An Important note from the Principal Investigator Abolhassan ASTANEH-ASL on the document that follows:

Transcription

1 An Important note from the Principal Investigator Abolhassan ASTANEH-ASL on the document that follows: October 9, 2013 The following PowerPoint was presented at a meeting of Civil Engineering Student Honor Society, Chi Epsilon (XE) in 2002 on the Campus of UC Berkeley. Abolhassan ASTANEH-ASL, Ph.D., P.E. Professor and Principal Investigator for the NSF Funded UC Berkeley WTC Project (Duration: to ) 1 of 55

2 By Protection of Buildings Against Terrorist Attacks and the Collapse of the World Trade Center Abolhassan Astaneh-Asl, Ph.D., P.E. Professor University of California, Berkeley Organized by the UC Berkeley Chapter of Chi Epsilon XE Credit:Wtcphotos.com This document is part of the World Trade Center Post-Disaster Reconnaissance and Perishable Structural Engineering Data Collection, a research project funded by the U.S. National Science Foundation at the Univ. of California Berkeley with Prof. Abolhassan ASTANEH-ASL as Principal Investigator ( as the Principal Investigator. Duration of the project was from 10/2001 to 9/2002. Further Information and project archives are at Abolhassan ASTANEH-ASL. "This work is licensed under a Creative Commons Attribution-NonCommercial -No Derivatives License." 2 of 55

3 Dedicated to the memories of all victims of 9/11 attacks and to the firefighters and rescuers who so heroically sacrificed their lives to save others. 3 of 55

4 Outline 1. Terrorist attacks on buildings 2. Protection against the attacks 3. Pentagon 4. World Trade Center 5. Lessons learned and future work 4 of 55

5 Protecting Structures Against Terrorist Attacks 1) Ref: Developing Blast Resistant Structures, A. Astaneh-Asl (UC-Berkeley) and David McCallen (LLNL) 5 of 55

6 Protecting Structures Against Terrorist Attacks Collaborative Work by Abolhassan Astaneh-Asl et al., University of California Berkeley and David B. McCallen et al. Lawrence Livermore National Laboratory 6 of 55

7 The Case of Progressive Collapse of Murrah Building, Oklahoma City, 1995 The car bomb exploded too close to the building, knocking out columns and transfer girders. Then due to progressive collapse, ½ of the building collapse under gravity load. 7 of 55

8 Effects of Blast Waves on the Structure Von Mises Stresses (combined Shear and Normal Stresses) 8 of 55

9 Specimen to Test Floor Catenary Action Cables in the Floor Specimen Floor and Cables Develop Catenary Action 9 of 55

10 Analysis at LLNL and Actual Full Size Test at Univ. of California at Berkeley Vertical Displacement of 20.8 inches A.Astaneh-Asl, D. McCallen, E. Madsen, B. Jones, R. Jong, W. Li, Y.Zhao, 10 of 55

11 World Trade Center Design, Construction, Collapse and; Lessons Learned 11 of 55 Credit:Photographer Unknown

12 The Architect Minoru Yamasaki 12 of 55

13 Yamasaki s Initial Designs, 1960 s 13 of 55 Credit:PANYNJ

14 The problem of elevators and the innovative solution 23 Express Elevators, 1600 foot per minute 72 local elevators 4 freight elevator 16 escalators of 55

15 Site Plan Seven Buildings were built on 16 acre lot. N Credit:PANYNJ 15 of 55

16 Tower Plan Tower had large column-free areas 209 ft 16 of 55 Credit:PANYNJ

17 World Trade Center Structural Aspects 17 of 55 Credit:Photographer Unknown

18 The Structural Engineer Leslie E. Robertson 18 of 55

19 19 of 55 The Structural System

20 The Tube System 20 of 55 Column Section Credit: PANYNJ

21 Floors 21 of 55 Credit: PANYNJ

22 Structural Design Structure of a building is designed to resist combined effects of: 1. Vertical Load (e.g. weight of the building) 2. Lateral Load (e.g. wind and earthquake forces) 3. Temperature, impact and other loads 22 of 55

23 Wind Effects on WTC 23 of 55 Credit:SpaceImages.com

24 Wind Effects on WTC Designed for 140 mile / hr wind Copyright 2001 Abolhassan ASTANEH-ASL 9.5 million ft-kips kips Wind Tunnel Tests Were Conducted 24 of 55

25 Wind Induced Vibrations were controlled by 3M viscous dampers 25 of 55

26 Fireproofing 26 of 55 Credit:NYTimes

27 World Trade Center Construction 27 of 55 Credit:PANYNJPhotographer Unknown

28 Construction of WTC Tower 28 of 55 Credit:PANYNJ

29 World Trade Center The 9/11 Attacks 29 of 55 Credit:Photographer Unknown

30 30 of 55 3-D Plane Hit Areas and Casualties

31 People Trapped in the Upper Floors of Credit: Photo by Jeff Christensen Reuter

32 Plane Impacting the Structure External and Internal Columns as well as floors were damaged in 3 floors 32 of 55

33 Plane Impacting the Structure External and Internal Columns as well as floors were damaged in 3 floors 33 of 55

34 Ensuing Fire External and Internal Columns as well as floors were damaged in 3 floors 34 of 55

35 Ensuing Fires External and Internal Columns as well as floors were damaged in 3 floors 35 of 55

36 Ensuing Fire and Collapse of Floor Joists External and Internal Columns as well as floors were damaged in 3 floors 36 of 55

37 Buckling of Columns due to Long Unbraced Length External and Internal Columns as well as floors were damaged in 3 floors 37 of 55

38 Final Collapse Due to Gravity The damaged floor collapsed dropping top portion on the lower part collapsing the entire structure 38 of 55

39 Causes of Collapse Leading theories on collapse of the towers 1. Fire weakened the floor trusses that connected the exterior and interior columns, causing the trusses to sag and eventually separate from the external walls. 2. Initial impact of the planes was so great that the towers were on the verge of collapsing when the fire weakened external columns. 3. The initial impact caused the weight of the upper floors to be shifted from exterior to interior columns. Copyright 2002, Newsday, Inc. 39 of 55

40 What was done in the aftermath of 9/11 1.National Science Foundation awarded 8 grants to study various aspects of the collapse. UC-Berkeley Project was for structural engineering aspects. 2.FEMA funded a study by Building Performance Assessment Team. 3. A congressional Hearing was held. What is in the planning: 4.NIST will lead a comprehensive study for $40M. 5. NSF is funding research in this field. 40 of 55

41 Post Collapse Investigation of Steel Structure Research Funded by National Science Foundation Photo by William Farrington for A. Astaneh s WTC NSF Project. Copyright 2001 UC Board of Regents 41 of 55

42 Investing Steel Structure Copyright 2001 Abolhassan ASTANEH-ASL Copyright 2001 Abolhassan ASTANEH-ASL Copyright 2001 Abolhassan ASTANEH-ASL Copyright 2001 Abolhassan ASTANEH-ASL 42 of 55

43 An Interior Column hit by the engine? Copyright 2001 Abolhassan ASTANEH-ASL 767 Engine 43 of 55

44 Member Identification Copyright 2001 Abolhassan ASTANEH-ASL 44 of 55

45 45 of 55 Congressional Hearing

46 Fully loaded plane entering the structure and damaging it.. University of California Berkeley and MSC Software Corporation Studies of World Trade Center, Principal Investigator: A. Astaneh-Asl, University of California, Berkeley Sponsor: Civil and Mechanical Systems Program, National Science Foundation 46 of 55

47 Fully loaded plane entering the structure and damaging it.. University of California Berkeley and MSC Software Corporation Studies of World Trade Center, Principal Investigator: A. Astaneh-Asl, University of California, Berkeley Sponsor: Civil and Mechanical Systems Program, National Science Foundation 47 of 55

48 Studies of the World Trade Center University of California, Berkeley and MSC Software Corporation Principal Investigator: A. Astaneh-Asl, Sponsor: National Science Foundation 48 of 55

49 Studies of the World Trade Center University of California, Berkeley and MSC Software Corporation Fire Heatingup Damaged Structure, Weakening it and the Structure Collapses under the Gravity Load. Principal Investigator: A. Astaneh-Asl, Sponsor: National Science Foundation 49 of 55

50 Lessons Learned and Future Work 1. Need better fire protection 2. Need new systems that can prevent progressive collapse economically and in architecturally pleasing manner. 3. Review fire codes and structural engineering codes to ensure protection for important structures against terrorist attack. 50 of 55

51 What can we do about airplanes crashing into buildings? Today s crash of a plane into a 30- story building in Milan Italy 51 of 55

52 Developing Protective Systems At University of California, Berkeley 52 of 55

53 Composite Shear Walls Can Be Used Around Stairwells to Protect Egress Routes Relatively Thin Steel Plate Welded to Steel Structure Steel Plate Resists the Pressure by Membrane Action. Components of the Proposed Wall Lightly Reinforced, Lightweight Concrete Panel Connected to Steel Plate Concrete Panel Bent and Damaged. Membrane Action of Steel Plate Behind Concrete Panel 53 of 55

54 Composite Shear Walls Can Be Used Around Stairwells to Protect Egress Routes Copyright 2001 Abolhassan ASTANEH-ASL 54 of 55 Research Data on Fire Resistance Can be Useful

55 Wish you were here Concluding Remarks: We need to undertake a scientific study of this threat and find out how vulnerable our buildings are. Then through sustained research and development programs respond to this threat and save the lives of people who can become the victims of this type of attack. We owe it to the memory of those who lost their lives during the 9/11 barbaric attacks. 55 of 55