BRE/TSLAB Vulcan Comparisons. Roger Plank Anthony Abu & Ian Burgess

Transcription

1 BRE/TSLAB Vulcan Comparisons Roger Plank Anthony Abu & Ian Burgess

2 Tensile Membrane Action Tensile Area Peripheral compression

3 BRE Bailey Method Rigid plastic theory with large change of geometry Yield line capacity Membrane enhancement to yield line capacity Panels are horizontally unrestrained Vertical support at the boundaries Tensile strength of concrete is ignored

4 C L BRE Bailey Method nl C φ S S T 2 T 2 T 2 T2 T 2 T 1 l

5 BRE Bailey Method Allowable deflection v = α ( T T ) 19.2h l y L + E f 3 8 T 2 -T 1 = 770 C for Time 90 mins T 2 -T 1 = 900 C for Time > 90 mins

6 Comparison between Vulcan and BRE Bailey Method Do protected beams provide adequate vertical support? Effect of reinforcement ratios on failure Effect of tensile strength of concrete Effect of edge continuity

7 Slab-Panel Properties 9.0m x 6.0m, 7.5m x 9.0m, 9.0m x 9.0m, 9.0m x 12.0m S275 beams Trapezoidal deck profile Normal weight concrete Strength (f cu = 40N/mm 2, f ck = 35N/mm 2 ) S500 Reinforcement mesh Average mesh position (from top surface) = 45mm

8 Slab-Panel Properties

9 7.5m x 9.0m Slab-Panel Corner vertical support Different protection regimes and support conditions A193 Mesh 9.0m Load ratios and limiting temperatures Secondary beams = 0.44 and 631 C Primary beams = 0.40 and 646 C 7.5m

10 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) 0 60 mins TSLAB v = α ( T T ) 0.5 f l y L h E Span/ BRE Limit v α = o ( 770 C) 19.2h l f E y 3L Time (min)

11 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) Bailey - BRE Method Time (min)

12 7.5m x 9.0m Slab-Panel

13 7.5m x 9.0m Slab-Panel

14 7.5m x 9.0m Slab-Panel

15 7.5m x 9.0m Slab-Panel

16 7.5m x 9.0m Slab-Panel

17 7.5m x 9.0m Slab-Panel

18 7.5m x 9.0m Slab-Panel

19 7.5m x 9.0m Slab-Panel

20 7.5m x 9.0m Slab-Panel

21 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) Vulcan edge support Vulcan corner support Generic Protection Time (min)

22 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) Vulcan Displacement of slab panel centre relative to secondary beam Vulcan Displacement of slab panel centre relative to primary beam Time (min)

23 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) Time (min)

24 7.5m x 9.0m Slab-Panel Vertical Displacement (mm) Vulcan Cold Perimeter Beams Edge support - Tensile strength of concrete included Vulcan Cold Perimeter Beams Edge support - Tensile strength of concrete ignored Time (min)

25 Main Study Maximum absolute vertical displacements Deflection plots (mesh sizes) A142 Navy blue A193 Red A252 Green A393 - Black Analytical approaches BRE Method Solid lines Vulcan Broken lines

26 Proposed Failure Criteria Type 1 Typical slab panel Secondary beam failure Primary beam failure Type 2 Typical slab panel Secondary beam failure Primary beam failure

27 9.0m x 6.0m Slab-Panel Type Maximum Displacement (mm) Maximum Displacement (mm) Time (min) Time (min) Type 1 Vulcan Results Plastic Failure

28 9.0m x 12.0m Slab-Panel Type Maximum Displacement (mm) Maximum Displacement (mm) Time (min) Time (min) Type 1 Vulcan Results Plastic Failure

29 9.0m x 9.0m Slab-Panel Type Maximum Displacement (mm) Maximum Displacement (mm) Time (min) Vulcan Results Time (min) Plastic Failure Type 1

30 Comparison of Failure Times Reinforcement ratios 142, 166, 193, 221, 252, 318, 393 (mm 2 /m) Additional ratios for 9.0m x 9.0m slab panel 153, 179, 206, 236, 284, 354 (mm 2 /m) Comparison of failure times

31 9.0m x 6.0m Slab-Panel Increasing reinforcement ratio Increasing reinforcement ratio Maximum Displacement (mm) Maximum Displacement (mm) Time (min) Time (min) Vulcan failure times BRE failure times

32 Failure Times Failure Time (min) TSLAB BRE Limit Span/20 Failure Time (min) TSLAB BRE Limit Span/ Area of Reinforcement (mm 2 /m) Area of Reinforcement (mm 2 /m) 9.0m x 6.0m comparison 9.0m x 12.0m comparison

33 Conclusions Significant influence of edge support & continuity Bailey Method sensitive to mesh size and temperature Conservative for Smaller mesh sizes Larger slab panels As collapse condition for slab Failure criteria - relative or absolute displacements? Reinforcement temperatures

34 Thank You