual shall be submitted to ensure that the used methodology complies with the specifications. Wherever a spread sheet was used, a copy of the spread sheet shall be submitted with verification of its accuracy (e.g solution of published problems, etc…). Level survey to be submitted before and after improvement.

1.4.4

EVALUATION OF LIKELY LIQUEFACTION INDUCED HAZARDS “Special Publication 117, GUIDELINES FOR EVALUATING AND MITIGATING SEISMIC HAZARDS IN CALIFORNIA”, adopted on March 1997 by the State Mining and Geology Board.

Fig. (1.32): Cone Penetration Test Readings

1.4.3

CALCULATION THEORY: (Recommended Procedures for Implantation of DMG Special Publication – 117 Guidelines for Analyzing and Mitigating Liquefaction Hazards in Calif ornia. Implementation Committee, March 1999- “Preliminary screening of Liquefaction” Calculation of cyclic stress ratio (CSR, earthquake “Load”) induced in the soil by earthquake. The ground motion parameters are: UBC zone class: 2A, (Richter Magnitude), M=6.0 & maximum ground acceleration a=0.225g at ground level or 0.15g at cap rock level (Amplification Factor = 1.5). Calculation of cyclic resistance ratio (CRR, soil “strength”) based on in-situ test data from SPT (Seed & Idriss) or CPT method (1996 NCEER workshop on Liquefaction Evaluation). Evaluation of liquefaction potential by calculating a factor of safety against liquefaction from the earthquake load and soil strength. (F.S. = CRR / [(1.2-1.5) CSR). There is a potential f or liquefaction if

48

The evaluation of likely liquefaction hazard shall be carried out by competent and qualified geotechnical Engineer. The evaluation shall be based on the results of adequate number of filed tests (preferably CPTU). Wherever, the analysis indicates significant liquefiable zones, and then the site or part of it shall be recommended for further deep compaction. Wherever, minor, localized liquefiable zones within li mited depth were indicated, and then it is important to assess the likely induced effects such as: a) Liquefaction induced settlement of surface foun dations, b) Surface Manifestation, c) Loss of bearing strength of surface foundations, d) Loss of lateral stiffness of piles, e) Effects on life lines, f)

Any other influences…

49

SECTION: 1


SECTION: 1


1.4.5

1.4.4.a Settlement:

To mitigate the liquefaction hazards, the treatment of the fill material shall be extended laterally by two-thirds the liquefiable layer thickness beyond the whole building foundation limits, (Lai 1988).

If shallow footings exist and no improvement has done, differential settlement more than the maximum li quefaction induced settlement should be expected and considered. 1.4.4.b Surface manifestation:

Surface manifestation such as sand boils or ground fissure may be occurred during earthquake shaking emphasising that ground settlement have already takes place noting that the settlement may be occurred even with the absence of surface manifestation. The evaluation of the potential for ground cracking and sand boils (Ishihara, 1985) is based on the thickness of the potentially liquefiable layer and the thickness of the non-liquefiable crust.

LATERAL EXTEND OF GROUND IMPROVEMENT

1.5

SHORING GUIDELINES a)

For neighbouring shallow foundation or for excavations deeper than 1.50 m, suitable side protection have to be ensured so that the excavation shall not pause a threat to the personnel working on site or cause any damage to nearby existing buildings or roads. Fig. (1.33) shows the method statement for contiguous, secant and soldier piles shoring systems.

1.4.4.c Loss of bearing capacity for shallow foundation:

As per the Implementation Committee, the loss of bearing capacity may be significantly occurred if the induced vertical stresses on liquefiable layer located at certain depth exceeds 10% of the bearing pressure imposed by the foundation. There is no recognized analytical method to evaluate the loss of bearing capacity at this time. The Committee recommends that Ishihara’s method of surface manifestation analysis to be used for shallow foundations. 1.4.4.d Loss of lateral soil stiffness:

Fig. (1.33-a). Contiguous Piles Shoring System

Loss of lateral soil stiffness has a greater impact on the design of piling and shoring works. The negative skin friction for the untreated fill layer shall be considered in determination of the pile capacity. The pile shall be considered unconstrained along the untreated layer in both vertical and lateral analysis. Lateral load to be considered due to ground motion from an earthquake of a=0.225g at ground level or 0.15g at cap r ock level. 1.4.4.e Lateral spreading or land sliding:

Such spreads can occur on gently sloping ground or where nearby drainage or stream channel can lead to static shear biases on essentially horizontal ground (Youd, 1995).

50

Fig. (1.33-b): Secant Piles Shoring System

51

SECTION: 1

SECTION: 1


Fig. (1.33-c) Soldier Piles Shoring System Method Statement for Different types of Shoring Systems

b)

Structural bending moments, shear forces and prop or tie forces should be derived from the equilibrium calculations using design earth pressures and water pressures. The ultimate limit state and serviceability limit state should be the same as those used for the overall equilibrium and deformation calculations. All Stages of constructions to be studied as per Fig. (1.34).

NITALE PHASE

PHASE 1

PHASE 2


c)

The shoring works should be designed as a rigid vertical system subjected to the earth, water pressures and support reactions taking into account the staged construction.

d)

The maximum retained height is 15.00 m (BS 8002: 1994, Section 1.1). Advice from the shoring works specialist is required in case of excavation depth of 15.00 m is required.

e)

The excavation and support systems should be designed to ensure that the settlement or lateral yield of the surrounding ground surface is within acceptable limits particularly where the excavation adjoins roads where drainage, electricity services are located. The maximum lateral displacement permitted for the shoring systems is 40 mm.

f)

The minimum surcharge load is 15 kN/m2 and value of 15 kN/m2 should be added for each neighbouring existing plot floor when the neighbouring foundation is a raft. Traffic surcharge load to be considered 20 kN/m2 at roads sides.

g)

Cantilever shoring systems are suitable for moderate height only. The maximum height of such sheet pile cantilever walls is 5.00 m. (BS 8002: 1994, Section 4.4.2.).

h)

Minimum factor of safety of fixation and embedded depth should be taken as 2.00.

i)

Bored piles contiguous or secant piles are very preferable when the shoring works is closed to an existing foundation. Difference of water levels in front and back to shoring system should be taken into consideration in case of secant piles, sheet pile wall or diaphragm wall after dewatering.

j)

Maximum spacing between soldier piles is 2.50 m and maximum spacing between tie back anchors is 4.00 m.

k)

The design earth pressure are derived from design soil strengths using the usual methods of elasto-plastic behaviour, with earth pressure coefficients given in BS 8002 : 1994, Section 1.3.9.

l)

In checking the stable equilibrium and soil deformation, retaining walls should be designed assuming a depth of unplanned excavation in front of the wall not less than 10 % of the total height retained for cantilever walls or of the height retained below the lowest support level for propped or anchored walls. The minimum unplanned depth is 0.50 m ((BS 8002: 1994, Section 3.2.2.2).

PHASE 3

Fig. (1.34): Shoring Stages of Construction

52

53

SECTION: 1

SECTION: 1


m)

n)

o)

p)

The long term analysis is likely to be critical where the soil mass undergoes a net reduction in load as a result of excavation, such as adjacent to a cantilever wall. For granular soils, the relative strength is always the drained strength and the earth pressure is always in terms of effective stresses. (BS 8002: 1994, Section 3.2.3) Concrete and reinforcement should conform to the requirements of BS 8004, BS 8110-1 or BS 5400-4, BS 5400-7 and BS 5400-8. The mix should be designed to provide the necessary structural strength and the flow requirements to ensure adequate compaction and continuity. Special methods of placement, for example by tremie tube should be taken into account. (Silwinski Z. and Fleming W.G.K, 1974.) Where props or anchors are used, wailing beams should be provided along the face of the wall at this lateral support level to unify shoring behaviour. The wailing beam may be designed as horizontally spanned steel beams. The gaps occurred in between the individual piles and the wailing beams due to irregularities or deviations from true verticality and position of individual piles should be wedged or in filled. Wherever ground anchorages are used (Fig. (1.35)), in-situ acceptance tests shall be carried out prior to anchor stressing and locking, Fig. (1.36), in accordance to BS 8081: 1989. A qualified 3rd party consultant / laboratory shall witness the tests and issue an independent report of the tests results and conclusions.


63mm HDPE ANCHOR HOLE GROUT 0.6”ANCHOR STRAND 2. GROUT HOSE 1. GROUT HOSE

AA - Cross Section (unscaled)

ANCHOR HOLE

1. GROUT HOSE 2. GROUT HOSE

GROUT

0.6”ANCHOR STRAND

ANCHOR SEPARATOR

BB - Cross Section (unscaled)

Fig. (1.35): Tie Back Anchors Method Statement G E S , W E D EA D T E, H LA P R H O A N C ANCHOR CENTRALIZER

2nd grout hose

A

ANCHOR HOLE ANCHOR CENTRALIZER 1st grout hose ANCHOR SEPARATOR

A

B

GROUT

SEAL

B

0.6 INCH STRAND

Anchor seperator

T N G H E L E F R E H O R A N C

g e ) ( c h a n

G H T D L E N O U N O R B H C N A

Fig. (1.35): Tie Back Anchors Method Statement

54

Fig. (1.36): Tie Back Anchors Stressing Testing

55

SECTION: 1


1.6

q)

Guide wall should be used to improve the lateral tolerance of the shoring systems execution.

r)

Loose- to medium – dense sands may undergo liquefaction during an earthquake. The depth of potential liquefaction should be assessed for the earthquake conciliations appropriate to the site. It may be necessary to carry the foundation of the retaining wall below the liquefaction zone, or compact the soil within the zone using deep vibro compaction (Seed H.B. et al (1983) and Ishihara (1993). BS 8002: 1994, Section 3.3.4.4.

s)

In shallow excavations or structures built adjacent to a tidal waterfront area, piping or uplift may occur due to water pressure differences generated by tidal action. Structures should be checked against instability from these causes.

t)

The normal tolerances in the formation of close bored pile walls should be maximum 1 in 75 to 1 in 100 for verticality and 50 mm for lateral plan tolerances measured at right angles to the line of the wall. (BS 8002: 1994, Section 4.4.7.5.1)

u)

The required verticality tolerance for secant piles is normally of the order of 1:200 and for positional tolerances of the order of 25 mm, where walls have to be constructed in close proximity to other structures. (BS 8002: 1994, Section 4.4.7.5.1)

v)

The safety and stability of nearby buildings and service should not be put at risk.

DESIGN GUIDELINES FOR BUILDING PILES 1.6.1

56

SECTION: 1


e)

Piles shall be designed with a minimum safety factor of 2.5.

f)

Uplift capacity of single pile is normally less than the friction capacity in compression (Poisson’s effect), and hence shall be taken not greater than 0.7 of the friction capacity estimated for compressive capacity.

g)

Considering horizontal force and bending moment resulting from out of position by 75 mm in horizontal direction at working level, and out of the plump (verticality) by 1:75 according to BS 8004: 1986, Section 7.1 and 7.4.5.4.8. Where the pile head is fully restrained by tie beams, pile caps or raft, the contribution of the restraining system shall be considered to the favour of pile design.

h)

Considering lateral load acting on pile as resulted from super structure analysis and shall be in the order of 5 % of the pile capacity at least.

i)

Elastic analysis to obtain the lateral straining actions using (Reese & Matlock).

j)

The stirrups of the pile shall be checked according to Table 3.8 of BS 8110, Part 1: 1997 and shall not be closer than 150 mm centres to ensure proper placing of concrete as per BS 8004 : 1986, Section 7.4.4.4.2.

k)

The length of steel bars anchored to the foundation to be according to Table 3.27 of BS 8110, Part 1: 1997.

l)

To prevent ingress of water and aggressive ground water penetrating the concrete, the design shall be to BS 8102 Type B using BS 8007 with a 0.20 mm crack width.

m)

Settlement calculations under the working loads to be provided. The expected value to be within 1% of the pile diameter.

n)

Assessment of pile group settlement shall be carried out by the foundation design Engineer and shall be compared to acceptance limits adopted for the project.

DESIGN CRITERIA FOR PILING WORKS a)

The permissible service stress should not exceed 25% of the specified cube strength at 28 days as per BS 8004 : 1986, Section 7.4.4.3.1

b)

The ultimate axial load should not exceed the value of “N” given in BS 8110, Part 1 : 1997, Section 3.8.4.3

c)

The minimum percentage of reinforcement shall be according to Table 3.25 of BS 8110, Part 1 : 1997

o)

Pile skin friction in sand should be reduced by 50 % in case of using bentonite as drilling slurry.

d)

Pile bearing capacity calculations as per (Tomlinson’s Pile Design and Construction Practice) as advised by BS 8004: 1986, Section 4.5.3. The different types of soil and the nature of shaft resistance when using bentonite, water or full length casing shall be taken into consideration. Negative skin friction should be added to the applied load in case of piles penetrating reclaimed soil.

p)

For friction piles the spacing should be not less than three times the pile diameter, and not less than twice the pile diameter for end bearing piles as per BS 8004: 1986, Section 7.3.4.2. Piles spacing is recomended to be minimum 2.5 times the pile diameter.

57

SECTION: 1

SECTION: 1


q)

For tension piles designed to resist the uplift forces or end bearing piles installed from ground level until deep bedrock, the reinforcement should normally be carried down for the full length. According to BS 8004 : 1986, Section 7.4.5.3.2

r)

The longitudinal reinforcement should extend at least 1.00 m below the bottom of casing so that movement of the reinforcement during extraction of casing is minimized. BS 8004 : 1986, Section 7.4.5.4.5

s)

A minimum additional allowance of 40 mm should be added to concrete cover recommended in Table 3.4 of BS 8110, Part 1: 1997.

t)

Cover spacers may be of pre-formed plastic to be used for the pile. The spacers should be threaded to lateral stirrups and should be spaced of not more than 2.0 m with minimum of three to be placed in each row. One set should be fixed at the pile cut-off level and one at approximately 1.0 meter from the toe of the cage.


2. Drill to the required depth

1. Install temporary casing concentric with the pile points.

3. Lower the rebar cage inside the drilled borehole.

Guide casing

4. Concreting using concrete pump and tremie pipe

5. Wit hdraw theguide casing.

6.Completed pile .

Fig. (1.37) shows the method statement for continuous flight auger piling as well as the drilled bored piles.

Fig. (1.38): Method Statement for Drilled Bored Piles

1.6.2

POINTS TO BE CHECKED DURING CONSTRUCTION, FIGS. (1.38 & 1.39) a)

If betonite slurry is used, the density should be less than 1.10 g/mL. The viscosity as measured by the Marsh Cone should be within a range of 30 to 90 seconds, and the 10 min. gel strength to be in the range of 1.4 N/m2 to 10 N/m2. The pH value should be maintained within a range of 9.5 to 12. BS8004: 1986, Section 6.5.3.8.1.

b)

The geophysical properties of the bentonite slurry should be re-established prior to the commencement of concreting operation. A submersible and circulation pumping system or air lifting system may be utilized for this purpose.

c)

If extensive bentonite slurry loss occurs during drilling, the drilling will be stopped immediately. The bore will be backfilled with

1 Augering

2 Ex tracting of Auger 3 Installing of Flights and Injection Steel Reignof Cement Mortar forcement

Drilled Bored Piles

Continuous Flight Auger Piling

Fig. (1.37): Method Statement for Different Types of Bored Piles

58

59

SECTION: 1


the excavated material in order to create a plug surrounding the pile shaft. Re-drilling will then take place. If further fluid loss or shaft collapse occurs, the bore will be immediately backfilled with low strength, lean mix concrete prior to any further excavation taking place. d)

Before Installing steal cage and casting concrete when reaching the pile toe level, loose and remolded material and debris will be removed with the drilling or cleaning bucket.

e)

High slump concrete of specified grade should be used according to Table 14 of BS 8004 : 1986

f)

For a continuous assurance of concrete quality and integrity, concrete should be poured to minimum 1.50 m above the theoretical pile cut-off level.

g)

h)

60

Casting of piles shall be performed as a continuous operation. The concrete should be designed to remain workable for a minimum of three hours from the time of the batching to the time of placement into the pile. The concrete shall be placed by tremie tube method; the tube diameter. shall not be less than 150 mm. The tube shall be inserted at the centre of the pile to reach the toe. The top shall be connected to a funnel. The concrete shall be delivered directly from the transit mixer to the funnel. The tube to be lifted 100 mm above pile toe level prior to concreting. While concreting, the length of the tube to be shortened if necessary but shall be maintained always into the concrete of at least 2.0 m length.

i)

Continuous supervision on site by engineer and the contractor is always necessary to ensure that the piles are properly executed.

j)

Care to be taken to ensure that there will be no displacement or distortion of reinforcement during the formation of the pile.

SECTION: 1


1.6.3 PILES TESTING Piles testing shall conform to the following minimum requirements: a)

At least one for each pile diameter, non-working pile shall be tested, to 200% of the pile’s working load. BS 8004:1986, Section 7.5.5 or ASTM D 1143/1143M. Osterberg cell can be accepted only in the preliminary test.

b)

1 % of the total number of working piles and minimum one test for each pile diameter/type shall be statically tested to not less than 150 % of the pile’s working load, BS 8004:1986, Section 7.5.5 or ASTM D 1143-89.

c)

5 % of the total number of working piles shall be tested using high strain dynamic method to not less than 150 % of the pile’s working load. ASTM D 4945-89.

d)

10% of the total number of working piles shall be tested using cross- hole sonic core logging test method for piles of diameter equal or more than 600mm. ASTM D 6760-08.

e)

100 % of working piles shall be tested by using low strain dynamic integrity test and shall be repeated for piles statically tested. ASTM D 5882-07.

f)

The following procedure shall be followed for particular tests whenever are required by the project specification or design conditions: -

Pile instrumentation test should be performed on tested pile(s). The test shall be performed at the time of static load test for piles of diameters 1000 mm or more.

-

Static laterally loaded piles test should be conducted where the lateral loads governing the design.

-

Static tension pile test should be conducted where tension piles are used to resist uplift.

-

10 % of working piles boreholes and all preliminary & statically tested working piles are to be selected randomly and tested by mechanical calliper logging (ASTM D 6167 – 11 & ASTM D 5753 – 95e1).

-

Steel reinforcement and concrete strength and durability shall be tested as per QC Guidelines.

61

STRUCTURAL DESIGN GUIDELINES – BUILDING STRUCTURES

62

02 SECTION

63

N O I T C E S

2


SECTION: 2


2.4 2.1

INTRODUCTION Structural guidelines listed below shall be applied to all building structures and are intended to provide minimum structural design requirements for building sub and super structures. Please refer to the applicable codes for detailed technical guidance and requirements. The guidelines are aimed to give the design engineers a general idea of the basic requirements in designing the structures to comply with the CED-Trakhees regulations and the relevant building codes. It is anticipated that the use of these guidelines will result in a uniform design and construction of buildings throughout projects in CED-Trakhees jurisdiction. Any requests for variations to the guidelines presented must be fully documented and presented to the CED-Trakhees for review and acceptance prior to any application.

2.2

DESIGN OUTCOME The design shall meet all relevant standards for safety, durability, fire resistance and serviceability. The designer shall investigate alternative systems and shall achieve optimized economical and constructible solution.

2.3

SUSTAINABILITY AND ENVIRONMENTALLY RESPONSIBLE DESIGN Design should satisfy sustainability and environmental guidelines adopted for the project. The following should be taken into account in structural design approach:

64

1)

Consultant shall propose a design maximizing the use of environmentally friendly and energy efficient technologies in material and construction techniques.

2)

Designer should consider climate change implications within the design life of the structure and accommodate them by adopting adequate design parameters and detailing.

3)

Where possible, consultant shall maximize the used of recyclable and recycled construction materials.

4)

Consultant should specify locally manufactured materials as a first preference where possible.

5)

Proposed design should involve a minimum level of disruption to the natural environment.

6)

Consultant should maximize the use of clean and non-destructive construction technologies including off-site pre-fabrication.

APPLICABLE CODES The following codes with listed parameters shall be permitted for the purpose of structural design. Technical codes not listed in this document shall be submitted for review and approval prior to adopting in the design. Consultant should ensure that selected design standards are the latest editions and fully compatible with CED’s design regulations & guidelines.

2.4.1

DEAD AND LIVE LOADS 1.

BS 6399: Part 1 ‘Loading For Buildings: Code of Practice for Dead and Imposed Loads’.

2.

BS 6399: Part 3 ‘Loading For Buildings: Code of Practice for Imposed Roof Loads’

3.

ASCE 7: ‘Minimum Design Loads for Buildings and Other Structures’, Chapter 3 ‘Dead Loads’ and Chapter 4 ‘Live Loads’

4.

Adopted dead and live loads shall satisfy recommendations of the Dubai Municipality, CED - TRAKHEES and other relevant statutory authorities.

2.4.2 SEISMIC LOADS 1.

UBC 1997, Volume 2, ‘Structural Engineering Design Provisions’, Division IV ‘Earthquake Design

2.

Zone 2A shall be adopted for all structures.

3.

For special structures, ‘Recommendations for the Seismic Design of High-rise Buildings’, CTBUH 2008, shall be adopted.

2.4.3 WIND LOAD 1.

ASCE 7: ‘Minimum Design Loads for Buildings and Other Structures’ - Chapter 6. Design shall be based on basic wind velocity of 45 m/s.

2.

For all structures where wind loads are applied as per codes, other directions than the two orthogonal ones to be investigated for ultimate and serviceability limit states. The same shall be carefully studied for irregular buildings.

3.

Reliable wind tunnel study reflecting climatic site conditions shall be permitted as an alternative method of estimating wind loads. Wind velocity shall reflect historic wind record for the respected site. The wind loads resulting from wind tunnel test shall satisfy the requirements of ASCE 7.

65

SECTION: 2


2.4.4 DESIGN CODES

2.5


4.

Applied standards in loading and design.

5.

Materials properties: Concrete & reinforcement grades, modulus of elasticity, shear modulus, density of block works, etc

6.

Fire resistance requirements: Fire rating, concrete cover to reinforcement, minimum reinforcement, etc

7.

Durability requirements: Design life of the structure, concrete quality for sub and super structure, minimum cover to reinforcement, protection measures for concrete below and above ground, crack width & deflection control.

1.

BS 8110: ‘Structural Use of Concrete’

2.

ACI 318: ‘Building Code Requirements for Structural Concrete’

3.

ACI Manual of Concrete Practice – the latest edition.

4.

AISC 360

5.

UBC 1997, Volume 2, ‘Structural Engineering Design Provisions’

6.

BS 8004: ‘Foundations’

7.

BS 5950: ‘Structural Use of Steelwork in Buildings’

8.

BS 8007: ‘Design of concrete structures for retaining aqueous liquids’

8.

Robustness requirements as per relevant standards.

9.

BS 5628: ‘Code of Practice for Use of Masonry’

9.

10.

IBC ‘International Building Code’, excluding seismic design provisions.

Damping: Proposed damping value for seismic design, damping value for wind loading and occupancy comfort control.

10.

Analysis and design Software, spreadsheets used for design or/and verification, etc

11.

Detailed calculations shall include:

PERFORMANCE CRITERIA The following modelling and design criteria shall be followed.

2.5.1

DESIGN LIFE

a.

Gravity loads correspond to different floors.

1.

b.

Basic seismic parameters estimate.

c.

Weight of the building for seismic calculations.

d.

Static base shear.

e.

Vertical component of seismic loads.

f.

Disconti nuity and vertical irregularity considerations.

Unless otherwise specified, 50 year design life of the structure shall be adopted.

2.5.2 COMPUTER MODELS, STRUCTURAL ANALYSIS AND DESIGN REQUUIREMENTS 2.5.2.1 STRUCTURAL ANALYSIS AND DESIGN

The designer shall submit detailed design criteria as well as design assumptions and should contain at minimum, the following information (Wherever is applicable): 1.

Description of the site: Location, BU name, plot number, project ID, etc

2.

Description of building: Building size, height, basements, podium floors, typical floors, setbacks, floors use, etc

3.

66

SECTION: 2

Description of structure: Foundation type, vertical members, lateral forces resisting system, floor slabs scheme, building separations, etc

g.

Accidental torsion calculations.

h.

Directional effect of seismic loads.

i.

Scale factors calculations.

j.

Interconnection requirements

k.

Wind loads parameters and coefficients or wind tunnel study report.

l.

Basic load combinations for ultimate and service states design.

67

SECTION: 2


12.

Extracts from analysis outputs: Modal mass participation ratios, tension stresses in shear/core walls and modifiers corrections, wind tunnel and code forces comparison, total and inter-story drifts calculations, vi bration acceleration calculations, deflections and crack control calculations.

13.

Software analyzed computer models conducted as per CED’s requirements.

14.

If applicable, third party report confirming the full compliance of the submitted design documents with the design provisions of the applicable codes and CED’s design guidelines. The report shall be conducted as per the relevant CED’s guidelines and requirements.

SECTION: 2


lyzed considering realistic base restraint conditions for cores, shear walls and columns. Adopted boundary conditions shall be reflected in the design and detailing of sub and super-structure members. 7.

Modulus of elasticity shall be calculated as per the code governing the design.

8.

The analyzed computer model shall be free from any major warnings or errors.

9.

Section modifiers shall be applied as per clause 1910.11.1 of UBC-97.

10.

Soil profile type and other seismic parameters used in seismic analysis shall be as recommended in the geotechnical investigation report.

11.

Iterative method of estimating P-Delta effect shall be considered in the analysis of buildings as requested by clause 1630.1.3 of UBC 1997. Minimum of 3 iterations shall be used.

12.

Structures and buildings shall be analyzed by employing Response Spectrum Analysis in full compliance with UBC 1997.

13.

Tall buildings and other structures with structural system sensitive to construction sequence shall be investigated for the effects of construction sequence on internal load distribution.

14.

The design seismic case shall consist of combination of two orthogonal excitation directions combined on the SRSS basis as requested by clause 1633 of UBC 1997.

2.5.2.2 COMPUTER MODELS

1.

The 3D model should reflect the actual geometry of the structure / building and shall be in full compliance with the design criteria and assumption.

2.

The finite elements meshing shall appropriate to software used for analysis. The designer shall ensure that the analysis results are not affected by the quality of meshing.

3.

The computer model shall have proper meshing of slab and wall elements. For walls and slabs. The meshing should have rectangular bias with elements of aspect ratio not exceeding 2:1. Where openings are provided in the slab or wall elements, the mesh nodes shall be located at the corners of openings.

4.

68

The designer shall ensure proper connectivity for slab elements (Joints/Corner of one element should not be connected to edge of other element, unless appropriate calibration analysis is submitted with the model). The mesh shall also have proper connectivity with columns and walls elements.

5.

Appropriately set-up auto-meshing could be used for regular rectangular buildings. Care should be given to connectivity and meshing constraints.

6.

The computer model of concrete buildings shall be ana-

2.5.2.3 GENERAL CONSIDERATIONS

1.

Where the structure is composed of a flexible upper portion and lower stiffer basement/podium, the seismic scale factor shall be calibrated at foundation level to design the basement elements and at top of basement to design the tower elements.

2.

The augmented section modifiers could be used to check the maximum drift and vibration acceleration only as

69

SECTION: 2


permitted by ACI, provided that the designer has to estimates the degree of cracking and comply with the serviceability limit state at the adopted design service loads. 3.

Permanent drift due to gravity loads to be checked and shall be eliminated or minimized with proper technical arrangement.

4.

All structural framing elements and their connections, not required by design to be part of lateral–force-resisting system, shall be designed to be adequate to maintain support of design dead plus live loads when subjected to the deformation caused by seismic forces.

5.

6.

Manual take down of gravity loads for all key vertical elements to be compared with resulting loads from analyzed model.

7.

Design shall be carried out in accordance with code the governing load combination was derived from.

8.

Calculation of effects of accidental eccentricities and load reductions shall be consistent with the code used for the structural design.

9.

Thermal effects shall be evaluated based on realistic temperature distribution. Seasonal temperature change shall not be less than 25 deg C or in accordance with credible local climate record. This effect shall be considered in design of v ertical and horizontal members.

10.

11.

70

Effects of axial long term shortening due to elastic, shrinkage and creep effects shall be investigated and accounted for in the design and construction. If measures to compensate for the effects of differential shortening are taken, consultant shall include such information on engineering drawings and relevant documents.

Structural design shall accommodate shrinkage, creep and thermal strains by providing appropriate reinforcement or specifying control or expansion joints. Expansion joints shall satisfy seismic requirements of relevant code. Floor slabs shall be designed to be adequately supporting the entire construction loads from the next slab without compromising the ultimate or/and service limit states requirements.

SECTION: 2


2.5.2.4 SERVICEABILIT Y LIMITS

1.

All buildings shall be designed to limit maximum drift under 50 years wind load to 1/500 of building height.

2.

All buildings shall be designed to limit inter-story drift to 1/500 of the story height and not more than 10mm under serviceability of 10 years wind. If no wind tunnel test results are available, 10 years serviceability wind speed of 38 m/s can be adopted in Dubai for inter-story drift calculations.

3.

Adequate provisions shall be adopted to eliminate risk of damage to non-structural elements due to inter-story drift.

4.

Wind induced vibration due to 10 years wind shall be limited to 15 milli-g for residential and hotel buildings and 20 milli-g for office buildings. Damping ratio should under no circumstances exceed 2.0% unless additional special damping devices are used. For buildings subject to coupled modes response, the torsional velocity due to 10 years wind shall be limited to 3 milli-rad/s or as recommended with credible relevant reference.

5.

For buildings with irregular façade shapes and where a potential noise expected to occur, the tonal noise generated as part of vortex shredding mechanism shall be properly addressed by wind specialist. The consultant and the wind specialist are solely responsible to undertake the necessary study and to propose any effective remedial measures to resolve the problem.

2.5.2.5 SOFTWARE

The following commercial structural software packages are commonly used structural design tools and are accepted by CED for structural analysis and design. Computer software not listed below shall be submitted for review and approval prior to adopting in the design. Acceptable popular commercial structural software packages: ETABS, SAFE, SAP2000, ROBOT, STRAND, STAAD, PROKON.

71

SECTION: 2


SECTION: 2


Municipality. A copy of their Trade Licence needs to be enclosed. These drawings after checked by consultant shall be stamped and signed by them and submitted to CED along with a guarantee l etter stating that they have verified the designs of the specialist contractor and they take full responsibility for the same.

2.5.2.6 UNIT SYSTEM

All structural calculations, computer output, technical reports, specialist consultant recommendations and drawings shall be presented in SI unit system. All dimensions on structural drawings shall be presented in millimetres.

2.6

STRUCTURAL CALCULATIONS

11.

Soil investigation report certifying all soil parameters conducted by an approved soil specialist agency as per CED’s geotechnical guidelines.

12.

To resist the Seismic loads, joint ductility, confinement of concrete and joint framing connection details shall be as per the requirements of relevant approved codes. The reversal of stresses in structural members shall also be taken into account and proper detailing to be made along with supporting calculations.

All calculations shall be submitted in soft copy in pdf format arranged in sequence according to the index sheet. The Structural Calculations shall generally include but not limited to the following: 1.

Index sheet with contents and page numbers.

2.

An introduction containing the project ID and briefly outlining the submission purpose together with the list of drawings, calculations, reports, etc.

STRUCTURAL DRAWINGS The Structural Drawings shall generally include but not limited to the following information:

3.

Design philosophy; reference Codes, complete design criteria and assumptions for loads, height of building, number of fl oors, etc.

4.

Column load calculations by area method & reaction method.

a.

Standard abbreviation and symbols.

5.

Stability analysis for wind and seismic loads including checking for allowable drifts. For wind induced accelerations, a check for human comfort criteria is to be enclosed.

b.

6.

Loads on columns, shear walls including wind and seismic moments are to be marked in the copy of foundation layout for critical load cases.

Reference to Soil Investigation Report indicating the safe bearing capacity, depth of foundation, soil improvement, number of floors for which foundation has been designed. The number of floors shall comply with approved architect concept drawings.

c.

General information and details shall include:

7.

Serviceability checks for deflection, crack width to be included where applicable.

8. 9.

10.

72

2.7

Reinforcement calculations for beams, slabs, columns and shear walls. In case if design is done using software, sample pages are to be enclosed. Soft copy of all the calculations copied in a CD as well as software models shall be submitted. All software models shall be run and free of errors. At the time of joint review, the consultants shall bring a laptop PC installed with the design software to check the building model. In case modelling has been done using ETABS, SAFE, SAP, ROBOT, etc., consultant shall submit only extract pages in PDF format of selected important input and output data that may facilitate the review process. In case of specialised works such as post tensioned slabs, tent structures, large span timber structures, prefabricated steel structures, the structural designs and drawings for these works shall carried out by specialised consultants having an approved valid trade licence from Dubai

1.

General Notes drawings containing the following details:

1)

Details of water proofing systems.

2)

Earthworks and dewatering instructions.

3)

Strength, density of block works, blocks works construction details and construction sequences.

4)

Typical details of RC connections.

5)

Typical reinforcement curtailment/arrangement of columns, slabs, beams, floating slabs, manholes and water tanks typical details.

6)

Standard lintel details.

7)

Construction and movement joints details.

8)

Mechanical pipes penetration details, extra reinforcement around openings, trenches, cable trays and trans-

73

SECTION: 2


SECTION: 2


documents shall be passed to CED under the lead consultant covering letter.

formers base details. 9) 10)

d.

e. 2.

Details of inserts to concrete, holding down bolts, plinths and up stands/down stands elements.

Fire resistance rating for different structural members, reinforced concrete specifications for all exposure conditions, specifications of other concrete types if used, concrete grades of reinforcement, concrete cover to reinforcement, concrete protection. Materials information shall comply with QA & QC guidelines.

4.

Columns, Shear walls and Core walls: General Arrangement drawings showing walls layout, thicknesses, elevations and openings are to be submitted. Detailed sectional plan and sectional elevations for lift and core walls showing the reinforcement in the walls, around openings, corner bars, spandrel beam details and wherever is necessary to be provided.

Column Axes plan Drawings: 7.

Floating columns/walls and transfer beams/slabs structures: The sizes of floating elements along with their locations are to be marked in plan drawing. Sectional elevation showing the columns/walls below and above the transfer structure has to be drawn. The transfer structure sections shall include the reinforcement details of all members and connections and any special provisions may be required by the design or construction.

Foundation Drawings:

8.

Staircases: Detailed plan, sections and reinforcement drawings for staircase are to be submitted.

9.

Swimming pools: Detailed GA plan and sections for swimming pool indicating the levels and supporting arrangement including floating columns, if any. Adequate sections are to be drawn to show reinforcement in base slab, walls, deck slab, etc.

Floors Slab Drawings: General arrangement showing the thicknesses of slabs, openings in slab and their sizes, floor levels etc are to be submitted. Reinforcement details are to be drawn in plan and as well as in typical sections. Extra top and bottom reinforcement and shear resisting steel shall be properly detailed. In case of Post Tensioned /Hollow Core Slabs, drawings shall be prepared by specialist consultants having the necessary valid Trade license. The specialist drawings shall be reviewed with the relevant calculation, signed and stamped prior to submission to CED. All specialist

74

6.

Design criteria of any other unconventional slab system, if applicable.

Plot limit line is to be marked in the foundation plan. The Piled Raft / Raft foundations drawings shall contain general arrangement showing plan, sectional elevations with levels, Reinforcement plan showing top and bottom steel, extra top and extra bottom steel and any shear resisting reinforcement as per design requirements. Sections shall be drawn through lift pits, drain sumps and pour strips showing the arrangement of reinforcement. The foundation drawings shall also show starter bars for columns/walls as per design requirements. Arrangements and sections details of movement, settlement joints as well as water stoppers details to be provided, if applicable.

Beams reinforcement drawings: Schedule for beam sizes and reinforcement with adequate sections are to be submitted. The amount and location of longitudinal reinforcement, stirrups, side bars, torsional bars as well as sectional details of the special beams, parapets, corbels, connections wherever is necessary to be provided.

Loads considered in design of different floors, mechanical floors, transformer & LV room area, chillers and compressor areas, etc

Column/ walls axes plan showing the reduction in column/wall sizes. All columns/walls shall have grid markings. Grid lines in structural drawings shall match with architectural drawings. 3.

5.

10.

Non structural architectural features: The architectural features constructed from concrete or any other materials shall meet all the relevant stability, durability and constructability requirements.

11.

All the structural drawings shall have a standard title block containing the project name, the plot number, BU’s name, cli ent name, name of the

75

SECTION: 2


lead consultant, drawing title, key plan identifying the area relevant to the drawing subject, full record of different revisions, etc

76

12.

All the structural drawings shall be cross referenced as much as possible.

13.

All the structural drawings shall be signed and stamped in standard location of the drawings. Typical space shall be left for CED stamping. If applicable, all the submitted drawings shall be signed and stamped by the third party consultant.

14.

All the structural drawings required to be approved from CED shall be combined together in PDF binder and shall be properly oriented as well as arranged in order.

77

GUIDELINES FOR PRE STRESSED CONCRETE WORKS (SLABS)

78

03 SECTION

79

N O I T C E S

3

SECTION: 3



3.2 3.1

GENERAL The current pre stressed guidelines is relevant to the post tensioning bonded systems only, Fig. (3.1), whereas the other pre stressed systems shall be submitted for review and approval prior to work. Post tension specialist contractor has to take approval from CED, to work in post tensioning field prior to commencement of any work; the specialists will be given a tolerance of 3 months to comply with the guidelines requirements. Beyond the above period, no work will be permitted without CED pre approval of the full PT system as described hereinafter.

PRE STRESSED CONCRETE SYSTEMS APPROVAL Pre stressed concrete specialist contractor shall have qualified international recognized pre stressing system to perform in accordance with its materials and technical requirement. The specialist contractor shall have exclusive agency agreement with the system provider including providing the local specialist with materials, all necessary technical support, and skilled manpower wherever is needed. Such agreements shall be registered and approved from relevant statutory authority as appropriate. And shall be yearly renewed, or confirmed by letter from mother system agency if the period of agreement is more than one year The specialist contractor has to follow CED’s procedure to get final approval for the system as per the procedure. Each approved system will be registered under identification number called PTS number.

3.2.1

Vent pipe Formed sleeve

Oblong sleeye pipe Mastic

APPROVAL OF MATERIALS

Vent pipe

a)

Bulb

Oblong sleeve pipe

Flat duct

Mastic

Approval of anchorage system, Fig. (3.2).

Specialist contractor shall submit initially certificate of origin, material catalogue and full sample supported with technical data sheet, with no more than one year old.

Flat duct

0 0 1

950

300 300 400 w Steel Plate 0 5 5 7 2 3

0 0 0 0 1 2 3 L 0 5 5 5 1 2

:

:

3 5 1 1 T T

80

80

55 55 55 55

55 55 55 55

260

260

Fig (3.2) Anchorage system b)

Fig (3.1): Pre stress bonded system

Pre stressed concrete equipment approval :

Specialist contractor shall submit the technical data for pre stressing equipment which will use in the works. Jacks, hydraulic pumps, dead end machine, grouting machine, and Duct machine (If applicable), all are required to be approved, Fig. (3.3). The submission should include the calibration test for the jacks. Hydraulic jacks calibration should be submitted for each project, the calibration should be dated not more than 6 months prior to submission date.

80

81

SECTION: 3

SECTION: 3



mitted, the size should have relation with the number of strands, and the net clear area should be more than twice the ducts cross sectional areas.

Dead end machine

Hydraulics Pump

Stressing Jack

Grouting machine

Stapler gun

Duct Machine

Fig. (3.3) Pre stress equipment c)

Corrugated and flat galvanized metal ducts will be accepted, Fig. (3.5).

Fig. (3.5) Ducts e)

Approval of Duct Chairs, Fig. (3.6):

Chairs should be machine made and have epoxy coating for support parts and at least up to 20mm over the forms; Chairs shall be according to the specialist shop drawings, and not less than 6mm Diameter.

Approval of Strands, Fig.(3.4):

Specialist contractor shall apply for the strands supplier approval along with mill certificates. Confirmation sample composed of both anchorage and strands simulating the site execution shall be submitted for approval. Only one supplier shall be approved for the same project. *Note: It is mandatory for the strands supplier to obtain D.C.L. Quality Mark.

Fig. (3.6) Ducts Chairs f)

Approval of shear stud :

Shear stud should be used in slabs with less than 200mm thickness. Specialist contractor should submit these materials for approval; stud materials should be from specialized qualified factories, Fig.(3.7). Fig. (3.4) Pre stress strands d)

Approval of ducts:

Specialist contractor shall apply for the ducts supplier approval along with all specifications and certificates. Thickness of duct should not be less than 0.4mm. Ducts type, thickness and size should be approved according to sample sub-

82

Fig. (3.7) Shear stud

83

SECTION: 3


g)

SECTION: 3


Approval of Grouting material :

for registration.

Specialist contractor shall submit grouting mix design for approval, the mix should contain: cement, water, along with shrinkage compensating materials (Refer to Trakhees Construction Material Quality Control Guidelines), and elevate admixture in order to achieve minimum 28 days grout strength with maximum accepted tolerance of 12 N/mm2 from concrete characteristic strength.

1-

CED approval for the site engineer/s will be subject to passing the written exam and technical interview with satisfactory result.

2-

Each site engineer will be permitted to supervise a predetermined number of projects simultaneously. The following limitations are given for guidance and CED may request to reduce these figures in cases where the quality of works revealed to be unsatisfactory and hence the specialist will be asked to submit another site engineer/s for approval.

3.2.2 REGISTRATION OF PT SPECIALIST: The registration of PT specialist could be ensured provided that the below technical staff have been successfully tested and interviewed as per the procedures. Each approved specialist will be registered under identification number called PTC number. a)

The following figures may be permitted for each approved site engineer subject to the periodic performance evaluation.

Approval of project manager/s

Specialist contractor shall submit the C.V of the project manager/s for registration, it may be required to be tested in writing, and/or interviewed by CED relevant committee.

5 years --------------------- 2 structures running simultaneously. 6 years-- ---------- ------- 3 structur es running simultaneously.

Project manager shall have minimum 10 years experience. b)

Above 6 years --------- - 4 structures running simultaneously. 3-

Approval of design engineer/s:

Specialist contractor shall submit the C.V of the design team for registration. CED approval for the design engineer/s will be subject to passing the written exam and technical i nterview with satisfactory result. Designer engineer/s may be requested to confirm the specific involvement in the PT design field through a realistic exercise prior to decide the final success. 1-

Each designer will be permitted to conduct the design for an assigned annual PT quantity, if the work volume is exceeding, the specialist will be asked to submit another designer for approval.

3.2.3

2-

c)

The designer should have minimum 5 years experience in the structural, and at least three years of them in post tensioning design in recognized P.T Specialist agency.

Approval of site engineer/s:

STORAGE OF MATERIALS Specialist contractor has to submit the storage area for approval and shall be suitable to store the PT materials in good condition with minimum covered area of 200 m2. Method statement of materials storage shall be submitted for approval.

3.2.4 APPROVAL OF METHOD STATEMENT Specialist contractor has to submit the method of statement in prof essi onal details for approval, from receiving of materials till handover the grouting and shuttering removal; this shall be included in each project submission.

The Quantity of PT work may be permitted for each approved designer, has to be within the following figures: 600,000 m2/ annum and not more than 100,000 m2 / month.

The site engineers should have at least 5 years total experience includes one year actual experience in PT execution field.

3.2.5

PERMISSION TO THE FIRST PROJECT Specialist contractor shall submit the concept of first project for approval in principle. 1-

Upon the concept approval, the speciali st shall submit the detailed design for approval, CED shall be notified in advance of the date of executing of each slab, CED’s engineer has to take the

Specialist contractor shall submit the C.V of the site engineer/s

84

85

SECTION: 3


SECTION: 3


necessary action to check and approve the work at site prior to concrete placing.

3.3

2-

After hand over the post tension work to the respected party, the specialist contractor shall apply to the CED for final inspection.

3-

Based on final inspection, CED will decide the final approval of the specialist and the system as well.

4-

All the above procedures shall be submitted to CED under the lead consultant cover letter.

f.

ASCE-7-5

g.

IBC-latest edition.

3.3.2.2 GENERAL CONSIDERATIONS a.

Slab Thickness

1.

Slab thickness should be decided based on the loads and spans.

2.

For normal loads in residential and commercial areas, the thickness of flat slab should be proposed to be as explained in Fig. (3.8) provided that the ultimate and service limits requirements are met.

3.

Vibration shall be considered in the design of the offices areas, following the above mentioned codes.

4.

Cubic strength for the concrete used in pre stressed slabs shall not be less than 40 N/mm2.

SOFTWARE APPROVAL & DESIGN GUIDELINES 3.3.1

SOFTWARE APPROVAL Specialist contractor/consultant shall use licensed software only. Software used by the specialist contractor require CED certification and approval prior to implementation in the design. The software could be certified and approved following the below procedures: Specialist contractor shall submit original license for the software, along with user technical manual and all related technical sheets, via cover letter from the specialist. To ensure a better understanding of the software capability and performance enhancement, the specialist shall respond to all CED enquiries and if necessary to conduct a technical demonstration or/and presentation as per the CED arrangement. The specialist contractor will be notified on the final approval of the software as per the relevant discipline.

3.3.2

DESIGN GUIDELINES

Total imposed Span/depth ratios load 6m < L < 13 m (kN/m) (kN/m)

Section Type 1. Solid flat slab

2.5 5.0 10.0

40 36 30

2. Solid flat slab with drop panel 2.5 5.0 10.0

44 40 36

span/5

4. coffered flat slab

3.3.2.1 APPLIED DESIGN CODES

The following codes and report are permitted for design of post tension slabs. Unlisted codes shall be submitted for approval prior to use in design.

86

a.

BS 8110 1997 structural use of concrete.

b.

Technical Report (TR 43).

c.

ACI-318 latest edition.

d.

Post Tension Manual, fifth and sixth edition.

e.

Euro code 2.

6. coffered slab with band beam

> span/6 7. Ribbed slab

> span/3

3. Banded flat slab

Slab

Beam

2.5 5.0 10.0

45 40 35

25 22 18

2.5 5.0 10.0

25 23 20

5. coffered flat slab with solid panels 2.5 5.0 10.0

Section Type

Span/depth Totalimposed ratios load 6m < L < 13 m (kN/m) (kN/m)

2.5 5.0 10.0

28 26 23

2.5 5.0 10.0

30 27 24

8. One-way slab with narrow beam

2.5 5.0 10.0

Slab

Beam

42 38 34

18 16 13

> span/15

28 26 23 (3.8) Slab thickness Fig.

> span/3

b.

Concrete cover

1.

Concrete cover shall comply with durability or fire resistance requirements, whichever condition is the more onerous.

2.

The cover shall be measured to the outside surface of the duct; the minimum net cover for bonded

87

SECTION: 3

SECTION: 3


3.

c.


system shall be 35 mm.

5.

Strands shall not be extended from level to another.

Requirement for the other pre stressed tendons shall be as per Section 6 - Technical Report TR43, second edition.

6.

Tendons shall be avoided to be stopped inside the slab without support at ends. Support can be drop or hidden beams, walls or columns.

d.

Tendons

1.

The maximum tendon spacing shall not be more than 8 times the slab thickness or 1.5 m whichever is lesser. In case the banded distributed system is used, tendon spacing should not be more than 10 times the slab thickness in the banded direction. Banded direction where at least 2 duct with 3 strands/duct at least, are passing the columns areas. Column area shall includes the area bounded within distance equal to 0.5 slab thickness all around the column perimeter, otherwise distributed system shall be considered in the respected direction, Fig. (3.9).

evently spaced tendons in span

banded tendons over columns

evently spaced tendons for short span banded tendons over columns for long span

e.

Loads

1.

Design loads shall comply with project design criteria, BS 6399 and ASCE-7-05 requirements. In no cases, the live load should be l ess than 2.5 KN/m2.

2.

Jacking force should be taken as per design code and should be not more than 80% of breaking loads.

Deflection control

1.

Factors related to short-term elastic deflection estimation are as per Fig.(3.10):

2.

Pre cambering is not allowable in the PT slabs.

Loading

Factor related to shor-term elastic deflection value

Dead

3.0

Post-tensioning (after losses)

3.0

Live

1.5

Fig. (3.10) Factor taking account of long term effects Fig. (3.9) Banded-distributed systems 2.

88

Wherever there are certain difficulties to comply with the strands distribution basis, partial pre stressed slab shall be used provided that the PT strands to be compensated with designed conventional steel in the proper l ocations and directions.

3.

The minimum horizontal spacing between the ducts is the greater of 75mm or duct width.

4.

Curved tendons are to be avoided, but in case of difficulty to furnish the straight tendons, hair pins should be used in additional to bottom and top steel mesh not less than T10-200 mm, the curving shall not exceed 1:12.

f.

Conventional reinforcement in the pre stressed slab.

1.

The minimum bottom shrinkage mesh shall be applied by using T10 each 300mm.

2.

All support areas shall have the applicable code specified minimum reinforcement in the top for purpose of distributing the cracks and strength design requirements.

3.

Conventional reinforcement should be placed along edges of all slabs; this should include U-bars laced with at least tow longitudinal base top and bottom, Fig. (3.11).

89

SECTION: 3

SECTION: 3


‘ U ’bar


flexural and restraining reinforcement restraining reinforcement prestressing tendon slab

Bottom bar

5.

Transfer slabs or beams shall be of RCC only, pre stressed tendons could be used to reduce the deflection only.

6.

It should be noted that after stressing the bonded system and before grouting has taken place, it should be considered as un-bonded system.

7.

Grouting should be done at least three days before removing the scaffolding. If the grouting has placed after removal of the scaffolding, the design should be checked as un-bonded system.

8.

P/A should be not less than 0.7 MPa as an average value, If the average precompression exceeds 3.0 MPa, the design engineer shall explicitly recognize and account for the consequence of shortening of the member in connection with the restraint of the member’s supports.

9.

In members where early stressing is desired to reduce the risk of early shrinkage cracking, it is common to stress the tendons in two stages. The first stage is usually about 25% of the final pre stress force, and is carried out as soon as the concrete has gained adequate strength for the anchorage being used. This concrete strength could be between 10 and 15MPa. It is important that sufficient site-cured cubes or cylinders are provided to determine the transfer strength.

10.

Where prestressing is seating be wedges a minimum value of draw in value of 6mm should be used in the design calculation.

11.

Where a slab or system of secondary beams is stressed across primary beams, attention must be given to the sequence of stressing in order to avoid damage to the formwork of the primary beams.

wall

Transverse bar

Fig. (3.11) U-Bar at the edge of slab and junction of wall and slab

4.

All columns should be checked for punching shear, manually or by using applied software.

5.

Anchor bursting reinforcement should be added to resist the tensile stresses caused by the concentration of the force applied at the anchors, Fig. (3.12).

Fig. (3.12) Anti Burst steel at dead and live ends

g.

General

1.

90

Temperature and lateral force analysis should be done by 3-D building model, Pre stressed programs shall be used for gravity loads analysis only.

2.

Bottom steel at columns and support locations should be not less than 30% of the top steel at the same location.

3.

Elongation of the strands should be submitted with design drawings in separate sheet.

1.

4.

The accepted deviation between site recorded elongation and software output elongation shall be within ±10%.

CED-Trakhees has the right to cancel any previously approved post tension system in case experienced several defect during the system application.

2.

CED-Trakhees has the right to cancel any designer registration, if the same did not perform satisfactory.

3.4

GENERAL NOTES FOR SPECIALIST & SYSTEM APPROVAL

91

SECTION: 3


3.5

3.

CED-Trakhees has the right to disqualify previously approved supplier in case declination in product quality was noticed.

4.

CED-Trakhees can limit the work quantity for any specialist contractor based on the performance quality of the work that will be evaluated from time to time.

5.

All the submission of above subjects should be passed to CED via standard cover letter cross referring to PTC & PTS, valid trade license, in PDF format.

SECTION: 3


ricate pre cast concrete elements to the requirements of standards. The storage, transportation, handling and erection of the pre cast elements shall be carried out in conjunction and coordination with other construction activities as well as the respected standards controlling such kind of construction systems, Fig (3.13). Pre cast specialist should be registered in CED with certain products as follows:

DOCUMENTS REQUIRED FOR OBTAINING PRESTRESS PERMIT 1.

Consultant cover letter indicating the submission subject and description of submission purpose , project ID, specialist and system IDs, details of attached documents, etc

2.

Specialist document: prequalification-trading license- system approval, designer approval, site engineer, etc…

3.

Undertaking letter from specialist for pre stressing work (design and execution) approved by the consultant.

4.

Design criteria explaining all design data.

5.

Software license copy.

6.

PDF detailed drawings signed and stamped by specialist and consultant. DWG drawings are required for review purposes.

7.

List of submitted drawings.

8.

PDF calculation signed and stamped by specialist and consultant, including gravity, lateral force and thermal calculations (If any).

9.

3D models of the full structure to check the lateral force effects on P.T slabs design.

10.

P.T software models.

11.

Latest approved structural drawings.

12.

Third party report (If applicable).

I-Beam

Inverted Tee Beam

92

Ledger Beam

Pile sections

Column

Rectangular Beam

Hollow-Core Slab

Sheet Pile

Double Tee

Fig. (3.13) Common Precast Concrete Products 3.6.1.1 DOCUMENTS REQUIRED FOR PRECAST SPECIALIST REGISTRATION 1-

Valid trade license.

2-

Detailed information about the products, inclusive concrete, steel, pre stressed materials, etc….

3-

Applied codes and design criteria.

GUIDELINES FOR PRE CAST CONCRETE WORKS 3.6.1

Bulb Tree

Slab

4-

3.6

Box Beam

Method of statement for production, transportation, handling and installation.

PRE CAST SPECIALIST REGISTRATION

5-

CVs for designers and site engineers.

Precast concrete elements shall be produced by certified manufacturers, with certification demonstrating the capability of a manufacturer to fab-

6-

Quality assurance and quality control procedures.

7-

Test certificates, design mix… and full scale test.

93

SECTION: 3


8-

SECTION: 3


List of projects already completed successfully with the same product/s.

3.6.2 PRE CAST DESIGN GUIDELINES 3.6.2.1 DESIGN CODES:

The following codes and reports are permitted to be used in pre cast design:

3.6.2.2

3.6.2.3

3.6.2.4

1.

BS 8110-1997

2.

ACI 318 – latest edition

3.

PCI Design handbook fifth edition.

4.

CPCI design manual 4.

5.

UBC 1997 and ASCE 7-7 (Seismic loads).

6.

ASCE 7 – latest edition (Wind loads).

7.

IBC-latest edition (International Building Code) Durability: Material strength of factory produced pre cast reinforcedand pre-tensioned concrete components shall comply with design performance of the structure during its life span. Concrete cover, fire resistance, crack and deflection control and resistant to chloride ion attack should be maintained within the relevant codes limitations. Concrete strength: The 28-day design strength of concrete used in pre cast and pre stressed products shall be 40 MPa minimum. The transfer strength (when the pre stress force is transferred to the concrete) can be 25 MPa or as required by the design.

1.

Hollow core floor slabs: 30 to 40

2.

Double tee floor slabs: 25 to 35 Beams: 10 to 20

STORAGE, TRANSPORTATION, HANDLING AND ERECTION

Pre cast units shall be designed to resist all kinds of stresses induced by storage, handling, transport and erection, without permanent deformation and shall be braced for handling and transportation when necessary, Figs (3.14 a - f).

94

Fig. (3.14a) Supplemental Lifting Points

Crane Line Load = W T = Sling Load =

WF 2

Sling Angle =

Total Load = w

Span to depth ratio: as a guidance for span to depth ratios of flexural elements, the following figures could be adopted:

3. 3.6.2.5

Supplemental line with “ Come-Along”

Multiplication Factor “F” for the Total Load on Sling With a Sling Angle of

F

a

90

75

60

45

30

1.00

1.04

1.16

1.41

2.00

NOTE: is usually not less than 60 check bl-directional sling angle. a A 30 sling angle is not recommended.

Fig. (3.14b) Force in Lift Lines

95

SECTION: 3

SECTION: 3


T =

P


P sin0 cos

Y 0 yc

P tan0

PH =

Z c.g.

P

T

T

P

Y

(a) Four Points With Two Cranes PV

PV e

yt yc X

yb

c.g. M x= P H yc M x=

P yc tan0

M z = P ve M z=

Pe tan0

(b) Eight Points with two Cranes and Two Spreader Beams

Fig. (3.14c) Moment caused by eccentric lifting Fig. (3.14e) Hook lifting

Spreader Beam

Equal

c.g.

Rolling Block

Force Equal on All Lines

Equal

a) Four poi nts with Spreader Beam

b) Eight Poi nt swith Spreader Beam

All Reactions Equal

R

R

R

R

Fig. (3.14f) Use of spreader beam

Fig. (3.14d) Arrangement for equalizing lifting loads

96

97

SECTION: 3


1.

SECTION: 3


Each element must be stable after erection and offer resistance to wind, accidental impact, and loads that may be imposed due to other construction operations, Fig (3.15).

Panel Loading

Gravity Loading

Fig. (3.16a) Transporting single-story panels

Seismic Loading Parallel to Panel Face

Seismic or Wind Loading Perpendicular to Panel Face

Fig. (3.16b) Transporting of long panels Fig. (3.15) Example of Precast panel with Earthquake loading (1-x)

2.

3.

4. 5.

98

Surfaces shall intend to remain free of discernible cracks by limiting the flexural tension to the modulus of rupture modified by a suitable safety factor. The arrangement of temporary bracing should not interfere with adjacent erection and other construction processes. Bracing must be maintained until permanent connections are completed. Please refer to BS8110-1997 section 6.2.11 and PCI Section: 5.2.4.2. The method used for transporting pre cast concrete products shall be considered in the structural design including size and weight limitations and the dynamic effects imposed by road conditions, Figs. (3.16 a,b & c).

x

x

x

M1

M1

M2

M2 (a) One End Cantllevered x= 1 1+ 2

yb yt

1+

yb yt

Where: yb = distance from the bending axis to the bottom fiber yt = distance from the bending axis to the top fiber

(b) Both End Cantllevered x=

1 2 1+ 1+

yt yb

Fig. (3.16c) Equations for Equal Tensile Stresses at top and bottom of member

99

SECTION: 3

SECTION: 3



3.6.2.6 CONNECTIONS

Typical connections details shown in Figs (3.17 a - f) shall be followed. 1.

The connection must have adequate strength to transfer the forces to which it will be subjected during its lifetime.

Design Considerations: With large factors of safety, friction may transfer nominal forces Additional structural integrity ties may be required

2.

The connection must have ability to undergo relatively large inelastic deformations without failure.

3.

The stresses caused by restraint of creep, shrinkage and temperature change (Volume change) must be considered in the design.

Fabrication Considerations:

The connection must meet the durability and fire resistance requirements.

Erection Considerations:

4. 5.

Topping if required

Clean and simple Bearing strip

Clean and simple

P.C. or C.I.P. concrete beam

Connections shall be checked for the expected earthquake and wind forces.

Design Considerations:

Can be designed as structural integrity tie

Fig. 5.3.3

with beaded stud anchors

Can transfer internal diaphragm forces

With returns Topping if required

Plate with deformed bar grouted in slab keyway

Fabrication Considerations: Advantageous to have no hardware in slab


Beam embedments must line up with slab joints Bearing strip

Accommodates variations in slab length Erection Considerations: Advantageous to have connection completed by follow-up crew


Difficult for welder to hold loose plate in position

Reinforcement draped over beam and grouted in slab keyway

Can transfer internal diaphragm forces Can be designed as structural integrity tie Consider concrete cover on reinforcement over beam

Grout


Fig. 5.3.1

Slab layout must have opposing joints lined up Bearing strip

Grout Reinforcement grouted in slab keyway

Design Considerations: Can transfer internal diaphragm forces Can be designed as structural integrity tie

Grout

Erection Considerations: Topping if required


Clean and simple


May increase beam reinforcement for shallower beam Layout must have opposing slab joints lined up

Erection Considerations: Clean and simple

Topping if required

Fig. 5.3.4

Bearing strip P.C. or C.I.P. concrete beam Fig. 5.3.2

Fig. (3.17a) Connections

100

Fig. (3.17b) Connections

101

SECTION: 3

SECTION: 3



Reinforcement grouted in slab keyway


Design Considerations: Can transfer internal diaphragm forces Will develop volume change restraint forces that must be considered in design of connections

Topping if required


Can transfer internal diaphragm forces Can be designed as structural integrity tie Horizontal shear in composite beam must be transfered

Reinforcement per design Topping

Opposing slab joints must line up

FabricationConsiderations:

Slab manufacturing system must allow bottom weld anchors

Clean and simple for slabs

Beam inserts must align with slab inserts allowing fabrication tolerances

Weld Plate (alt. ends) Bearing strip




Connections can be completed by follow-up crew Access for welding may require ladders or scaffold


Dam cores

Bearing strip

Beam may have to be shored until topping is cured Horizontal shear reinforcement may present safety hazard for erector Core dams must be placed


Spacer may be required to make weld Fig. 5.3.7 Fig. 5.3.5 Beam and slab inserts must align

Design Considerations: Can transfer internal diaphragm forces Can be designed as structural integrity tie Horizontal shear from beam cap must be transferred Opposing slab joints must line up

Reinforcement per design Topping if required

Concrete

Can transfer diaphragm shear Can provide lateral brace for beam Potential for negative moment in slabs

with beaded stud anchors or deformed bar Topping if required

FabricationConsiderations: Slab insert difficult to install. Because of tolerance on sawcut ends, the insert should be installed after slabs are cut to length Beam and slab inserts must align

Fabrication Considerations: Clean and simple for slabs


Dam cores


Bearing strip

Bearing strip


Beam may have to be shored until cap is cured Horizontal shear reinforcement may present safety hazard for erector Core dams must be placed

If required for lateral beam stability, welding may have to be completed as slabs are set


P.C. or C.I.P. concrete beam Fig.

Fig. (3.17c) Connections

102

Plate as required by design



5.3.6

Fig. 5.3.8

Fig. (3.17d) Connections

103

SECTION: 3

SECTION: 3



Reinforcement grouted in slab keyway Topping if required

DesignConsiderations:


Plate with deformed bar anchor grouted in slab keyway

Can transfer diaphragm shear Can provide lateral brace for beam

Can transfar diaphragm shear Can be designed as structural inegrity tie Topping if required

Potential to develop negative moment in slabs


Longitudinal bar as req'd.

FabricationConsiderations: Clean and simple for both beam and slabs Dowels from beam may present safety hazard


Plates in beam must align with slab joints allowing tolerance

Reinforcement must be tied in place Concrete must be cast around reinforcement Edge form is required for cast-in-place concrete Bearing strip

Plate with beaded stud anchors


Dowels from beam may present safety hazard

Bearing strip P.C. or C.I.P. concrete beam Fig. 5.3.11

Connection can be completed with a follow-up crew Lateral bracing for beam will not be provided until keyway grout cures


Weld Plate (alt. ends)

DesignConsiderations:

Topping if required

Can transfer internal diaphragm forces Will develop volume change restraint forces that must be considered in design of connection

Fig. 5.3.9



Slab manufacturing system must allow bottom weld inserts Beam and slab inserts must align with allowance for tolerance


Can transfer internal diaphragm forces Can be designed as structural integrity tie

Topping if required


Bearing strip

Erection Considerations: Connections can be completed by follow-up crew Access for welding may require ladders or scaffold Spacer may be required to make weld

with beaded stud anchor

P.C. or C.I.P. concrete beam Fig. 5.3.12

Clean and simple

Fig. (3.17f) Connections Erection Considerations:

Bearing strip

Clean and simple

DesignConsiderations: Weld plate

Can transfer diaphragm shear Tortional and lateral beam restraint can be provided

Keyway dimensions may limit the reinforcement diameter P.C. or C.I.P. concrete beam

Will develop volume change restraint forces that must be considered in design of connection

FabricationConsiderations: Fig. 5.3.10

Topping if required Bearing strip

Slab manufacturing system must allow bottom weld inserts Beam and slab weld anchors must align with allowances for tolerance

Erection Considerations: Connections can be completed by follow-up crew


with headed stud anchors

Access for welding may require ladders or scaffold Spacer may be required to make weld

Fig. (3.17e) Connections

104

Fig. 5.3.13

Fig. (3.17g) Connections

105

SECTION: 3


3.6.2.7 General considerations

3.6.3

106

1.

Structural shall be designed for vibration as PCI S: 9.7.

2.

Minimum total bearing width shall be 100 mm; the design of bearing shall be as per Section: 5.2.3 in BS8110.

3.

The pre cast design shall be complied with section 5 in BS 8110.

4.

The pre cast system for slabs shall be with toping co nc re te inclusive minimum reinforcement mesh of T8200mm.

DOCUMENTS REQUIRED REQUIRED FOR OBTAINING PRECAST STRUCTURE PERMIT 1.

Consultant cover letter indicating the submission subject and description of submission purpose , project ID, specialist and system IDs, details of attached documents, etc

2.

Specialist document: prequalification-trading license- system approval, designer approval, site engineer, etc…

3.

Undertaking letter from specialist for pre stressing work (design and execution) approved by the consultant.

4.

Design criteria explaining all design data.

5.

Software license copy.

6.

PDF detailed drawings signed and stamped by specialist and consultant. DWG drawings are required for review purposes.

7.

List of submitted drawings.

8.

PDF calculation signed and stamped by specialist and consultant, including gravity, lateral force and thermal calculations (If any).

9.

3D models of the full structure to check the lateral force effects on P.T slabs design.

10.

P.T software models.

11.

Latest approved structural drawings.

12.

Third party report (If applicable).

107


108

04 SECTION

109

N O I T C E S

4


SECTION:4


4.2.2

4.1

INTRODUCTION The guidelines in this section are applicable for steel structure and are intended to provide minimum structural design requirements for steel buildings and other structures fabricated and erected with structural steel. The guidelines are intended to give a general idea of the basic requirements for steel structures while designing structures within the CED Trakhees jurisdiction. Engineers shall refer to the applicable codes for the detailed technical guidance and requirements. It is anticipated that the use of these guidelines will result in a uniform design and construction of buildings throughout projects in CEDTrakhees jurisdiction.

SEISMIC LOADS 1.

UBC 1997, Volume 2, ‘Structural Engineering Design Provisions’, Division IV ‘Earthquake Design’

2.

Zone 2A shall be adopted for all structures.

3.

For special steel structures and tall buildings, relevant sections of structural design guidelines for building structures are applicable.

4.2.3 WIND LOAD

Any requests for variations to the guidelines presented must be fully documented and presented to the CED-Trakhees for review and acceptance prior to any work commencement. The design shall meet all relevant standards for safety, durability, fire resistance and serviceability. The designer shall investigate alternative systems and shall achieve optimized economical and constructible solution.

1.

ASCE 7: ‘Minimum Design Loads for Buildings and Other Structures’ - Chapter 6. Design shall be based on basic wind velocity of 45 m/s.

2.

For all structures where wind loads are applied as per codes, other directions than the two orthogonal ones to be investigated for ultimate and serviceability limit states. The same shall be carefully studied for irregular buildings.

3.

For special steel structures and tall buildings, relevant sections of structural design guidelines for building structures are applicable.

Sections in design guidelines for building structures shall be referred to where indicated.

4.2

4.2.4 DESIGN CODES

APPLICABLE CODES The following codes are permitted for design of steel structures. Design codes not listed in this document shall be submitted for review and approval prior to adopting in the design. Consultant should ensure that selected design standards are the latest editions and fully compatible with CED’s design regulations & guidelines.

4.2.1

110

1.

BS 5950: ‘Structural Use of Steelwork in Buildings’.

2.

AISC 360: Specification for Structural Steel Buildings

3.

UBC 1997, Volume 2, ‘Structural Engineering Design Provisions’.

4.

IBC ‘International Building Code’, excluding seismic design provisions.

5.

For codes on concrete and other elements used in steel buildings, refer to codes listed in structural design guidelines for building structures.

DEAD AND LIVE LOADS 1.

BS 6399: Part 1 ‘Loading For Buildings: Code of Practice for Dead and Imposed Loads’.

2.

BS 6399: Part 3 ‘Loading For Buildings: Code of Practice for Imposed Roof Loads’

3.

ASCE 7: ‘Minimum Design Loads for Buildings and Other Structures’, Chapter 3 ‘Dead Loads’ and Chapter 4 ‘Live Loads’

4.

Adopted dead and live loads shall satisfy recommendations of the Dubai Municipality, CED - TRAKHEES and other relevant statutory authorities.

4.3

PERFORMANCE CRITERIA - ANALYSIS, DESIGN AND DETAILING The following sections present the analysis, design and detailing criteria with particular reference to normal and low to medium rise steel buildings and structures. For special steel structures and tall steel buildings, detailed performance criteria given in guidelines for building structures shall be referred to and the relevant sections shall be considered in the design.

111

SECTION:4


4.3.1


10.

GENERAL 1.

Minimum design life of the steel structure shall be 50 years unless otherwise specified.

2.

The aim of structural design should be to provide, with due regard to economy, a structure capable of fulfilling its intended function and sustaining the specified loads for its intended life.

3.

4.

112

SECTION:4

4.3.2 LOADING All relevant loads should be considered separately and in such realistic combinations as to comprise the most critical effects on the elements and the structure as a whole.

The design should facilitate safe fabrication, transport, handling and erection. It should also take account of the needs of future maintenance, final demolition, recycling and reuse of materials. The structure should be designed to behave as a one threedimensional entity. The layout of its constituent parts, such as foundations, steelwork, joints and other structural components should constitute a robust and stable structure under normal loading to ensure that, in the event of misuse or accident, damage will not be disproportionate to the cause.

5.

The basic anatomy of the structure by which the loads are transmitted to the foundations should be clearly defined.

6.

Any features of the structure that have a critical influence on its overall stability should be identified and taken account of in the design.

7.

Each part of the structure should be sufficiently robust and insensitive to the effects of minor incidental loads applied during service that the safety of other parts is not prejudiced.

8.

The design intention should be to adopt a layout so as to rationalize the use of member sizes and details to achieve maximum structural efficiency and to obtain a combination of materials and workmanship consistent with the overall requirements of the structure.

9.

Design shall include all limit states in addition to the limit states of strength and serviceability as follows: a.

Strength limit states including general yielding, rupture, yielding, buckling and transformation into a mechanism.

b.

Serviceability limit states

c.

Stability against overturning & sway.

d.

Fracture due to fatigue and brittle fracture.

e.

Corrosion and durability.

Details of members and connections should be such as to realize the assumption made in design with out affecting any other part of structure.

4.3.3

1.

Dynamic loads shall be considered for cranes and for members supporting machineries as per the manufacturer’s recommendations and as per the applicable codes.

2.

Temperature effects shall be included in the design of the structure including temperature effects during erection stage, operational aspect, etc.

LIMIT STATE OF STRENGTH In checking the strength and stability of the structure all loads shall be multiplied by the applicable load factors and all combinations of loads producing the worst effects on the structure and its constituent elements shall be identified and used in the strength limit state design. Load factors and combinations given in Table 1 below shall be used when BS 5950 is adopted for design. 1.

Factors and combinations shall be used consistently throughout the project as per the design code adopted. Mixing factors and combinations from different codes are not allowed.

113

SECTION:4

SECTION:4


Loading

Factor, f

Dead load Dead load restraining uplift or overturning

1.4 1.0

Dead load acting with wind and imposed loads combined

1.2


a) Vertical deflection of beame due to imposed load Cantilevers

Length/180

Beams carrying plaster or other brittle finish

Span/360

Other beams (except) purlins and sheeting rails

Span/200

Purlins and sheeting rails

See 4.12.2

b) Horizontal deflection of columns due to imposed load and wind load

Imposed load Imposed load acting with wind load

1.6 1.2

Tops of coloumnsin single-storeybuilding, exceptportal frames

Height/300

Coloumnsinportalframe buildings,notsupportingcranerunways

To suit cladding

Wind load

1.4

Coloumns supporting crane runways

To suit crane runway

In each storey of a builidng with more thean one storey

Height of that storey/300

Wind load acting with imposed load or crane load Forces due to temperature effects

1.2

c) Crane girders

1.2

Vertical deflection due to static vertical wheel loads from overhead travelling cranes Horizontal deflection (calculated on the top flange properties alone) due to horizontal crane loads

Crane loading effects Vertical load Vertical load acting with horizonal loads (crabbing or surge)

1.6

Horizontal load

1.6

Horizontal load acting with vertical

1.4

Crane load acting with wind load*

1.2

Table 4.2. Deflection Limitations - BS 5950 3.

When checking for deflections the most adverse realistic combination and arrangement of serviceability loads shall be considered, and the structure may be assumed to behave elastically. On low pitched and flat roofs the possibility of ponding should be investigated.

4.

Vertical and horizontal limits of deflection due to all loads shall in general be limited to the deflection l imits specified in the codes. Special care shall be taken to limit the deflection to suit the cladding, crane girder tolerances, members supporting sensitive machineries etc.

5.

Vibration and oscillation of building structures should be limited to avoid discomfort to users and damage to contents. Reference to specialist literature shall be made as appropriate.

6.

In order to ensure the durability of the structure under conditions relevant both to its intended use and to its intended life, the f ollowing factors should be taken into account in design:

Table 4.1. Load Factors and Combinations - BS 5950

4.3.4 LIMIT STATE OF SERVICEABILITY Serviceability loads shall be taken as the unfactored loads with all serviceability load combinations specified in the relevant codes used.

2.

114

Span/500

1.4

* When considering wind or imposed load and crane loading acting together the value of f for dead load may be taken as 1.2.

1.

Span/600

Deflections of a building or part under serviceability loads should not impair the strength or efficiency of the structure or its components, nor cause damage to the finishing. Deflection limits shall not exceed the suggested values given in Table 2. as per BS 5950.

•

Environment around the structure and the degree of ex posure.

•

Shape of the members and structural detailing.

•

Protective measures.

115

SECTION:4


•

Whether inspection and maintenance are possible.

•

As an alternative to the use of protective coatings, weather resistant steels to BS EN 10155 may be used. Steels complying with other prominent international codes such as the American and European codes are acceptable subject to review and approval by the authority.

SECTION:4


4.

Where aerodynamic instability can occur, account should be taken of wind induced oscillations.

5.

Where fatigue is critical, all design details should be precisely defined and the required quality of workmanship should be clearly specified.

6.

Resistance to fatigue should be determined by reference to BS 7608 or applicable codes.

4.3.5 FOUNDATION Foundations shall accommodate all forces imposed on them. Attention should be given to the method of connecting the steel superstructure to the foundations and to the anchoring of holding-down bolts. 1.

Where it is necessary to quote the foundation reactions, it should be clearly stated whether the forces and moments result are from factored or unfactored loads. Where they result from factored loads, the relevant factors for each load in each combination should be stated.

4.3.8 STRUCTURAL INTEGRITY All buildings shall be effectively tied together at each principal floor level. 1.

Each column shall be effectively held in position by means of horizontal ties in two directions, approximately at right angles, at each principal floor level supported by that column.

2.

Horizontal ties shall be provided at roof level, except where the steelwork only supports cladding that weighs not more than 0.7 kN/m2 and that carries only imposed roof loads and wind loads.

3.

Continuous lines of ties should be arranged as close as practicable to the edges of the floor or roof and to each column line. Ties designed and provided as shown in Figures (4.1) and (4.2) are acceptable.

4.3.6 HOLDING DOWN BOLTS Holding down bolts should be designed to resist tension due to uplift forces and tension due to bending moments as appropriate. 1.

Holding-down bolts required to resist tension should be anchored by a washer plate or other load distributing member embedded in the foundation. This plate or member should be designed to span any grout tube or adjustment tube provided for the holdingdown bolt.

2.

Alternatively, a bend or hook in accordance with the minimum bend radius recommended in the codes may be used.

3.

Expanding anchors or resin-grouted anchors are generally not recommended. If they are required in exceptional cases, it should be demonstrated that the required capacity can reliably be achieved, both by the anchor and by the foundation.

Column ties Edge ties

Re-entrant corner Tie anchoring re-entrant corner Edge ties

A

4.3.7 FATIGUE

116

1.

Fatigue need not be considered unless a structure or element is subjected to numerous significant fluctuations of stress.

2.

Stress changes due to normal fluctuations in wind loading need not be considered.

3.

Structural members that support heavy vibrating machinery or plant should be checked for fatigue resistance.

Tie anchoring column A

Edge ties

Beams not used as ties

Fig (4.1) Tying of Columns – Beams connecting columns only and at reentrant corners used as Ties

117

SECTION:4

SECTION:4



4.4

GENERAL GUIDELINES FOR INDUSTRIAL STEEL STRUCTURES

All beams designed to act as ties ROOF PURLIN EAVE STRUT RIGID FRAME COLUMN

RIDGE ROOF SYSTEM

Tie anchoring column A

RIGID FRAME

GUTTER

T H G I E H E V A E

A

N P A R S E A C L

CMU WALL GIRT BRACING

Fig (4.2) Tying of Columns – All beams including secondary beams used as Ties

118

All horizontal ties, and all other horizontal members, should be capable of resisting a factored tensile load, which should not be considered as additive to other loads, of not less than 75 kN.

5.

Each portion of a building between expansion joints shall be treated as a separate building.

6.

For special buildings where it is stipulated to be designed to avoid disproportionate collapse, all requirements with regard to tying of columns, continuity of columns, resistance to horizontal forces, notional removal of column, accidental loading and key element design etc. shall be carefully studied and designed as required by the relevant sections of codes.

ENDWALL FRAME ENDWALL COLUMN

ENDWALLRAFTER SIDEWALL

4.

B A Y S P A C I N G

ENDWALL ENDWALL CORNER COLUMN

Fig (4.3). Parts of a Typical Steel Industrial Building 1.

Design calculations and details of all parts (See Figure (4.3)) of a steel industrial building including foundations shall be submitted.

2.

Footings shall be designed to solely resist the horizontal thrust from the portal frames. Hair pin bars connecting pedestal to the grade slab for horizontal restraint shall be avoided.

3.

A minimum footing effective depth of 300mm for all footings with reinforcement cover meeting the durability requirements and the recommendations in the soil investigation report shall be provided.

4.

Connections and loading drawings shall be provided with the input and output from the applicable steel design software.

5.

All steelwork drawings shall be properly coordinated with the architectural and services drawings. Bracings shall not foul with openings & windows. A minimum of two bays shall be braced.

6.

For built up sections, thickness of structural steel members shall not be less than 6mm for main members and 4mm for secondary members.

7.

Anti-sag rods shall be a minimum of 16mm diameter and the maximum spacing of rods shall not exceed 3.8m. The roof bracing rods used shall be of 20mm minimum diameter.

119

SECTION:4


8.

Wall wind bracing members shall be rolled steel sections such as angles or pipes. Rods or cables shall not be used as wall wind bracing elements.

Wall Bracings – Angle, Pipes or Suit able steel sections only. Rods or cables shall not be used

Fig (4.4). Wall Bracing

120

9.

An elevation view showing the load transmission from the wind bracing to the ground shall be submitted.

10.

All flange braces for rigid column frames shall be fixed to side wall girts before constructing the exterior block work.

11.

Bracing shall not be removed and shall remain intact through out the life of the building.

12.

Crane supplier’s data sheets shall be provided for crane design and drawings.

13.

Protective coating to structural steel shall be done at workshop and the required thickness shall be 240-270 microns.

14.

In cases where the foundations are designed by the main consultant and steel superstructure is designed by steel specialist contractors, the consultant’s submission shall include design and details of Anchor bolts with the bolt grade, diameter and the length along with the foundation design and details.

15.

All steel member bolted connections in the drawing shall show the bolt grade, diameter and length. All Bolt length shall be checked for end plate thickness, washer, nuts, threading projection beyond nut etc.

16.

Welded connection details shall include the type of welds, thickness, length etc. indicated by the standard welding symbols.

SECTION:4


17.

All internal partitions shall be designed for internal critical wind pressures coefficients.

18.

Drawings shall include cross sections for the steel column fixing to the pedestal.

19.

Pedestal sizes shall include provision for RCC columns/wall stiffeners if present, base plate size with clearance (to avoid overlapping of reinforcement and anchor bolts details etc) and grouting details.

20.

Roof gutters shall be properly designed and detailed and the necessary calculations shall be submitted.

21.

All foundation levels in CED-JAFZA/DM datum shall be mentioned clearly in the drawing as per soil report recommendations.

22.

Maximum distance between the bolts in any connection shall be limited to 350mm or shall be provided with stiffener plates.

23.

Loading diagram for all floors and roofs including dead, imposed, collateral, crane loads etc. shall be provided.

24.

Composite deck slab details shall include concrete thickness and grade, reinforcement, sheet profile and sheet design data from the profile manufacturer.

25.

Purlin detail shall include data sheets with properties and design data from the purlin manufacturer.

26.

All joint details and layout of joints for expansions and contraction joints, control joints, construction joints etc. shall be provided.

27.

General structural steel notes showing the grades of steel and material properties, codes adopted in design, loadings considered, typical details, fabrication, erection tolerances, painting and all other required specifications for the project shall be provided.

28.

Drawings shall contain end gable view of the steel structural frames.

29.

All internal columns shall be protected with encasement or protection bollard to avoid accidental damage to the structure.

30.

Soakpits (if required) shall be located away from the main structures and foundations such that the soil strata below the foundations are not disturbed at any stage during or after construction.

121

SECTION:4


SECTION:4


REFERENCES

122

123

REFERENCES

124

REFERENCES

1.

Anandarajah, K. S. and Kuganenthira, N. “Incremental Stress-Strain Behaviour of Granular Soil”, J. Geotech. Eng. Div. ASCE, Vol. 121, No. 1, 1995, pp. 57 - 68.

22.

Harr , M. E. “ Foundations of Theoretical Soil Mechanics”, McGraw-Hill Book Company, New York.

2.

Bowles J.E. “Foundation Analysis and Design”5th Edition-Mc Graw Hill International Edition, 1997.

23.

3.

Bowles J.E. “Physical and Geotechnical Properties of Soils”5th Edition-Mc Graw Hill International Edition.

Holeyman, A. E. (1997). “An Earthquake Engineering Approach to Vibrocompaction ”, Proceedings of the 14th International Conference on Soil Mechanics and Foundation Engineering.

24.

4.

BS 410: 1986 “Specifications for Test sieves”.

Kramer, S. L. (1996). “Geotechnical Earthquake Engineering”, Prentice-Hall, Inc., Upper Saddle River, New Jersey.

5.

BS1377: 1990 “Soils for civil engineering purposes”.

25.

Hsai Yang Fang “Foundation Engineering Handbook” Second Edition, Van Nostrand Reinhold.

6.

BS 5930: 1999 “Code of practice for site investigation”.

26.

7.

BS 6031:1981 “Code of Practice for Earthworks”.

Hunt, R. E. “Geotechnical Engineering Analysis and Evaluation” McGraw-Hill, New york .

8.

BS 8002: 1994 “Code of practice for Earth retaining structures”.

27.

Meyerhof, G. G. “Shallow Foundations”, J. Soil Mech. and Foundation Div. ASCE, Vol. 91, No. SM2, 1965, pp. 2-31.

28.

Michalowski, R. L. and Shi, L. “Bearing Capacity of Footing Over Two-layer Foundation Soils”, J. Geotech. Eng. Div. ASCE, Vol. 121, No. 5, 1995, pp. 421 - 428.

29.

Mslivec, A. and Kysela , Z. “The Bearing Capacity of Building Foundations” Elsevier Scientific Publishing Company, Oxford, 1978.

30.

Seed, H. B. and Idriss, I. M. (1971). “Simplified Procedure for Evaluating Soil Liquefaction Potential”, Journal of Soil Mechanics & Foundations Division, ASCE, 97(SM9), 1249-1273.

31.

Terzaghi , K., Peck R. B. and Mesri, G. “ Soil Mechanics in Engineering Practice” , John Wiley & Sons Inc., Third Edition, 1996.

32.

Tomlinson M.J. “Foundation Design and Construction” Fifth Edition – Lomgman Scientific & Technical.

33.

Tomlinson M.J. “Pile Design and Construction Practice” Fourth Edition.

34.

Youd, T. L., Idriss, I. M., Andrus, R. D., Arango, I., Castro, G., Christian, J. T., Dobry, R., Finn, W. D. L., Harder, L. F., Hynes, M. E., Ishihara, K., Koester, J. P., Liao, S. S. C., Marcuson, W. F., Martin, G. R., Mitchell, J. K., Moriwaki, Y., Power, M. S., Robertson, P. K.,Seed, R. B., and Stokoe, K. H. (2001). “Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998 NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils”, Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 127(10), 817-833.

35.

Unpublished reports of various projects under the umbrella of Trakhees Authority Jurisdiction.

9.

BS 8004: 1986 “Code of practice for foundations”.

10.

BS 8081: 1989 “Code of practice for Ground anchorages”.

11.

BRE SP1:2005 “Concrete in aggressive ground”.

12.

British Geological Survey “Geology and Geophysics of United Arab Emirates”, Vol.2. Geology”. (2006).

13.

British Geological Survey “Geology and Geophysics of United Arab Emirates”, Vol.4. Geological Hazards. (2006).

14.

CIRIA Publication-31 “Guide to Concrete Construction in the Gulf Region”.

15.

CIRIA Publication-181 “Piled Foundation in weak rock”.

16.

Das, B. M. (1994). “Principles of Geotechnical Engineering”, 3rd edition, PWS Publishing, Co., Boston, Massachusetts.

17.

Dubai Municipality “Dubai Tide Tables”. (2008).

18.

Duncan C. Willry “Foundation on Rock”, 2nd edition, E & FN Spon, New York, (1999).

19.

Florkiewicz, A. “Upper Bound to Bearing Capacity of Layered Soils”, Can. Geotechnique J. Vol. 26, No. 4, 1989, pp. 730 - 736.

20.

Georgiadis, M. and Michalopoulos, P. A. “Bearing Capacity of Gravity Bases on Layered Soils”, J. Geotech. Eng. Div. ASCE, Vol. 111, No. 6, 1984, pp. 712 - 729.

21.

Griffiths, D. V. “Computation of Bearing Capacity on Layered Soils”, Proc., 4th int. Conf. Numerical. Methods Geomech. , Z. Eisenstein. Ed. Balkema, Rotterdam. the Netherlands., 1982, pp. 163 -170 .

125

FIGURES & TABLES

126

INDEX

127

INDEX

INDEX

Figure No.

Figure Title

Figure 1.1:

Boreholes Distribution

Figure 1.2:

Procedures for Standard Penetration Test (SPT)

Figure 1.3:

Figure No.

Figure Title

13

Figure 1.29:

Cement Grouting (Slurry Grouting) Technique

45

15

Figure 1.30:

Compaction Grouting Technique

45

Rock Core

16

Figure 1.31:

Jet Grouting Technique

46

Figure 1.4:

Pressure Meter / Dilatometer Test

17

Figure 1.32:

Cone Penetration Test (CPT) Readings

48

Figure 1.5:

Earth Profile

24

Figure 1.33.a:

Contiguous Piles Shoring System

51

Figure 1.6:

Describing Soil Properties

24

Figure 1.33.b:

Secant Piles Shoring System

51

Figure 1.7:

Standard Down Hole Seismic

26

Figure 1.33.c:

Soldier Piles Shoring System

52

Figure 1.8:

Safe angel for open excavation

27

Figure 1.34:

Shoring Stages of Construction

52

Figure 1.9:

Shoring Systems

28

Figure 1.35:

Tie Back Anchors Method Statement

54

Figure 1.10:

Surface Dewatering System (French Drains)

29

Figure 1.36:

Tie Back Anchors Stressing Testing

55

Figure 1.11:

Well Point Dewatering System

30

Figure 1.37:

Method Statement for Different Types of Bored Piles

58

Figure 1.12:

Deep Wells Dewatering System

31

Figure 1.38:

Method Statement for Drilled Bored Piles

59

Figure 1.13:

Well Pit Details (Running / Finished)

32

Figure 3.1:

Pre stress bonded system

80

Figure 1.14:

Details of Dewatering Deep Well

33

Figure 3.2:

Anchorage system

81

Figure 1.15:

Piles Distribution

35

Figure 3.3:

Pre stress equipment

82

Figure 1.16:

Wick Drains Technique

36

Figure 3.4:

Pre stress strands

82

Figure 1.17:

Method statement of Dynamic Compaction

37

Figure 3.5:

Ducts

83

Figure 1.18:

Comparison between Dynamic & Vibro Compaction

37

Figure 3-6:

Ducts Chairs

83

Figure 1.19:

Range of Soils Suitable for Vibratory Techniques

38

Figure 3.7:

Shear stud

83

Figure 1.20:

The Most Suitable Improvement Technique for both

Figure 3.8:

Slab thickness

87

Figure 3.9:

Bonded-distributed systems

88

Figure 3.10:

Factor taking account of long term effects

89

Cohesive and Granular Soils Figure 1.21:

128

Page No.

39

Cost Comparison for the Different Improvement

Page No.

Techniques for Granular Soils

39

Figure 3.11:

U-Bar at the edge of slab and junction of wall and slab

90

Figure 1.22:

Deep Compaction (Vibro Compaction) Technique

40

Figure 3.12:

Anti Burst steel at dead and live ends

90

Figure 1.23:

Deep Compaction (Vibro Compaction)

Figure 3.13:

Common Precast Concrete products

93

Method Statement

41

Figure 3.14.a:

Supplemental Lifting Points

95

Figure 1.24:

Dynamic Compaction Technique

41

Figure 3.14.b:

Force in Lift Lines

95

Figure 1.25:

Vibro-replacement Stone Columns Technique

42

Figure 3.14.c:

Moment caused by eccentric lifting

96

Figure 1.26:

Deep Mixing (Soil Mixing) Technique

43

Figure 3.14.d:

arrangement for equalizing lifting loads

96

Figure 1.27:

Different Procedures of Grouting Techniques

44

Figure 3.14.e:

Hook lifting

97

Figure 1.28:

Permeation Grouting Technique

44

129

INDEX

Figure No.

Figure Title

Figure 3.14.f:

Use of spreader beam

97

Figure 3.15:

Example of Precast panel with Earthquake loading

98

Figure 3.16.a:

Transporting single-story panels

99

Figure 3.16.b:

Transporting of long panels

99

Figure 3.16.c:

Equations for Equal Tensile Stresses at top and bottom of member

99 100

Figure 3.17.a:

Connections

Figure 3.17.b:

Connections

101

Figure 3.17.c:

Connections

102

Figure 3.17.d:

Connections

103

Figure 3.17.e:

Connections

104

Figure 3.17.f:

Connections

105

Figure 3.17.g:

Connections

105

Figure 4.1:

Tying of columns-beam connecting columns only

Figure 4.2:

Tying of columns-All beams including secondary

Figure 4.3:

Parts of Typical Steel industrial Building

119

Figure 4.4:

Wall Bracing

120

Table No.

Table Title

Table 1.1:

Correlation between SPT Blows & Sand Relative Density

16

Table 1.2:

Soil Classification System

18

Table 1.3:

Soil Properties Correlations

18

Table 1.4:

Rock Fracture State

19

Table 1.5:

Rock Strength Classification

19

Table 1.6:

Sandstone / Conglomerate Properties

19

Table 1.7:

Elastic Parameters for Various Soils

19

Table 1.8:

Carbonate Classification System

22

Table 1.9:

UBC 1997 Soil Profile Class Estimation

26

Table 4.1:

Load Factors and Combinations - BS5950

114

Table 4.2:

Deflection limitation BS5950

115

and at reentrant corners used as Ties beams used as Ties

130

Page No.

117 118

Page No.

Building Regulations & Design Guidelines- Structural

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