Performance Assessment of Steel Moment-Resisting Frame Structures Using Fragility Methodology

Abstract

This paper presents a probabilistic study using the fragility function method for the performance assessment of two 1/6-scale, single-bay, three- and eight-story steel moment-resisting frame structures representing rigid and flexible framed structures, respectively. Considering the impact of the uncertainties in seismic loading and response of structures, the adopted fragility methodology is believed to provide a realistic and robust assessment of seismic performance and vulnerability of the structures. Fragility curves were developed by considering appropriate performance levels and using the response data from nonlinear time-history analyses of the structures in longitudinal and transverse directions with respective moment and shear connections. Results of the fragility analysis showed that inclusion of panel zone reinforcement in numerical simulation of the framed structures lowers the seismic vulnerability and probability of damage to the structures. The relatively lower seismic performances of the structures in the transverse direction with shear connections and lower lateral stiffness were demonstrated as well. Moreover, the eight-story structure was found to be more vulnerable to seismic loading and severe damages compared to the three-story structure. The adopted fragility method can serve as an effective tool for assessing the performance and safety levels of structures, and in decision making as well as financing for seismic protection.