Behavior of steel structures with soft story under post – earthquake fire

According to historical records, the risks of post-earthquake fire can sometimes be much more severe and more threatening than the dangers of earthquakes in the area. Also considering the type of materials used in buildings, steel structures are widely used throughout the world and are one of the best options available to other materials. Despite its greater advantages, steel is a vulnerable material against fire. Furthermore, according to irregularities in the buildings, which are mostly used for architectural and beauty reasons. The study of irregular buildings such as soft story in the ground floor with more height are more susceptible to earthquakes than regular buildings and its study will also be important under the post-earthquake fire. In this study, two types of structures conforming to the loading and details of the plan and the height of SAC 9 building in FEMA-355C are designed with ASCE7-10 Code that one of them is regular (without soft story) and the other is irregular in the first story (with soft story). Then, 2-D frame of the steel moment frame around both samples is modeled on ABAQUS and SAP softwares. And with simulating the earthquake, by non-linear static analysis in SAP software, and fire simulating in ABAQUS software, the effect of the frames has been investigated under the post-earthquake fire. Finally, it is observed, that regular frame in the first story have a shorter time of the resistance than irregular frame under the post-earthquake fire. Also, irregular frame changes from performance level of life safety to performance level of collapse prevention by the post-earthquake fire in some selected scenarios of fire.

Keywords:

Soft story , non-linear static analysis , post-earthquake fire , steel structure