Fragility-based seismic performance assessment of steel braced and moment resisting frames

Abstract

The study assesses the fragility assessment of Concentrically Braced Frames (CBF), Eccentrically Braced Frames (EBF), and Special Moment Resisting Frames (SMRF) using Nonlinear Static Pushover Analysis (NSPA). A comparative evaluation of Performance-Based Plastic Design (PBPD) and Force-Based Design (FBD) is conducted using fragility curves developed through the Capacity Spectrum Method (CSM) to quantify exceedance probabilities across various damage states. Results indicate that PBPD significantly reduces exceedance probabilities in the Complete damage state, with reductions of 9.2% (3-storey), 6.6% (6-storey), 9.0% (9-storey), and 10.0% (12-storey) in CBF; 23.0%, 22.6%, 16.7%, and 11.3% in EBF; and 25.9%, 23.6%, 6.0%, and 0.0% in SMRF, respectively. Additionally, PBPD reduces structural weight, achieving reductions of 15.17% in SMRF, 7.24% in EBF, and 3.51% in CBF. Furthermore, PBPD enhances drift control, decreasing yield drift variations by up to 45% in CBF and 35% in EBF, ensuring more controlled inelastic deformations. Overall, PBPD enhances seismic resilience, optimizes material efficiency, and minimizes damage risks compared to FBD.