Macromodel-Based Simulation of Progressive Collapse: Steel Frame Structures

Abstract

Computationally efficient macromodels are developed for investigating the progressive collapse resistance of seismically designed steel moment frame buildings. The developed models are calibrated using detailed finite-element models of beam-column subassemblages and account for the most important physical phenomena associated with progressive collapse. The models are utilized to compare the collapse resistance of two-dimensional, ten-story steel moment frames designed for moderate and high seismic risk according to current design specifications and practices. The simulation results show that the frame designed for high seismic risk has somewhat better resistance to progressive collapse than the system designed for moderate seismic risk. The better performance is attributed to layout and system strength rather than the influence of improved ductile detailing. The alternate path method is shown to be useful for judging the ability of a system to absorb the loss of a critical member. However, it is pointed out that the method does not provide information about the reserve capacity of the system and so its results should be carefully evaluated.