Probabilistic fragility analysis parameterized by fundamental response quantities

Analytical probabilistic fragility studies require extensive computer simulations to account for the randomness in both input motion and response characteristics. In this study, an approach whereby a set of fragility relationships with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility is presented. An exact solution for a generalized single degree of freedom system is developed and employed to construct a Response Database of coefficients describing commonly used log-normal fragility relationships. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility relationships for various limit states can be constructed without recourse to further simulation. The uncertainty associated with modeling simplifications is quantified by conducting comparisons between the proposed approach and detailed multi-degree of freedom (MDOF) systems. Application examples are given to demonstrate the efficiency of the proposed approach.