Progressive Collapse Resistance of Braced Steel Frames Exposed to Fire

OpenSees is an open-source, object-oriented software framework developed at UC Berekeley. The OpenSees framework has been recently extended to deal with structural behaviour under fire conditions. This paper summarizes the key work done for this extension and focuses on the application of the developed OpenSees to study the influence of fire scenarios and bracing system on the resistance of steel frames against fire-induced progressive collapse. Single- and multi-compartment fire scenarios are applied. Additional horizontal and vertical restraints are applied to the frame to simulate the braced steel frame. A parametric study is carried out to find the fire-induced progressive collapse mechanisms of steel frames under various fire scenarios and restraining conditions. The collapse mode of frames is in the form of lateral drift and downward collapse of frames. It is proved that these two collapse nodes can be resisted by applying lateral and vertical restraint on the frame, respectively. The combination of two restraints has a better resistance effect.