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Progressive Collapse Design 12/20/2017 Mitigating of Progressive Collapse in Structures Day 2 - 7 Hour Course Ahmed Khalil, Ph.D., P.E. khalilaa@appliedscienceint.com Ayman El Fouly, P.E. elfouly@appliedscienceint.com www.appliedscienceint.com │ www.extremeloading.com ©2006‐17 Applied Science International, LLC Presenters Ahmed Khalil, Ph.D., P.E. Ayman Elfouly, P.E. • Structural Consultant • Structural Consultant • Applied Science International, LLC • Applied Science International, LLC • Member of SEI/ASCE • Member of SEI/ASCE • Member of Disproportionate • Member of Blast, Shock, & Impact Collapse Mitigation of Building Committee Structures Standards • Member of Disproportionate Collapse Technical Committee ©2006‐17 Applied Science International, LLC 1 12/20/2017 Morning Outline 1. Definition of Progressive Collapse 2. Progressive Collapse Historical Events & Evolution of Code Regulations 3. Historic Progressive Collapse Case Studies 4. Design Philosophy for Progressive Collapse Mitigation in Codes and Standards Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC What is progressive collapse? Europan Journal of Educational Studies 2(1), 2010 39 EARTHQUAKE EDUCATION IN CIVIL ENGINEERING DEPARTMENTS OF UNIVERSITIES OF TURKEY Mizan Doğan Department of Civil Engineering, Eskişehir Osmangazi University, TURKEY ©2006‐17 Applied Science International, LLC 2 12/20/2017 Definition of Progressive Collapse • Term is debated with respect to specific historical events • Was the collapse of Oklahoma City Federal Building progressive incident? • Was the collapse of WTC towers progressive collapse? • Other terms used to address the same phenomenon • Disproportionate collapse • Widespread collapse Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Definition of Progressive Collapse Continued • British Standards, Eurocode and ASCE 7, use term “disproportionate”: • BS “the building shall be constructed so that in the event of an accident the building will not suffer collapse to an extent disproportionate to the cause” • Eurocode 1 Part 1‐7 General Actions: “a structure shall be designed and executed in such a way it will not be damaged by events like fire, explosion, impact, or consequences of human errors, to an extent disproportionate to the original cause” • ASCE 7 Sec. 1.4 “buildings and other structures shall be designed to sustain local damage with the structural system as a whole remaining stable and not being damaged to an extent disproportionate to the original local damage” Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 3 12/20/2017 Definition of Progressive Collapse Continued • NBC of Canada uses term “widespread ”: • NBC of Canada Sec. 4.1.1.3 (1) “buildings …. Shall be designed to have sufficient structural capacity and structural integrity …” • “structural integrity is defined as the ability of the structure to absorb local failure without widespread collapse” Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Definition of Progressive Collapse Continued “A collapse that is triggered by localized damage that can’t be contained and leads to a chain of failures resulting in a partial or total structural collapse, where the final damage is disproportionate to the local damage of the triggering event” • Why collapse can’t be contained? • Answer: Lack of ‐ • Continuity of tension ties (even in compression members) • Redundancy of load path • Ductility Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 4 12/20/2017 Why Are Code Provisions for PC Necessary? • Is it because of recent terrorist incidents? • Older structures were able to resist some extreme loads due to the inherent strength, continuity, and redundancy in its structural systems. • Recent structures have used optimization and refinement techniques that reduce their margin of safety • Framing systems designed: • for ease of construction • have lower level of inherent continuity • have lower level of redundancy Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Definitions of Related Terms • Deformation‐Controlled Action: A deformation‐controlled action provides a resistance that is proportional to the imposed deformation until the peak strength is reached, after which the resistance remains at a significant level, as the deformation increases. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 5 12/20/2017 Definitions of Related Terms • Force‐Controlled Action: A force‐controlled action provides a resistance that is proportional to the imposed deformation until the peak strength is reached, after which the resistance drops to zero. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Definitions of Related Terms • Yield Rotation: The yield rotation θy corresponds to the flexural rotation at which the extreme fibers of the structural elements reach their yield capacity fy. DoD UFC 4-023-03, 2005, “Design of Buildings to Resist Progressive Collapse” Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 6 12/20/2017 Definitions of Related Terms • Plastic Rotation: The plastic rotation θp is the inelastic or non‐recoverable rotation that occurs after the yield rotation is reached and the entire cross section has yielded DoD UFC 4-023-03, 2005, “Design of Buildings to Resist Progressive Collapse” Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Historic Progressive Collapse Case Studies Mitigating of Progressive Collapse in Structures ‐ 7 Hour Course Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 7 12/20/2017 Ronan Point 1968 Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC Ronan Point: Lessons Learned • Ronan Point lacked the connection details necessary to effectively redistribute load. • Explosion was small and pressure less than 10 psi • Kitchen and living room walls would fail at a pressure ~ 11.7 kPa. • Exterior wall would fail at a pressure ~20.7 kPa (3 psi). Collapse was attributed to lack of structural integrity. • No alternate load path for redistribution of forces. • Strong winds and/or effects of a fire could have caused progressive collapse. • Building had been built with very poor workmanship. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 8 12/20/2017 Ronan Point: References • Pearson C., and Delatte N., 2005, The Ronan Point Apartment Tower Collapse and its Effect on Building Codes, J. Perf. Constr. Fac. Volume 19, Issue 2, pp. 172‐177. • HMSO, “Report of the inquiry in the Collapse of Flats at Ronan Point, Canning Town,” 1968. • Rouse C., and Delatte N., “Lessons from the Progressive Collapse of the Ronan Point Apartment Tower,” Forensic Engineering: Proceedings of the Third Congress, pp. 190 – 200, Bosela, Paul A., Delatte, Norbert J., and Rens, Kevin L., Editors, ASCE, October 19 – 21, 2003. • McGuire W. The Why of General Structural Integrity, “,” Engineering Foundation Conference, Structural Failures II. Palm Coast, Florida, December 1987. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC A.P. Murrah Federal Building 1995 Alfred P. Murrah Federal Building, Oklahoma City, Oklahoma (office facility for U.S. government). Truck bomb detonated in front of its north side. 4000 pounds of explosives close to central supporting column Extensive structural damage to building Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 9 12/20/2017 A.P. Murrah Building: Damage [69] STAROSSEK U., 2006, Progressive Collapse of Bridges—Aspects of Analysis and Design, Invited Lecture, International Symposium on Sea‐ Crossing Long‐Span Bridges, Mokpo, Korea, Feb. 15‐17. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC A.P. Murrah Building: Damage • Extent of Collapse • Destroyed due to blast • Columns G16, G20 and G24. • Subsequent collapse due to failed columns • Third floor transfer girders between G16 and G26. • All floors and roof panels bounded by column lines 12, 28, F and G. • Total Building Floor Area: 137,800 ft 2 • 4% (5,850 ft 2) destroyed by blast. • 42% (58,100 ft 2) destroyed by blast + progressive collapse. Day 2 ‐ 7 Hour Course ©2006‐17 Applied Science International, LLC 10 12/20/2017 Extreme Loading® Technology ©2006‐17 Applied Science International, LLC A.P. Murrah Building: References • Corley W. G., Mlakar P. F., Sozen M. A., and Thornton C. H. “The Oklahoma City Bombing: Summary and Recommendations for Multihazard Mitigation”, Journal of Performance of Constructed Facilities, 12(3), 1998, P 100‐112. • Corley W. G., Mlakar P. F., Sozen M. A., and Thornton C. H. “The Oklahoma City Bombing: Structural Details and Possible Mechanisms for the Murrah Building”, Journal of Performance of Constructed Facilities, 12(3), 1998, P 120‐136. • FEMA 277 “The Oklahoma City Bombing: Improving Building Performance Through Multi‐Hazard Mitigation,” Federal Emergency Management Agency and ASCE, August 1996. • Hinman E. E. and Hammond D. J. “Lessons from the Oklahoma City Bombing: Defensive Design Techniques.” 1997 ASCE Press. • Hinman, H. (1997). Lessons from the Oklahoma City Bombing: Defensive Design Techniques, ASCE, New York. • Corley, W. Gene; Sozen, Mete A.; Thornton, Charles H.; and Mlakar, Paul F., "The Oklahoma City Bombing: Improving Building Performance Through Multi‐Hazard Mitigation," FEMA‐277, Mitigation Directorate, August 1996, U.S. Government Printing Office, Washington, DC, 90 pp. • Corley, W. G., Smith, R.G., and Colarusso, L. J., “Structural integrity and the Oklahoma City bombing,” Concrete Construction, A Hanley‐Wood Publication, Addison,
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