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Disproportionate collapse is an extreme loading event requiring consideration of all available load paths within a structure. Current criteria quantify acceptable performance limits through the use of seismic documentation. For steel moment frame structures, specifically, ASCE Standard 41-06 is used to quantify a loss of moment resisting capacity in the beam-column connections. This currently serves as the performance limit for the disproportionate collapse analysis of steel moment frame structures. A case study is presented featuring the disproportionate collapse analysis of an existing 33-story steel moment frame building using the nonlinear dynamic finite element program, LS-DYNA. The limitations encountered using ASCE 41-06 performance limits for disproportionate collapse analysis are discussed and finite element modeling considerations are enumerated. Furthermore, recent research on the collapse performance of seismic steel moment frame connections supporting this case study's conclusions regarding the limitations of ASCE 41-06 for disproportionate collapse analysis is discussed and recommendations for further research are proposed.

<p>Since the events of September 11, 2001, there has been a growing awareness of the need to design structures for resistance to terrorist attack. Many of the fatalities and injuries associated with blast on structures are due to shrapnel produced by the blast. The long carbon fibre investigated in this program is one of very few feasible alternatives for providing this resistance to spalling for concrete buildings (in addition to improving other structural properties). The material is a waste product from the Aerospace industry and can be mixed directly into concrete without significant changes to the standard casting process. The material also has potential for use in seismic regions, but the present focus is on blast resistance (explosives) and impact resistance (crash barriers, impact resistant bridge piers).</p> <p>While the material can be used successfully “as is” in a straight replacement for standard concrete, the true benefits come by taking into account the material as a portion of the reinforcement.</p> <p>Reinforcement beyond that required results in more difficult placement of the fibre concrete, reduces spalling resistance in low cover situations, and increases cost. Specimens designed for blast resistance (by codes such as the TM5-1300) require extremely heavy reinforcement. This paper will summarize the computational modeling and large-scale blast testing program used to develop design recommendations for long-carbon fibre concrete for wall and barrier applications.</p>