Linear and Non-Linear Static Progressive Collapse Analysis of Steel Framed Buildings with I-Beams and Truss Beams

Progressive collapse is the collapse of a considerably large part of a structure as a result of failure of its relatively small part. After the progressive collapse (PC) of the Ronan Point apartment tower in England in 1968, prevention of progressive collapse became one of the challenges of structural engineers. Since then, researchers carried out many studies on progressive collapse. In addition, General Services Administration (GSA), Department of Defense (DoD), and Unified Facilities Criteria (UFC) developed guidelines for assessing and preventing progressive collapse. Furthermore, NIST (National Institute of Standards and Technology) has published a list of potential load hazards that might generate progressive collapse. This study used GSA guidelines to investigate the progressive collapse potential of an eight story steel framed building by using I-beams and trusses as floor beams. Linear and nonlinear static analysis were used to assess the potential of PC by using the general purpose computional analysis program ETABS. Structural members PC potential is assessed according to Demand Capacity Ratio (DCR) for linear static analysis and rotation for nonlinear static analysis. The results show that, after removing the columns for linear static analysis, floors with truss beams had DCR values less than the floor with I-beams. The results of nonlinear static analysis indicate that the floors with I-beams had greater rotation values than the floors with truss beams. As part of Alternative Path Method, new bracings introduced in the bay adjacent to the removed column to rehabilitate the buildings.