中文摘要：

桥梁系统地震易损性分析的关键是建立桥墩、支座等多个构件的联合概率分布函数。然而,由于构件地震需求之间的相关性,直接建立构件之间的联合概率分布函数较为困难。为此,引入Copula函数方法,将构件地震需求之间的相关性和各构件的边缘概率分布函数进行分离,从而简化了联合分布函数的建模过程。在桥墩、支座地震易损性的基础上,基于Copula联合概率分布函数,建立了桥梁系统的易损性曲线,并将其和一阶界限法及Monte Carlo方法的分析结果进行对比。结果表明：基于Copula函数得到的桥梁系统易损性在整个地震动强度范围内均位于一阶界限法的上、下界之间;和Monte Carlo方法相比,Copula函数方法不仅考虑了构件地震需求之间的非线性相关关系,而且避免了大量的数值抽样,使计算效率显著提高。

英文摘要：

The joint probability distribution function of piers and bearings plays a crucial role in the seismic vulnerability analysis of a bridge system, which is, however, very difficult to be established directly due to the correlations between the seismic demands of bridge components. Therefore, the copula function method is introduced to separate the correlation between each component from the marginal distribution function and consequently simplify the modeling process of a joint probability distribution function. Based on the fragility functions of pier and bearing as well as the joint distribution function derived by a copula function, the fragility curve of a bridge system is developed. Furthermore, the fragility curve is compared with those of the first-order bound method and Monte Carlo method. The results show that： the seismic vulnerability of a bridge system ranges within the upper and lower bound of the first-order bound method; compared with Monte Carlo method, the copula function method takes the non-linear relationships among the seismic demands of bridge components taken into account and avoids a lot of numerical samplings, which subsequently improves the computational efficiency significantly.