Progressive Collapse Analysis of Steel Braced Frames

Abstract

This paper studies the behavior of concentrically braced frames (CBFs) and eccentrically braced frames (EBFs) under a progressive collapse scenario, by using the alternate load path method, recommended in progressive collapse guidelines. The model structure is a 10-story steel moment frame with five bays in each direction. The present study has investigated the CBF with two types of failure scenarios, each of which examines the effects of reducing the brace’s sections, and the EBF, including three types of failure scenarios, each of which investigates the effects of link beam length on structural capacity. Failure scenarios include the sudden removal of a column with one or more adjacent braces on the ground floor, which, for simplicity, is examined in a two-dimensional form in a perimeter bay of the building. The ability of the structure to absorb and withstand extra load after the sudden removal of the members in each of the states is examined, and their capacity and ductility are compared. According to the results, both EBF and CBF systems can withstand the progressive collapse. Moreover, in the CBF system, while the cross sections of braces decrease, the ductility of the CBF structure increases.