PROPOSAL OF FRAGILITY EVALUATION METHOD OF UNDERGROUND STRUCTURE CONSIDERING MULTI DAMAGE MODES

Abstract

 The objective is to propose the method to evaluate a fragility curve of an underground structure for multi damage modes, and first, fragility curves about flexural failure and shear failure are evaluated for a seawater pipe duct. Next a basic procedure to evaluate the fragility curve to combine the damage probability of both damage modes and evaluation cases are shown.

 When composite curves of two damage modes are compared, the 2063Gal which is Am of flexural failure is almost the same with the 2067Gal which is Am of shear failure which considered shear reinforcement, it is found that there is a possibility that two damage modes are generated simultaneously. Here, Am expresses a value of PGA where the damage probability becomes 50%. In addition, the damage probability of the structure obtained by the connection is larger than the value for each damage mode. Furthermore, it is thought that the risk for the individual damage mode becomes the underestimate.