SEISMIC FRAGILITY ANALYSIS OF UNREINFORCED MASONRY STRUCTURES CONSIDERING PARAMETER UNCERTAINTIES

Due to the high dispersion of structural parameters and high nonlinearity of seismic responses, it is particularly necessary to consider the structural parameter uncertainties in seismic fragility analysis of unreinforced masonry structures. Taking four unreinforced masonry structures with different storeys as the research object and the equivalent frame finite element models are established in OpenSees. The incremental dynamic analysis and the FOSM method are employed to investigate the impact of the uncertainties of ground motion and structural parameters on seismic fragility analysis. The analysis results indicate that the uncertainties of ground motion and structural parameters should be considered in the seismic fragility analysis of unreinforced masonry structures and the impact is greater when the structural seismic damage is severer. The impact of structural parameter uncertainty is almost the same as that of ground motion uncertainty. Compared with ground motion uncertainty, the impact of structural parameter uncertainty becomes even more obvious with the smaller number of structure storeys. The changing of median value of seismic fragility was investigated through sensitivity analysis, and it was found that the influence of structural damping ratio is 4 times that of other single parameter, demonstrating the highest sensitivity of seismic response to structural damping ratio.