Seismic Performance Evaluation of Mid-Rise Concrete Buildings Equipped with Lead Rubber Bearings Using Fragility Curves

<p>This study evaluates the seismic performance of mid-rise concrete moment-resisting frames (MRFs) equipped with lead rubber bearings (LRBs) using fragility curves. Two concrete buildings (8- and 12-story) were designed with and without LRBs in SAP software. Critical sections and stress ratios of structural members were extracted, and a representative 2D frame was modeled in OpenSees. Incremental Dynamic Analysis (IDA) was performed using 10 ground motion records, and fragility curves were derived based on inter-story drift ratios. Key findings include:<br>• The LRB system significantly increased the structural period, with amplification factors of 2.22 and 2.17 for the 8- and 12-story buildings, respectively.<br>• LRBs reduced inter-story drift by 14.3% (8-story) and 18.5% (12-story), enhancing seismic stability.<br>• Structures with LRBs tolerated higher peak ground acceleration (PGA) before reaching failure thresholds.<br>• The probability of earthquake-induced damage decreased by 11.8% (8-story) and 25.75% (12-story), indicating superior LRB effectiveness in taller buildings.<br>These results highlight LRBs’ potential to mitigate seismic risk in mid-rise concrete structures, particularly in high-rise configurations.</p>