Real-time Hybrid Fire Simulation of a Steel Moment-Resisting Frame under Post-Earthquake Fire

Post-earthquake-fires (PEF) are cascading extreme events in which structures burdened by seismic damage undergo elevated temperatures. One major problem in investigating PEFs is that experimental tests are costly, and therefore, are rarely conducted. On the other hand, numerical frameworks often disregard the disruptive effects of earthquake on the structure prior to its exposure to fire. To overcome this limitation, this paper presents a virtual version of a Real-Time Hybrid Fire Simulation (vRTHFS) on a benchmark moment-resisting steel frame in order to assess structural behavior during fire with existing earthquake damage. First, the structure is divided into numerical (NS) and virtual-physical substructure (vPS). The frame is subjected to ground excitation. Then, the vPS is exposed to elevated temperatures to bring the seismic damage into to the fire phase. The results indicate that the damage caused by a typical earthquake can reduce the axial load-bearing capacity of members significantly. In addition, the structure may undergo larger deformations under similar forces, resulting in the earlier appearance of instability. The vHFT conducted in this study is the first step toward experimental implementation of RTHFS while accounting for the effect of existing earthquake damage. It also indicates that neglecting residual seismic damage at critical regions in a structure prior to its exposure to fire, may result in overestimating structural capacity during fire.