Probabilistic seismic performance evaluation of the steel frame buildings controlled with lead rubber bearings (LRBs)

The probabilistic analysis could effectively apply the effects of uncertainty in the structural analysis, where fragility curves are a well-established technique for the probabilistic evaluation of the structural performance. Notably, incremental dynamic analysis (IDA) is one of the most common analytical methods for obtaining fragility curves. In this study, the statistical and probabilistic seismic performance of 3- and 9-story steel buildings are investigated under 22 pairs of far-fault records introduced in FEMA P695. The seismic performance of both uncontrolled and controlled buildings with LRB is studied using IDA. Then, a general mathematical equation corresponding to each structure will be determined for all damage states known as the probabilistic seismic demand model (PSDM) of the structures. Using this equation, the collapse fragility curve of the structures will be determined for both uncontrolled and controlled structures with LRB. To evaluate the possible impact of different levels of seismic intensities on the performance of the isolated structure, the collapse fragility curves for three different levels of intensities of the benchmark records are presented. According to the collapse fragility curves, in addition to the effect of different levels of seismic intensity on the seismic performance of the structure, it is possible to see the positive effect of the LRB in reducing the probability of collapse. Also, the collapse margin ratio (CMR) in the 3- and 9-story buildings has increased by 100% and 81%, respectively, which indicates the better performance of the LRB isolators in low-rise structures.