Introduction to Cellular Beams Dr Stephen Hicks, Manager Structural Systems, HERA,
[email protected]
Presentation overview
Manufacturing Process
Applications
Design Software
Recent Research
New Developments
Presentation overview
Manufacturing Process
Applications
Design Software
Recent Research
New Developments
Range of Applications
2%
2% 3%
Castellated
10%
Architectural Straig St raight ht Raft R afters ers
15%
Curved Rafters Floors Tapers
68% UK sales stand at just over 30,000 tonnes p.a. (Nov. 2007)
Manufacturing process
Fabrication of cellular beams
Steel beam or column section is cut to create regular openings
Fabrication of cellular beams
Oxycutting N°1
HFINAL HINITIAL
Oxycutting N°2
Fabrication of cellular beams
Final length
Scrap
Flexibility in depth
Ex 533 x 210 UB 82 723 mm deep cells - 450 dia @ 675 crs
822 mm deep cells - 600 dia @ 710 crs
Pre-cambering during the fabricating process
Cellular beams pre-cambered mid-production at NO COST
Creating Asymmetric Sections The parent section is split to create two top tees
Another section is split to create two bottom tees
Asymmetric cellular beam is created by combining tees
Asymmetric Openings
The cutting profile creates an asymmetric opening position
Production - Creating Tapers
By cutting the web along a diagonal and rotating the bottom tee through 180 0 a tapered section is formed.
Production - Creating Tapers
By cutting the web along a diagonal a tapered section can be formed.
Curves
Curves formed mid-manufacturing process.
Range of Applications – Floor beams
Advantages of long-span construction
Long, column free spans
Flexibility & more usable floor area
Less foundations
Faster erection
Reduced fabrication costs
Short Span 9 Beams
Long Span 5 Beams
Quicker Erection
Short Span
Long-span
Depth savings through service integration Raised Floor
Raised Floor
Service Zone Service Zone Suspended Ceiling Suspended Ceiling Short Span
Long-span
Service integration with circular ducting
Incorporation of rectangular services
Cellular beam
Cellular beam with elongated opening
Elongated openings
Secondary Beams
m 1 5 9
6 - 9 m
Secondary beams
Primary beams
m 1 5 9 -
6 - 9 m
m - 3 .6 4 . 2
Primary beams
Cell closures
Le Colisee Phase II, Paris
Le Colisee Phase II, Paris
High span/depth ratio (=39)
Le Colisee Phase II- 18.5m span in 470mm
Le Colisee 16.9m Span Floor Area BS 6472 Base Curve
1.000
R = 4 (0.2%g)
Response Factor
R = 8 (0.4%g) 1.6 Hz along grid-line H
) ² 0.100 s / m ( n o i t a r e l e c c A S M R 0.010
1.6 Hz along grid-line H (with carpet) 2.5 Hz along grid-line H 2.5 Hz along grid-line H (with carpet) 2.5 Hz along grid-line 5 Two men at 1.6 Hz along grid-line H Two men at 2.5 Hz along grid-line H Two men at 2.5 Hz along grid-line 5 Running at 2.5 Hz along H Running at 2.5 Hz along H (with carpet)
0.001 1 Steel Construction
10
Frequency (Hz)
100
Leeds Nuffield Hospital Cellular Beams
Operating Theatres
Clear span
Response factor measured less than 1.0 ( 0.05%g) See SCI P354
Cardington design guidance used to reduce fire protection costs
Range of Applications – Roof beams
Straight Rafters
<20m
Portal (Elastic) Simply Supported
30m
>40m
Straight Rafters
Bridgewater Car Auction 34.0m span, 92 kg/m castellated beam
Rafters … 800 x 210 x 82 kg/m Cellular
Simply-supported Curves
Cyfartha Retail Park, Cardiff
Spans … - 23.0m .. 970 x 229 x 101 kg/m - 32.0m .. 1056 x 254 x 125 kg/m - 44.0m .. 1202 x 292 x 176 kg/m - 53.0m .. 1357 x 305 x 253 kg/m
Portalised Curved Beams
Aldi Distribution Centre, Runcorn. Span 42m 610 x 229 x 101 UB (Plastic design) 700 x 210 x 82 cellular (Elastic design)
Double Curves
Double Curves
Tapered Sections
Over 40 stadia Mostly Tapered:
Chelsea
Carlisle United
Hull Kingston Stadium
Dunfermline AFC
Newcastle Falcons
Columns
Design software
Modes of Failure at Openings
Cracking
Concrete crushing Compression Web-post buckling
Yielding or buckling
Web-post shear
Web buckling
Shear force Tension
Support
Yielding Web-post bending
Vierendeel bending at rectangular opening
Web-post buckling
Cellbeam Version 6.0
SCI software
Checks for SCI updates as opened
Cold & Fire Design
SCI QA audit trail down to code level
Import Export with CSC
RAM link underway
Design optimization through automate facility
Help Screens
Curved Rafters - With Fixity
Add moment and axial to the ends
Recent research
Recent European research programme
Full-scale tests on non-composite and composite beams with regular or isolated web openings to make comparisons with existing software. Development of generalised design guidance for implementation within European steel and composite Standards, Eurocode 3 and 4 (EN 1993-1-1 and EN 1994-1-1). Full-scale fire tests on composite beam with regular web openings. Development of improved manufacturing techniques.
Test 1 – Secondary beam with symmetric cross-section
7.03 m span length 1.80 m width ( L / 4 ) 4 point loads to simulate UDL
End of spans left unconcreted to check influence of local composite action
Test specimen 1 failure modes
Web-post buckling & development of Vierendeel bending failure observed
Test 2 – Primary beam with symmetric cross-section
Test 2A Behaviour at elongated openings
Test 2B Load introduction through secondary beams
Load introduction through secondary beam
Test 2 failure modes
Test 2A - Vierendeel bending developing at elongated opening
Test 2B -Excessive yielding in bottom Tee at mid-span
Test 3 – Secondary beam with asymmetric cross-section
7.03 m span length 1.80 m width ( ~ L / 4 ) 4 point loads
Hybrid beam with Af,b / Af,t = 4 IPE 300 as upper chord HEB 340 as bottom chord
Test 3 failure modes
Web-post buckling between openings 11 and 12
Test 4 - Influence of stiffening cells in non-composite beam
Test 4: Vierendeel mechanism at opening 4
Measured failure load vs. predictions from Cellbeam Test No
Load measured at failure (kN)
Cellbeam Predicted resistance (kN)
Experimental / prediction
1
806
540
1.49
2A
500
436
1.15
2B
780
440
1.77
3
656
276
2.38
4
749
400
1.87
Full-scale fire tests on composite cellular beams
In total, 2 fire tests were undertaken at CTICM Test Station in Maizières-les-Metz :
Test P1: Loaded 7.2 m span composite beam protected with a cementitious spray - Based on Test 3 specimen tested at University of Kaiserslautern.
Test P2: Unloaded 7.2 m span composite beam with protected with a cementitious spray - Based on Test 1 specimen tested at University of Kaiserslautern.
Full-scale fire tests on composite cellular beams
Specimen P1
Specimen P2
Specimen P1 and P2 in furnace at CTICM Test Station Maizières-les-Metz
Specimen P1 (loaded with jacks) and P2
Specimen P1 after failure
Specimen P1 after failure
Improvement of the welding procedures Large scale tests
P
P
310
20
423.7-566.6
1020
1700 - 2000
Improved manufacturing of cellular beams The following 1.7 to 2 m span beam tests were undertaken by University of Kaiserslautern under the direction of Arcelor Profil Luxembourg Research:
1-ss – tw = 8.6 mm, sw = 122mm
2-hs – tw = 8.5/21 mm, sw = 95 mm
3 -ss – tw = 13.5 mm, sw = 63 mm
4-ss – tw = 8.6 mm, sw = 55mm
5-hs – hs – tw = 7.1/21 mm, sw = 55mm
Improvement of the welding procedures Large scale tests
Specimen n°
Upper Profile
1-ss
IPE 400
2-hs
Lower Profile
Span Length [mm]
Total Depth [mm]
Web post width [mm]
Opening Diameter [mm]
IPE 400
1897
558
122
358
HEA 300
HEM 300
1800
475
95
350
3-ss
HEB 400
HEB 400
1940
599
63
422
4-ss
IPE 400
IPE 400
1944
600
55
430
5-hs
IPE 300
HEM 300
1644
482
55
354
6-ss
HEM 300
HEM 300
1559
495
50
334
7-hs
HEB 300
HEM 300
1866
472
123
350
8-hs
HEA 300
HEB 300
1800
415
147
300
Improvement of welding procedures Large scale tests
Improvement of welding procedures Large scale tests
Macrography of weld failure (web thickness 11/21 mm)
New Developments - Ultra Shallow Floor Beam
USFB™
USFB™ Made to any depth
PC Units
Min 75 mm bearing For PC Units
Or metal deck
Min 50mm bearing For Metal Decking
Integrated beams
Integrated beams with deep decking
USFB™
Blackpool – 1.5km of 7.5m long USB 250mm deep 74 kg/m with Comflor deck
Integrated beams with precast hollow core units
Conclusions
In the UK, cellular beams are the most popular form of long-span construction Long, column free spans are provided which permit flexibility in the layout and more usable floor area Design software is freely available which permits calculations to be made rapidly Extensive structural, fire and in situ tests have been undertaken over the last 10-years to develop and validate the design software.
Licensed producers of Cellular Beams
