考虑参数不确定性的无筋砌体结构地震易损性分析

SEISMIC FRAGILITY ANALYSIS OF UNREINFORCED MASONRY STRUCTURES CONSIDERING PARAMETER UNCERTAINTIES

鉴于无筋砌体结构参数的高离散性及其地震响应的强非线性,在地震易损性分析中考虑其结构参数的不确定性显得尤为必要。以 4 幢不同层数的无筋砌体结构为研究对象,在 OpenSees 中建立等效框架有限元模型,采用增量动力法和一次二阶矩法考察了地震动及结构参数不确定性对其地震易损性的影响。分析结果表明:在无筋砌体结构的地震易损性分析中需考虑地震动和结构参数的不确定性影响,且结构地震破坏程度越高这种影响程度越大;结构参数的不确定性影响程度与地震动的影响程度相当;结构参数不确定性相比于地震动不确定性的影响随着结构层数的降低而变得更为明显;敏感性分析表明,结构阻尼比变化对易损性曲线地震强度中位值的影响可达到其他单个参数的 4 倍,其敏感性最高。

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.