Class 2 Continuous Load Path Concepts

1. Class 2Continuous Load Path Concepts

2. Load Paths • Loads must go to “ground” • Vertical loads • Gravity • Uplift • Lateral loads • Wind • Earthquake • Flood Building Design – Fall 2007

3. Load Paths • Bridge loads • Headers • Beams • Girders • Interaction with the ground • Shallow – spread, slab, stem wall • Deep – piles, caissons, friction, bearing • Possible failures – slope failure, liquefaction, erosion, excessive moisture Building Design – Fall 2007

4. Load PathsVertical Building Design – Fall 2007

5. Deck collapse – gravity failure Building Design – Fall 2007

6. Foundation gravity failure Building Design – Fall 2007

7. Uplift failure Building Design – Fall 2007

8. Uplift column failure Building Design – Fall 2007

9. Flood Building Design – Fall 2007

10. Lateral displacement Building Design – Fall 2007

11. Earthquake Building Design – Fall 2007

12. Wind Building Design – Fall 2007

13. Vertical and Lateral paths OK Building Design – Fall 2007

14. Lateral failure from wind Building Design – Fall 2007

15. Lateral wind failure Building Design – Fall 2007

16. Slope failure Building Design – Fall 2007

17. Masonry piers Building Design – Fall 2007

18. Beams – carrying loads Building Design – Fall 2007

19. Headers: bridging loads Building Design – Fall 2007

20. WTC-7 (Bridging loads failure) • 47 story building • housed city’s OEM • some missile impacts • burned uncontrolled for 8 hours • 7 story electric substation • diesel fuel in building in several tanks Building Design – Fall 2007

21. Building Design – Fall 2007

22. WTC 7 - 7th Floor Plan Building Design – Fall 2007

23. Building Design – Fall 2007

24. WTC 7 Penthouses start to collapse Building Design – Fall 2007

25. WTC 7 Interior collapse continues - note the “kink” Building Design – Fall 2007

26. Building Design – Fall 2007

27. Building Design – Fall 2007

28. Load Path Concepts • Materials chosen with sufficient strength • Connections made with sufficient size, strength, and number • Any weak link could be a failure point • Load path requires appropriate soil bearing capacity • Soil must be able to maintain bearing capacity Building Design – Fall 2007

29. Vertical gravity loads • Creates compression in members • Creates shear in connections • What materials and connections perform well in compression? Building Design – Fall 2007

30. Vertical gravity loads • Masonry • Concrete • Steel • Wood (of proper size) • Reinforcing steel for masonry and concrete • Bolts Building Design – Fall 2007

31. Vertical gravity load • Compression failures are most likely…? • Buckling Building Design – Fall 2007

32. Vertical uplift loads • Creates tension in members • Creates shear or withdrawal in connections • What materials and connections perform well in tension? Building Design – Fall 2007

33. Vertical uplift loads • Steel • Wood • Bolts or welding for steel • Bolts for wood Building Design – Fall 2007

34. Lateral loads • Creates compression in wall panels • Creates bending in single members • Creates shear at panel edges • Creates compression in struts between panels or members Building Design – Fall 2007

35. Homework 1 – Due 9/12/07 • Find and mark the load paths on the 2 attached sketches • Sketch headers, girders or beams as bridging loads • Take the loads into the foundation which is a pile system Name: ____________________________ Building Design – Fall 2007

36. Building Design – Fall 2007

37. Building Design – Fall 2007

38. Pilelayout Building Design – Fall 2007

39. References • Masonry Structures – text by Drysdale • Design of Wood Structures – text by Breyer • ASCE 7 • ACI 530 • NDS • Class web page Building Design – Fall 2007