OPTIMIZING SEISMIC PARAMETERS OF DESIGN LATERAL FORCE PATTERN IN PERFORMANCE-BASED PLASTIC DESIGN OF SMR FRAMES WITH GENETIC PROGRAMMING

In this study, the investigation of maximum inelastic displacement demands in steel moment- resisting (SMR) frames designed using the Performance-Based Plastic Design (PBPD) method is conducted under both near-fault and far-fault earthquake records. The PBPD method utilizes a target drift and predetermined yield mechanism as the functional limit state. To accomplish this, ۶ steel moment frames having various heights were scaled using well-known sa(T۱)  method and, then, were analyzed by OPENSEES software. A total of ۲۲ far-fault records and ۹۰ near-fault records were compiled and employed for parametric nonlinear dynamic analysis. The near-fault records were classified into two categories: T۱/Tp≥۱  and T۱/Tp<۱ . The study aimed at investigate their impacts on the inter-story drift and the relative distribution of base shear along the height of the structure. The results revealed that the records with T۱/Tp≥۱   exerted the greatest influence on the drift demands of upper stories in all frames. Conversely, the near-fault records with T۱/Tp<۱  demonstrated the most significant impact on the lower stories of mid-rise frames. Additionally, the distribution of relative story shears was examined through genetic programming for optimum PBPD design of steel moment frame structures. As a result, a proposed relationship, denoted as b (seismic parameter for design lateral force distribution), was developed and optimized for both near-fault and far-fault records. This relationship depends on the fundamental period of vibration and the total height of the structure. The accuracy of the predicted model was assessed using R۲ , which confirmed the reliability of the proposed relationship.

کلیدواژه ها:

Performance-Based Plastic Design (PBPD) ، Genetic Programming ، Optimization ، Seismic Parameter for Design Lateral Force Distribution.