Seismic Fragility Analysis of a Water Storage Structure

Probabilistic seismic risk assessment (PSRA) of a structure is essential to identify the seismic vulnerability of structural members associated with the different stages of damage. Seismic fragility evaluation is a widely accepted approach to develop seismic vulnerability information for the structures. The present paper is concerned with the seismic response and fragility evaluation of a water storage structure. Seismic analysis has been carried out considering the hydrodynamic effects of the contained water. For seismic fragility evaluation, the various parameters that could affect the seismic structural response have been identified as material strength of concrete, structural damping available within the structure, and the normalized ground motion response spectral shape. Based on this limited case study, the seismic fragility of the structure is developed as families of conditional probability curves plotted as a function of peak ground acceleration at the location of interest. The paper presents the method adopted for the seismic fragility evaluation that incorporates the various randomness and uncertainty associated with the parameters under consideration. Typical results of fragility have been presented for different stresses, i.e., corresponding to the different modes of failure. The results of the fragility study show that the seismic structural response at the location of interest is quite sensitive to the randomness and uncertainty associated with the variable parameters considered in the present study. These results will be useful for PSRA studies.