Power Generation Engineering And Services Company

1. Power Generation Engineering And Services Company Department of Civil Engineering Structural Design Central Group Modeling of Composite Steel Floors Using GT STRUDL A Presentation Submitted to: GT STRUDL Users Group 24th Annual Meeting & Training Seminar To Address Application of GT STRUDL for Structural Analysis of composite steel section February, 2012

2. Power Generation Engineering And Services Company PGESCo. • PGESCo stands for (Power Generation Engineering Services Company) • Established in 1994 • Located in Cairo, Egypt • Focused on EPCM (Engineering, Procurement, Construction and Management) • Produced more than 20,000MW

3. Rendered View of a Combined Cycle Power Plant CTG / STG CTG ( Combustion Turbine Generator)/ STG (Steam turbine Generator) 3

4. Structures in power plants where composite slabs are used: • Steam Turbine Generator “STG” Building. • Combustion Turbine Generator “CTG” Building. • Control building. • Electrical building. • Circulating Water Electrical Building “CWEB”.

5. Control building during construction: 5

6. Control building model using Gtstrudl: • Model include • structural steel • upper part and the • concrete lower part • (Walls and Slab) • -Concrete slab • is represented by big • horizontal X brace to • simulate rigid • diaphragm action. The • purpose of this study is • how to model the slab • as a diaphragm and a • support for gravity • loads. 6

7. Models used to simulate Composite Steel Floor 1- Full model 2- Springs were used to replace beams to control deflection 3- Plate elements were deleted at corners only. 4- Plate elements on the girders were deleted to insure floor was not spanning between girders. 5- Element has one direction 6- Sequential analysis 7- Rigid element between beam & slab 8- Master & Slave 9- Eccentricity between the centerline of plate and steel beams. 7

8. Criteria for the normally used design model. • Bending moments in the slab, approach approximate values • obtained using continuous beam analysis results (confirm one • way action), • Bending moments in beams (confirm transverse beams support • of the concrete slab) • Bending moment in the Girders (Confirm Girders support of the • transverse beams). • Lateral deflection ( Confirm rigid diaphragm action by the • concrete slab) • The above 4 limits will be compared with a MANUAL • calculation • Asimpler structure than the control building will be used for this case study. 8

9. Simple structure: • Slab thickness 200mm • Gravity Load 1.0 metric tons/m2 (200psf) • Lateral Load 10.0 metric tons (22.0 kips) • Hinged supports at column bases. 9

10. ManualCalculation: Girder Column Filler beam 10

11. ManualCalculation: • For Concrete Slab:- 11

12. ManualCalculation: • For steel filler beams:- • The steel (filler) beams behave • simply supported on steel girders. • Steel beam span (L) = 10.0 meters. • Beam uniform load (w) = slab • uniform load * spacing • =1*2 = 2.0 t/m’ • Maximum bending moment • (M)=2*102/8= 25 m.t (180.8Kip.ft) • Maximum deflection • (Δ) = [5*(2*(1000)4]/[(384*2100*35088)] = 3.53 cm = 35.3 mm (1.39in) • Reaction =2*10/2=10ton (22.04Kip) 12

13. ManualCalculation: • For steel girders:- • The steel girders behave simply • supported on steel columns. • Steel beam span (L) = 10.0 meters. • Steel girder loads are the reaction of • filler beams • Maximum bending moment • M=0.6*10*10=60 m.t (433.9 kip.ft) • Maximum deflection (Δ) = [(0.063*10*(1000)3]/[(2100*56191)] = 5.34 cm = 53.4 mm (2.1in) • Reaction=4*10/2=20 ton (44.1 kip.ft) 13

14. 1-Full model used: • 10m X 10m X 6m high structure. • Braced in one direction & frame • action in the other. • Columns W10X33, and vertical • brace WT5X11 • Girder size of W24X55, and • transverse beams size of W21X44 • Slab thickness 200mm supported by • the steel filler beams. • Gravity Load 1.0 metric tons/m2 (200psf) • Lateral Load 10.0 metric tons (22.0 kips) • Hinged supports at column bases. 14

15. 1-Full model used: Bending in filler beams & girders uniformly loaded 15

16. 1-Full model used: • Bending in slab (Neg. mom.= 0.0) • One way action does NOT exist 16

17. 1-Full model used: Displacement at joints in mm under Load 1 Seems like slab is supporting the filler beams. Hand Calculation shows filler beam max deflection = 35.3 mm (1.39 in) 17

18. 1-Full model used: • GT results are quite different from the results obtained by the • manual calculation because of the combined action of the slab • and the steel beams. • Each of the upcoming trials has its own perspective in choosing • the methodology to represent the composite action of floor • beams. • Each model presented a different set of problems simulating • composite action. • A comparison of the results will be made with manual • calculation. The results will be evaluated to understand the • reasons for differences of the results from those of manual • calculations. 18

19. 2-Springs used to control deflection • Solve the beam manually for uniform load W obtained by multiplying the area uniform load by beam spacing • Calculate the deflection @ 0.5m intervals(0.5m X 0.5m Plate elements) • Multiply the uniform load by 0.5m to get concentrated load • Divide the concentrated load by the deflection • calculated manually at this point to get stiffness 19

20. 2-Springs used to control deflection • This stiffness used represents the steel beam. • In the model the steel beams are replaced by the calculated spring constants. This model cannot be used simply because the added springs generate vertical reactions that are not transmitted to the columns which generate lower reaction loads at the columns. 20

21. 3-Delete plates at corners only • Delete elements at the corners to prevent the slab from being directly supported by the columns 21

22. 3-Delete plates at corners only • Bending moment • in the steel beam 22

23. 3-Delete plates at corners only • Bending moment in the • slab 23

24. 4- Delete plate elements on the girders • Delete the plate elements that rest on the • girder to force the slab to • transfer the load to the • beams then to the girders • then to the columns 24

25. 4- Delete plate elements on the girders • Bending moment • in the steel beams 25

26. 4- Delete plate elements on the girders • Bending moment in the • slab 26

27. 4- Delete plate elements on the girders • Vertical displacement 27

28. 5- Element has one direction of distribution • PSRR element type are used in modeling • The problem that the PSRR elements do not • permit the consideration of bending stiffness • analysis nor the dynamic analysis 28

29. 6-Sequential analysis • A thought was discussed that the sequential analysis will get GTS to differentiate between the stage when the concrete is wet and the next stage when the concrete hardens. • This approach was not what was thought to be and hence, it was abandoned. 29

30. 7- Rigid elements between beam and slab • This modeling technique did not produce a good representation of the bending moment which can not be explained. 30

31. 8- Use of Master and Slave Joints • This also did not produce a good representation of the bending moment. 31

32. 9- Eccentricity • Eccentric between the steel member and • the concrete plate elements 32

33. 9- Eccentricity • Weird Bending moment diagram which had no explanation. 33

34. 9- Eccentricity • Bending in • the slab 34

35. Models used to simulate hand calc till now 1-Full model 2-Springs were used to replace beams to control deflection 3-Plate elements were deleted at corners only. 4-Plate elements on the girders were deleted to insure floor was not spanning between girders. 5- Element has one direction 6- Sequential analysis 7- Rigid element between beam & slab 8- Master & Slave 9-Eccentricity between the centerline of plate and steel beams. 35

36. What to do next??? • None of the above modeling techniques produced a good representation of the approximate manual approach. So a combination of the above modeling techniques will be tried to reach a reasonable representation of the structure with some modification • It was suggested to use a combination of the eccentric modeling approach together with the deleted elements at the corners for: • Easy to model “applicable for every day work” • Actual representation of the differences between the steel beam CL and the concrete slab CL. • The modification will be by varying one of the following parameters • Thickness of the slab • Young's Modules of the concrete slab 36

37. Variation in Thickness for the slab 37

38. Variation in Thickness for the slab 38

39. Variation in E for concrete 39

40. Variation in E for concrete 40

41. Variation in E for concrete • Bending moment • in the steel beam • Case = 0.25% E 41

42. Variation in E for concrete • Bending moment • in the slab • Case= 0.25% E 42

43. Variation in E for concrete • Lateral difflection in Z • direction • (Braced Dir.) 43

44. Variation in E for concrete • Lateral deflection in X • direction • (Moment frame dir.) 44

45. Verification – Other Software Comparing results to those obtained by using another software an other program with a composite beam module built in 45

46. Verification – Other software 46

47. Conclusion • Using the Eccentric model with the deleted shell element at the corner with a reduction in the E of the concrete slab, produces results in agreement with the manual calculations. The following table summarize these results. 47

48. Questions and Discussion