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Mitigating of Progressive Collapse In 12/13/2017 Presenters Ahmed Khalil, Ph.D., P.E. Ayman Elfouly, P.E. • Structural Consultant • Structural Consultant • Applied Science International, LLC • Applied Science International, LLC Mitigating of Progressive Collapse in Structures • Member of SEI/ASCE • Member of SEI/ASCE • • Day 2 - 7 Hour Course Member of Disproportionate Member of Blast, Shock, & Impact Collapse Mitigation of Building Committee Ahmed Khalil, Ph.D., P.E. [email protected] Ayman El Fouly, P.E. [email protected] Structures Standards www.appliedscienceint.com │ www.extremeloading.com • Member of Disproportionate Collapse Technical Committee ©2006-17 Applied Science International, LLC ©2006-17 Applied Science International, LLC Morning Outline What is progressive collapse? 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 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC ©2006-17 Applied Science International, LLC Definition of Progressive Collapse Definition of Progressive Collapse Continued • Term is debated with respect to specific historical events • British Standards, Eurocode and ASCE 7, use term “disproportionate”: • Was the collapse of Oklahoma City Federal Building progressive incident? • 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” • Was the collapse of WTC towers progressive collapse? • Eurocode 1 Part 1-7 General Actions: “a structure shall be designed and executed in such • Other terms used to address the same phenomenon a way it will not be damaged by events like fire, explosion, impact, or consequences of • Disproportionate collapse human errors, to an extent disproportionate to the original cause” • Widespread collapse • 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC 1 12/13/2017 Definition of Progressive Collapse Continued Definition of Progressive Collapse Continued • NBC of Canada uses term “widespread ”: “A collapse that is triggered by localized damage that can’t be contained and • NBC of Canada Sec. 4.1.1.3 (1) “buildings …. Shall be designed to have sufficient leads to a chain of failures resulting in a partial or total structural collapse, structural capacity and structural integrity …” where the final damage is disproportionate to the local damage of the triggering event” • “structural integrity is defined as the ability of the structure to absorb local failure without widespread collapse” • 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC Why Are Code Provisions for PC Necessary? Definitions of Related Terms • Is it because of recent terrorist incidents? • Deformation-Controlled Action: A deformation-controlled action provides a resistance that is proportional to the imposed deformation until the peak • Older structures were able to resist some extreme loads due strength is reached, after which the resistance remains at a significant level, as to the inherent strength, continuity, and redundancy in its the deformation increases. 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC Definitions of Related Terms Definitions of Related Terms • Force-Controlled Action: A force-controlled action provides a resistance that is • Yield Rotation: The yield rotation θy corresponds to the flexural rotation at proportional to the imposed deformation until the peak strength is reached, which the extreme fibers of the structural elements reach their yield capacity after which the resistance drops to zero. 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC 2 12/13/2017 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 Historic Progressive Collapse Case Studies Mitigating of Progressive Collapse in Structures - 7 Hour Course DoD UFC 4-023-03, 2005, “Design of Buildings to Resist Progressive Collapse” Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC 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. Ronan Point • Explosion was small and pressure less than 10 psi • Kitchen and living room walls would fail at a pressure ~ 11.7 kPa. 1968 • 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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC 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 A.P. Murrah Federal Ronan Point Apartment Tower,” Forensic Engineering: Proceedings of the Third Congress, pp. 190 – 200, Bosela, Paul A., Delatte, Norbert J., and Rens, Building 1995 Kevin L., Editors, ASCE, October 19 – 21, 2003. Alfred P. Murrah Federal Building, Oklahoma City, Oklahoma (office facility for U.S. government). • McGuire W. The Why of General Structural Integrity, “,” Engineering Truck bomb detonated in front of its north side. Foundation Conference, Structural Failures II. Palm Coast, Florida, December 4000 pounds of explosives close to central supporting column 1987. Extensive structural damage to building Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC 3 12/13/2017 A.P. Murrah Building: Damage 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. [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 Day 2 - 7 Hour Course ©2006-17 Applied Science International, LLC Extreme Loading® Technology 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, Illinois, December 2001, Vol. 46, No. 12, pp. 29-30. ©2006-17 Applied Science International, LLC Day 2 - 7 Hour Course ©2006-17
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