Seismic performance assessment of RC buildings under Turkey ground motions designed by Force Based Design and improved performance based plastic design method

Performance-Based Plastic Design (PBPD) is a widely used method for improving the seismic performance of structures by allowing controlled nonlinear behavior. The method is based on energy balance principles and a predefined target drift. However, its reliance on lateral load calculations often results in reduced strength of structural members, particularly in low- to medium-rise buildings where beam sections frequently fail to meet safe design requirements. This limitation raises concerns about the safety and reliability of PBPD-designed structures. To address this issue, an improved PBPD method is proposed by incorporating the minimum reinforcement criteria for beams as specified in the Indian design code. A 10-story reinforced concrete special moment-resisting frame was designed using the improved PBPD method and compared with a frame designed using the conventional force-based design approach. Nonlinear Pushover Analysis and Nonlinear Time History Analysis under strong Turkish ground motions were performed to evaluate the seismic performance of both designs. The results indicate that the improved PBPD method significantly enhances the seismic performance of the structure. The maximum considered earthquake level performance point of the PBPD frame lies within the Collapse Prevention range, while its overall drift ratio is 19.82% lower than that of the Force Based Design (FBD) frame. Incremental Dynamic Analysis further shows that only one ground motion exceeded the target drift of 0.02 for the improved PBPD frame. Additionally, fragility analysis demonstrates that the probability of complete failure is reduced to 17.2% for the PBPD frame, indicating superior robustness and reliability compared to the FBD frame.