STRUCTURAL ANALYSIS AND DESIGN REPORT FOR Residential Building of
NIR KUMARI RAI
PREPARED BY: Enginagar Construction Pvt. Ltd.
July 14, 2017
TABLE OF CONTENTS 1.
INTRODUCTION .............................................................................................................................. 3 1.1 1.2 1.3
2.
DETAILED PARAMETERS OF THE BUILDING ...................................................................................... 4 2.1 2.2 2.3 2.4 2.5
3.
DESIGN OF COLUMNS AND BEAMS .......................................................................................................20
DESIGN SUMMARY ....................................................................................................................... 38 8.1 8.2 8.3 8.4 8.5
9.
SUPPORT REACTIONS ..........................................................................................................................14 BENDING MOMENT AND SHEAR FORCE DIAGRAMS ................................................................................. 15 MODEL TIME PERIODS AND AUTO SEISMIC LOADS TO HORIZONTAL DIAPHRAGMS ............................................ 19
DESIGN OF THE STRUCTURE ....................................................................................................... ....20 7.1
8.
GRIDS AND NODE NUMBERS ............................................................................................................. 10 COLUMNS AND BEAMS SECTIONS ....................................................................................................... 11 LOADING ON THE STRUCTURE ............................................................................................................. 12
ANALYSIS OF THE STRUCTURE ..................................................................................................... ....14 6.1 6.2 6.3
7.
LIMIT STATE METHOD ........................................................................................................................ 8
MODELLING OF THE STRUCTURE ..................................................................................................... 9 5.1 5.2 5.3
6.
DEAD LOADS (DL) ............................................................................................................................. 6 LIVE LOADS (LL) ............................................................................................................................... 6 EARTHQUAKE LOADS (EL) ................................................................................................................... 6 LOAD COMBINATIONS ........................................................................................................................ 7
DESIGN CRITERIA ............................................................................................................................ 8 4.1
5.
GENERAL PARAMETERS ...................................................................................................................... 4 STRUCTURAL PARAMETERS .................................................................................................................. 4 SOIL PARAMETERS ............................................................................................................................. 5 MATERIAL PROPERTIES ....................................................................................................................... 5 DESIGN BASIS ................................................................................................................................... 5
LOADING ........................................................................................................................................ 6 3.1 3.2 3.3 3.4
4.
ABOUT THIS REPORT ........................................................................................................................ 3 ABOUT THE STRUCTURE ...................................................................................................................... 3 ANALYSIS PROCEDURE ........................................................................................................................ 3
BEAM DESIGN ................................................................................................................................. 38 COLUMN DESIGN ................................................................................................................................ 38
SLAB DESIGN .................................................................................................................................... 39 STAIRCASE DESIGN ............................................................................................................................ 40 FOOTING DESIGN .............................................................................................................................. 43
CONCLUSIONS ................................................................................................................................ 52
1. INTRODUCTION 1.1
About this REPORT
This report deals with methodology of the structural analysis and design of a residential building and its results. This report includes different parameters for the analysis and design of the structure. The design results are shown in a very convenient tabular format. The principal aim of the structural design is to prepare necessary construction detail of structural system so as to possess adequate strength, stiffness and stability during the action of all possible loads in its life span. Accordingly, the structural design data are presented in the report.
1.2
About the Structure
The structure which is analysed and design is a three storied residential building. It is going to be constructed it Gokarneswor. It is a RCC‐Framed structure.
1.3
Analysis procedure
The structure has been modelled, analysed and designed in a computer software “SAP2000”. The software has very good analysis and design capability which are verified in the verification problems included in the package. It is a Finite Element Method (FEM) based software and requires modelling of the structure by finite‐elements. Beams and columns are modelled with line (or frame) elements, while the slabs and roofs are modelled with area‐elements.
Page 3 of 43
2. DETAILED PARAMETERS OF THE BUILDING Different parameters are listed below.
2.1
General Parameters Building Type
: Residential Building
Location
: Gokarnashwor Ward No: 01
Owner Plot no
: 457, 460
Site plan area
: 3080.81 sq. ft (As per Lal Purja)
Plinth Area
: 932.08 square feet
No of Storey
: 2.5
Floor Height
: 2.86 m (centre‐to‐centre)
Wall thickness
2.2
: Mrs. Nir Kumari Rai
: 230mm for outer Walls, 115mm for partition
Parapet Height
: 1 m
Total Ht
: 8.58 m
Structural Parameters Foundation Type
: Isolated Footing System : Rectangular:
Columns
:(12”x12” )
Beams
: 9”x14”
Slabs
: Two‐way, 5” (127mm)
Staircase
: 127 mm slab
Walls
: Brick wall non‐load bearing
Structural System
: RCC Special Moment Resisting Frame (SMRF)
Building Height
: 8.58 m
Fundamental Time period
: 0.37sec
Page 4 of 43
2.3
2.4
2.5
Soil Parameters Soil Type
: Medium soil (Type II)
Bearing Capacity
: 150 KN/m2 at foundation level
Material Properties Cement
: Ordinary Portland cement (OPC)
Concrete Grade
: M20 for all beams, columns, slab and staircase…
Steel Grade (for reinforcement)
: Fe500
Design Basis
The building is designed following the standard codes and norms. The different codes used for the structural design are i. ii. iii. iv. v.
IS456:2000 [Code of practice for plain and reinforced concrete] for Design of Concrete Structures. IS1893:2002 [Criteria for earthquake resistant design of structure] for Earthquake load calculation. IS875:1987 [Code of practice for design loads (other than earthquake) for buildings and structures] for Other Load calculation. SP16:1980 [Design aids for reinforced concrete to IS456:1978] for design of the structural members. IS13920:1993 [Ductile detailing of reinforced concrete structures subjected to seismic forces] for Ductile Detailing of the structural members.
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3. LOADING All loadings are derived bases on different parts of IS875. Earthquake load is calculated based on IS1893:2000.
3.1
Dead Loads (DL)
These are the permanent load which is not supposed to change during the structure’s design life. The dead loads included in the design are: a. Self‐weight of the structure i. RCC (beams and columns) : 25 KN/m3 ii. RCC (slab) : 25 KN/m3 iii. Steel: 78.5 KN/m3 b. Wall‐loads i. 2.4m full ht wall 9” wall=11kN/m 4” wall=6kN/m (30% opening is considered wherever necessary) ii. 1.0m parapet wall 4” wall=2.5kN/m c. Finishing on floors i. Floors: 1 KN/m2 ii. Staircase: 1.0KN/m2
3.2
Live Loads (LL)
These are the loads that may vary its intensity and/or position during design life. Live loads for different rooms and roofs are calculated as per the functional requirement as specified in IS875 code. a. Live loads on floor i. Room: 2 KN/m2 ii. Balconies : 3 KN/m2 iii. Staircase: 3 KN/m2 iv. Lavatory (toilet): 2 KN/m2 b. Live loads on roof i. Accessible roof: 1.5 KN/m2
3.3
Earthquake Loads (EL)
Earthquake load has been calculated based on IS1893:2000. Basically, horizontal seismic forces shall be considered for the structures that depend on different parameters. Different parameters for generating earthquake loads are:
Page 6 of 43
a. b. c. d. e. f.
3.4
Seismic Zone Zone Factor (Z) Importance Factor Reduction Factor (R) Soil type Spectral Acceleration (Sa/g)
: V (as per classification if IS1893) : 0.36 : 1 (for residential building) : 5 (for SMRF) : Medium : depends on time period and soil type.
g. Hor. Seismic Coefficient (Ah)
: . .
h. Seismic Weight of Bldg (Ws) i. Base Shear (VB)
: DL+0.25LL (for LL≤3) OR DL+0.5LL(for LL>3) : Ah * Ws
Load Combinations
Different load combinations are generated as per IS1893:2002, since earthquake load is considered from same code. The load combinations are: Load Combination
Combination Name
a. 1.5 (DL + LL) b. 1.2 (DL + LL +‐ EL) i. 1.2 (DL + LL + ELx) ii. 1.2 (DL + LL ‐ ELx) iii. 1.2 (DL + LL + ELy) iv. 1.2 (DL + LL ‐ ELy) c. 1.5 (DL +‐ EL) i. 1.5 (DL + ELx) ii. 1.5 (DL ‐ ELx) iii. 1.5 (DL + ELy) iv. 1.5 (DL ‐ ELy) d. 0.9 DL +‐ 1.5 EL i. 0.9 DL + 1.5 ELx ii. 0.9 DL ‐ 1.5 ELx iii. 0.9 DL + 1.5 Ely iv. 0.9 DL ‐ 1.5 Ely
: UDCON2 :UDCON3 :UDCON4 :UDCON5 :UDCON6 :UDCON7 :UDCON8 :UDCON9 :UDCON10 :UDCON11 :UDCON12 :UDCON13 :UDCON14
where: DL = Dead Loads LL = Live Loads EL = Earthquake load ELx = Earthquake load in +ve x‐direction ELy = Earthquake load in +ve y‐direction
Page 7 of 43
4. DESIGN CRITERIA The concrete structures are designed using Limit State Method which is incorporated in IS456:2000.
4.1
Limit State Method
It is based on safety and serviceability requirements associated with the design loads and design strengths of the materials. These design loads and design strengths are obtained by applying partial safety factors for characteristic loads and strengths of the materials as concrete and steels. The limit state method of design covers different criteria for design. The two major criteria are a. Limit State of Collapse: The limit state of collapse of the structure or part of the structure could be assessed from rupture of one or more critical sections and from buckling due to elastic or plastic instability (including effects of sway where appropriate) or overturning. The resistance to bending, shear, torsion and axial loads at every section shall not be less than the appropriate value at that section produced by the probable most unfavourable combination of loads on the structure using the appropriate partial safety factors. b. Limit State of Serviceability: It includes limit for deflection and cracking or local damage. Excessive deflection and cracks adversely affects the finishes, efficiency and appearance of the structure and it may impair protection to embedded reinforcements too. Cracking Limit state: the surface width of the cracks should not, in general, exceed 0.3mm in members where cracking is not harmful and does not have any serious adverse effects upon the preservation of the reinforcing steel nor upon the durability of the structure. Deflection limit states for concrete members are: i. The final deflection due to all loads including the effects of temperature, creep and shrinkage and measured from the as‐cast level of the supports of floors, roofs and all other horizontal members, should not normally exceed span/250 ii. The deflection including the effects of temperature, creep and shrinkage occurring after erection of partitions and the application of finishes should not normally exceed span/350 or 20mm whichever is less.
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5. MODELLING OF THE STRUCTURE The structure is modelled in SAP2000 v 19 Three Dimensional Views
Figure 3‐D view of building
Page 9 of 43
5.1
Grids and Node Numbers at Base Level
Page 10 of 43
5.2
Columns and Beams Sections
Page 11 of 43
5.3
Loading on the structure
MASONARY WALL LOAD IN BEAMS
Page 12 of 43
STAIR DEAD LOAD IN BEAMS
STAIR LIVE LOAD IN BEAMS
NOTE:
• •
The loads on slab like Live load, Floor Finish,Internal wall etc. are assigned as code and the values are mentioned at earlier pages. The parapet wall load in beams is calculated and assigned with values 2.5KN/m.
Page 13 of 43
6. ANALYSIS OF THE STRUCTURE The structure is analysed in SAP2000 non linear version 19. Different analysis outputs are shown.
6.1
Support Reactions
Joint reactions at Footing Level
Page 14 of 43
6.2
BMD,SFD,AFD,Torsion DIAGRAM (ENVELOPE)
MOMENT 3-3
Page 15 of 43
V 2-2
Page 16 of 43
AXIAL FORCE
Page 17 of 43
TORSION
Page 18 of 43
TABLE: Modal Periods And Frequencies
TABLE: Auto Seismic Loads To Horizontal Diaphragms
Page 19 of 43
7. DESIGN OF THE STRUCTURE 7.1
Design of Columns and Beams
Analysis and design of the structure is done by SAP2000 non linear version 19 The required longitudinal reinforcement of the column and beam are as follows:
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LONGITUDINAL REINFORCEMENT PLAN VIEW
FIRST FLOOR
Page 21 of 43
SECOND FLOOR
ROOFFLOOR Page 22 of 43
LONGITUDINAL REINFORCEMENT Y-Z VIEW
A-A
B-B
Page 23 of 43
C-C
D-D
Page 24 of 43
LONGITUDINAL REINFORCEMENT X-Z VIEW
1-1
Page 25 of 43
2-2
3-3
Page 26 of 43
Project CRITICAL BEAM Job Number Engineer
SAP2000 Indian IS 456-2000 BEAM SECTION DESIGN L=4445.000 Element Station Loc Section ID Combo ID
: : : :
26 4295.000 beam UDCON9
Type: Ductile Frame
D=355.000 ds=0.000 E=22360.680 fy=500.000
B=230.000 dct=25.000 fc=20.000 fys=500.000
Units: N, mm, C
(Summary)
bf=230.000 dcb=25.000 Lt.Wt. Fac.=1.000
Gamma(Concrete): 1.500 Gamma(Steel) : 1.150
Factored Forces and Moments Factored Factored Mu3 Tu -45832171 3586836.394
Factored Vu2 73198.358
Factored Pu 91122.260
Design Moments, Mu3 Factored Torsion Moment Mt -45832171 5366494.349
Positive Moment 0.000
Negative Moment -51198665
Longitudinal Reinforcement for Moment and Torsion (Mu3, Tu) Required +Moment -Moment Minimum Rebar Rebar Rebar Rebar Top (+2 Axis) 414.155 0.000 414.155 175.272 Bottom (-2 Axis) 207.077 0.000 0.000 207.077 Shear Reinforcement for Shear and Torsion (Vu2, Tu) Rebar Shear Shear Shear Asv/s Ve Vc Vs 0.578 87663.717 43825.366 68790.256
Shear Vp 36437.047
Torsion Reinforcement for Torsion and Shear (Tu, Vu2) Rebar Torsion Shear Core Asvt/s Tu Vu b1 0.456 3586836.394 73198.358 200.000
Core d1 325.000
7/14/2017 1:25 PM Page 27 of 43
Project Job Number Engineer
SAP2000 Indian IS 456-2000 COLUMN SECTION DESIGN L=2870.200 Element Station Loc Section ID Combo ID
: : : :
81 2870.200 col UDCON10
Type: Ductile Frame
B=300.000 E=22360.680 fy=500.000 RLLF=1.000
D=300.000 fc=20.000 fys=500.000
CRITICAL COLUMN
Units: N, mm, C
(Summary)
dc=56.000 Lt.Wt. Fac.=1.000
Gamma(Concrete): 1.500 Gamma(Steel) : 1.150
AXIAL FORCE & BIAXIAL MOMENT DESIGN FOR Pu, Mu2, Mu3 Rebar Design Design Design Factored Area Pu Mu2 Mu3 Mu2 1170.338 60893.677 9194291.225 43875241.2 9194291.225 AXIAL FORCE & BIAXIAL MOMENT FACTORS K L Initial Factor Length Moment Major Bending(M3) 1.000 2870.200 17550096.47 Minor Bending(M2) 1.000 2870.200 -4801892.5
Factored Mu3 43875241.2
Additional Minimum Moment Moment 0.000 1217873.549 0.000 1217873.549
SHEAR DESIGN FOR Vu2,Vu3 Major Shear(V2) Minor Shear(V3)
Rebar Asv/s 0.333 0.333
Shear Vu 29616.070 23574.763
JOINT SHEAR DESIGN (INFORMATIVE ONLY) Joint Shear Ratio Major Shear(V2) 0.262 Minor Shear(V3) 0.237
Shear VTop 0.000 0.000
Shear Vc 46108.408 46108.408
Shear Vs 29280.000 29280.000
Shear Vp 25977.599 23574.763
Shear VuTot 105422.575 95256.496
Shear Vc 0.402 0.402
Joint Area 90000.000 90000.000
(1.1) BEAM/COLUMN CAPACITY RATIOS (INFORMATIVE ONLY) Major Minor Ratio Ratio 0.550 0.499
7/14/2017 1:16 PM Page 28 of 43
BEAM REINFORCEMENT PROVIDED REINFORCEMENT END
STOREY TOP 603 mm
603 mm
TOP
2‐16Ø TH +1‐12Ø EXT
2
515 mm
2‐16Ø TH +1‐16Ø EXT
Second Floor Beam Roof Floor, Plinth & Foundation Beam
BUTTOM
2‐16Ø TH +1‐16Ø EXT
First Floor Beam
INTERMEDIATE
2
BUTTOM
2‐16Ø TH
2‐16Ø TH
2
402 mm2
402 mm
2‐16Ø TH +1‐12Ø EXT 2‐16Ø TH
2
515 mm
2
402 mm
2‐16Ø TH 2
402 mm2
2‐12Ø TH
2‐12Ø TH
2‐12Ø TH
2‐12Ø TH
2
2
2
226 mm2
226 mm
226 mm
226 mm
STIRRUPS: S1: 8mm @100 mm C/C S2: 8mm @ 150 mm C/C
COLUMN REINFORCEMENT PROVIDED STOREY
REINFORCEMENT
First storey C1 (12"*12")
4‐16mm + 4‐12mm
1257
4‐16mm + 4‐12mm
1257
4‐16mm + 4‐12mm
1257
Second storey C1 (12"*12") Third storey C1 (12"*12")
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AREA (mm2)
Slab Design Slab thickness t
125 mm 20 MPa 500 MPa
Concrete Steel
fck fy
Loading Slab Load Dead Load Live Load FF+WALL Load Total Load Factored Load
DL LL WL Ws Wsu
Slab Data Slab Type Load Longer Span (ly) Shorter Span (lx)
3.125 KN/m 2.000 KN/m 2.500 KN/m 7.625 KN/m 11 KN/m
Regular 11 KN/m 4.44 m 4.44 m
Loading on edges Wlonger
17 KN/m
Wshorter
17 KN/m
.=w*lx/2
Thickness Check Deflection
OK 16 mm
Area of Steel
Sunken Slab Load DL Dead Load Filler Load FL LL Live Load Finishes Load WL Wsk Total Load
3.125 KN/m 5 KN/m 3.0 KN/m 1.0 KN/m 11.74 KN/m
Factored Load Wsku
18 KN/m
one way .=w*lx 2 / 8
+
two way 2 .=(w*lx/2) + (1-(1/3)*(lx/ly) )
two way = αx * w*lx 2 .= αy * w*lx 2
13 KN-m
.=Mulim > Mux or Muy 4 .= 5*W*l /(384EI)
Astx
Asty
298 sqmm
Refer Chart 4 SP 16 pg 21
or
298 sqmm Refer Table 5-44 SP 16 pg 51-80
Spacing required in mm 8# x y 169 c/c 169 c/c
10# 12# x y x y 264 c/c 264 c/c 380 c/c 380 c/c
.=ast of bar*1000/ast req
Final Ast provided
1.00
.=w*lx/3
Moments 13 KN-m
325 mm
ly/lx ratio Slab type
one way
Mx My
Sunken Depth
x
y 8# 150 c/c
8# 150 c/c
Page 30 of 43
16# x 676 c/c
x 676 c/c
DOG ‐LEGGEED STAIRCASE DESIGN
RB
RA
T1 L1 0.23
F1 0
L2 1.42
T2 1
Fw 0.23
g 1 0.05
Fw
Thickness floor to of waist Total floor ht(H) slab(t) depth(D) Riser Tread 1 0.175 0.25 2.86 0.106 0.127
t= (1/20 to 1/25)of span
Page 31 of 43
T3 0.23
T4 0.23
Load per m horizontal width In going portion
Effect ive Span( l)m 2.65
Self wt of waist slab(w'g) kN/m
Self wt of waist slab Wt of on plan(wg) steps(wst) kN/m kN/m
3.175 3.8755814
2.1875
Total load on going per meter Total hor. Dead L.L Width load(wd (kN/ (W) ) kN/m m2) kN/m
FF Wt of steps(wf) kN/m 1
7.0631
Factore d load on going portion (wu)kN/ m Wg
3 10.06 15.095
fck
Xu lim fy 20 0.115
500
Page 32 of 43
In Landing portion
L.L 2 Total(wd) (kN/m )
Wf 3.175
Total load on landing per meter hor. Width( W) kN/m
1
4.175
3
Factore d load on landing portion (wu)kN/ m
7.175 10.7625
Xu lim Fe250 Fe415 Fe500 0.53d 0.48d 0.46d d=t 0.1325 0.12 0.115
Design Moments and calculated Ast
RAorRB
Max Moment i.e. Moment at mid span Mu kN‐m Xu lim
17.336 17.59699
Distributio n bars are provided Spacin Adopte as 0.12% of Mu lim Mu lim kN‐ kN‐m˃ Ast g (s) d (S) gross sec 2 mm ɸ mm mm mm area ɸ mm m Mu
0.115
Singly reinfor ced 47.7756 section
424
12 266.58
RAorRB for load applying on the frame RAorRB RAorRB From DL From LL DLoads/m LLoads/m 7.58241 4.0425625 7.3974759 3.94396341
Page 33 of 43
180
152.4
Adopte Spacing d (S) (s) mm mm
8 329.659
200
1
Footing Size Design
F3
Load Design Load
Pu P
394 KN 289 KN
Mux Muy
3 KN-m -4 KN-m
Column size
cx cy
300 mm 300 mm
SBC
q
150 KN/sqm
A req
1.93 sqmm
L B A prvd
1.50 meters 1.50 meters 2.25 meters
Zx Zx
0.56 0.56
Nup
127 KNm2
Moment in x dir Moment in y dir
Footing Size required Footing Size Provided Area Provided
Net upward pressure
Footing Size OK
2
Slab Design lx ly
0.600 0.600
Bending Moment in x dir Bending Moment in y dir
Mx My
34 KN-m 34 KN-m
Concrete Steel
fck fy
20 MPa 500 MPa
dmin
114
D c d' d'
500 mm 50 mm 56 mm 444 mm
Minimum Depth Required Depth Provided Clear Cover Effective Cover Effective Depth
Spacing c/c in mm 16# 12# 533 sqmm 212 c/c 377 c/c 533 sqmm 212 c/c 377 c/c Minimum Ast required across x direcion Minimum Ast required across y direcion Area of Steel
Ast across x direction Ast across y direction
12 mm dia @ 125 mm c/c 12 mm dia @ 125 mm c/c
Page 34 of 43
20# 590 c/c 590 c/c
905 sqmm 905 sqmm
Design Of Isolated Footing 3
One Way Shear along x direction Vu1 ζv
45 KN 0.067 MPa
ζc
0.260 MPa 173 KN
Vc1
One Way Shear Check OK 4
One Way Shear along y direction Vu1 ζv
45 KN 0.067 MPa
ζc Vc1
0.260 MPa 173 KN
One Way Shear Check OK
5
Two Way Shear Vu2 ζv
324 KN 0.245 MPa
ks*ζc Vc1
1.118 MPa 1477 KN
Two Way Shear Check OK
Page 35 of 43
2 of 3
Design Of Isolated Footing
3 of 3
L= 1.50 meters
500 mm
B= 1.50 meters
300
300
200 mm
12 mm dia @ 125 mm c/c
Page 36 of 43
12 mm dia @ 125 mm c/c
Design Of Isolated Footing 1
1 of 3
Footing Size Design F2 Load Design Load
Pu P
500 KN 367 KN
Mux Muy
5 KN-m 1 KN-m
Column size
cx cy
300 mm 300 mm
SBC
q
150 KN/sqm
A req
2.44 sqmm
L B A prvd
1.80 meters 1.80 meters 3.24 meters
Zx Zx
0.97 0.97
Nup
117 KNm2
Moment in x dir Moment in y dir
Footing Size required Footing Size Provided Area Provided
Net upward pressure
Footing Size OK
2
Slab Design lx ly
0.750 0.750
Bending Moment in x dir Bending Moment in y dir
Mx My
49 KN-m 49 KN-m
Concrete Steel
fck fy
20 MPa 500 MPa
dmin
136
D c d' d'
500 mm 50 mm 56 mm 444 mm
Minimum Depth Required Depth Provided Clear Cover Effective Cover Effective Depth
Spacing c/c in mm 16# 12# 533 sqmm 212 c/c 377 c/c 533 sqmm 212 c/c 377 c/c Minimum Ast required across x direcion Minimum Ast required across y direcion Area of Steel
Ast across x direction Ast across y direction
12 mm dia @ 125 mm c/c 12 mm dia @ 125 mm c/c
Page 37 of 43
20# 590 c/c 590 c/c
905 sqmm 905 sqmm
Design Of Isolated Footing 3
One Way Shear along x direction Vu1 ζv
97 KN 0.121 MPa
ζc
0.260 MPa 208 KN
Vc1
One Way Shear Check OK 4
One Way Shear along y direction Vu1 ζv
97 KN 0.121 MPa
ζc Vc1
0.260 MPa 208 KN
One Way Shear Check OK
5
Two Way Shear Vu2 ζv
471 KN 0.356 MPa
ks*ζc Vc1
1.118 MPa 1477 KN
Two Way Shear Check OK
Page 38 of 43
2 of 3
Design Of Isolated Footing
3 of 3
L= 1.80 meters
500 mm
B= 1.80 meters
300
300
200 mm
12 mm dia @ 125 mm c/c
Page 39 of 43
12 mm dia @ 125 mm c/c
DESIGN A STRAP FOOTING when the external column is very near or on the property line Given: fck fy Bearing capacity of soil‐ fb Boundry column‐A la ba Column‐B lb bb Factored load on col.A Factored load on col.B c/c distance bet. Columns (a) Proportioning of the Base Working load on col.A Working load on col.B Self wt. Of footing‐10%(PA+PB) Total working load Required area of footing‐Af Provide width of footing‐Bf
20 n/mm² 500 n/mm² 150 kn/m² la
304.8 mm 304.8 mm
lb
304.8 304.8 263 500 4.44
ba
bb
mm mm kn kn m
175.33333 333.33333 50.866667 559.53333 3.7302222 1.5
kn kn kn kn m² m
0.921115 1.5 0.9868148 1.7 4.8 763 158.95833
m m m m m² Kn Kn/m²
304.8 355 0.5725 1000 26.049794 97.151073 450 200
mm mm m mm Kn‐m mm mm mm
Not factored Not factored
Bf b1
b2 Lf1
Lf2
Lf1 Provided Lf1 Lf2 Provided Lf2 Area provided‐Af Total ultimate load from columns Upward intensity of soil pressure ‐Pu/Af (b) Design of footing slab max. Width of column Let the width of strap beam‐b Cantilever projection of slab beyond beam Consider 1m width of slab Max. Ultimate moment Required‐d1 Provided depth‐d1 d2
Page 40 of 43
For drawing
d1 d2 Use dia of steel Provided effective depth‐d1 Required‐Ast spacing provide c/c dist of bar Area provided tuc pt 0.15 0.28 0.25 0.36 Shear resisted by conc.‐Vuc Vud Distribution steel:Requid.Ast Assume dist. steel dia spacing Say (c) Design of strap Beam Net upward pressure/ m length of beam‐wu Downward pressure under col.A‐w1 Downward pressure under col.B‐w2
12 394 153.56363 736.1118 150 753.6 0.191269 0.3130152 49.756379 28.374063 540 12 209.33333 150
mm mm mm² mm mm mm² % N/mm² KN KN mm² mm mm mm
For drawing
For drawing
<
OK
238.4375 KN/m 862.86089 KN/m 1640.4199 KN/m
col‐A
col‐B
Bf b1
b2 Lf1
Lf2 0.6976
C D
E
F
G
H J
0.3048
K
SF at the inner face of the col.A SF at the edge E of the footing SF at edge F SF at the inner edge of col.B SF at outer edge of col.B Point of zero SF from inner face D of col.A
‐190.3243 94.65625 94.65625 260.99025 ‐166.334 0.7982144
KN KN KN KN KN M
MuK MuE MuH MuG MuF Max hogging moment (nagative) Required depth d
‐104.9652 ‐86.17661 58.017299 43.591687 ‐80.45781 104.9652 333.40159
KN‐M KN‐M KN‐M KN‐M KN‐M KN‐M mm
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Tension at top
Provide Total depth of beam Effective depth, d Required Ast at top Assume dia of bar no. of bars required Steel at bottom of beam Min.steel required Provide Assume dia of bar no. of bars required
550 mm For drawing 500 mm 521.08325 mm² 16 mm 2.59297 nos Provide 3 nos of 16 mm dia at top 277.74466 mm² 301.75 mm² 301.75 mm² 16 mm 1.5015426 nos Provide 3 nos of 16 mm dia at bottom 177.5 mm² 12 mm 1.5702406 nos 2 nos of 12 mm dia at both faces of beam
Side face reinforcement Assume dia of bar no. of bars required Provide Design of Shear reinforcement: Max shear at face of col.A 190.32425 KN pt 0.3396507 % INTERPOLATION for tuc value % steel τuc Input heigher value from table 0.25 0.36 Input lower value from table 0.5 0.48 τuc 0.403032 N/mm² Shear resisted by concrete 71.53824 KN Shear resisted by min.stirrups 71 KN Shear to be resisted by vertical stirrups 118.78601 KN Assume dia of stirrups 8 mm Assume legs of stirrups 2 Spacing s 183.98126 mm say 100 mm zone of shear reinforcement 189.72645 mm say 1m provide 8 mm 2 legged stirrups for 1 m dist. From D to N Min. shear reinforcement: Assume dia of stirrups 8 mm Assume legs of stirrups 2 Spacing s 307.80845 mm say 150 mm provide 8 mm 2 legged stirrups for other dist.
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8. CONCLUSIONS A Residential building has been fully designed using a computer program, SAP2000 nonlinear version 19. All the required design details has been calculated and presented. Best‐approach has been adopted for most‐economical design, yet fulfilling all the requirements for important building. Due considerations has been given to all room requirements and probable increase in load. Reinforcements are quite satisfactory and they are so balanced for easier material handling and concreting. Due attention has been made in reinforcement congestion and size and number of bars are balanced for easiest and safest construction. In some places, more than required reinforcement is provided for feasibility during construction. During construction, it is mandatory to follow IS13920, regarding provision of stirrups and ties, development lengths, splices and other detailing.
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