The study of seismic performance and fragility function of i-section links

The component fragility function is a statistical distribution that indicates the conditional probability of incurring damage at a given value of the demand parameter. By constructing the fragility function of links, it is possible to quantitatively classify the damage degree after seismic action, clarify the corresponding repair methods, and conduct an in-depth analysis of the impact of key design parameters on fragility. To obtain the fragility functions of I-section links, 153 sets of quasi-static test data were collected, including 9 sets conducted by this study. The phenomenon of each damage state (slight, slightly moderate, moderate, and severe) and its corresponding repair methods were described. Using plastic rotation as the demand parameter, a set of fragility functions for I-section links was developed to estimate different damage states. The effects of normalized link length ( ρ ), flange width-thickness ratio ( b f /2t f ), web depth-thickness ratio ( h 0 /t w ), and ratio of stiffener spacing to link length ( d/e ) on the fragility functions were analyzed and discussed respectively. It was found that under the same damage state, the plastic rotation of the I-section links decreased with an increase in ρ and d/e . For different damage states, b f /2t f and h 0 /t w exerted varying degrees of influence on the plastic rotation, respectively. Corresponding to a 50% probability, the plastic rotation limit values for the four damage states were determined as 0.025, 0.055, 0.063, and 0.098, respectively. The fragility functions established in this paper can provide a theoretical basis for realizing the seismic performance-based design and evaluation at the I-section link component level.