Seismic reliability analysis of flat-plate structures

This paper presents an extension of the reliability analysis method for a plane frame structure to a flat-plate structure. The flat-plate structure is modelled as a frame structure by using the effective beam approach proposed by Moehle and Diebold. The condensation technique in TABS77 is further utilized to transform the frame structure into a stick model. The earthquake ground acceleration is represented by a segment of stationary Gaussian random process with mean zero and a Kanai-Tajimi power spectrum. The power spectrum together with the dynamic characteristics of structure is utilized in the random vibration analysis to derive the probabilistic structural response. The limit analysis procedure proposed by Aoyama is modified to determine the failure mechanism and the corresponding storey shear capacity of the flat-plate structure. The reliability of the structure is measured in terms of the largest storey limit state probability. The fragility curve of the structure is generated by evaluating the limit state probabilities at various levels of peak ground acceleration. From the hazard curve for a site and the fragility curve for a structure, the annual limit state probability of the structure can also be evaluated. A five-storey flat-plate structure assumed to be located in New York City is used to illustrate the reliability analysis method.