Aim. The introduction of the full paper reviews a number of papers in the open literature and then proposes our method that is, we believe, more effective, general and practical than existing ones. Section 1 explains our method of seismic fragility analysis; its core consists of: (1) we apply the RSM and use a second-order polynomial function, given in eq. (1), to supersede the conventional complex dynamic model; (2) we use the central composite design method to construct a series of experimental points of fewer numbers, while satisfying accuracy requirements for prediction; (3) we present the procedural steps for seismic fragility analysis, the flow chart of which is given in Fig. 1. Section 2 takes into consideration the seismic ground motion of a bridge and its uncertainties to establish its model. The core of section 3 consists of: (1) we use the ductility of a pier as an index to calculate the conditional probability through the Monte Carlo simulation; (2) we obtain the bridge seismic fragility curves by numerical methods; (3) each of the response surface models exhibits high correlation between the actual responses and those that are approximated by the corresponding metamodel. The seismic fragility analysis results, given in Fig. 6, show preliminarily that our method is more effective, general and practical and can be used to predict seismic disasters and protect common highway bridges against earthquakes.%文章考虑地震地面运动和结构本身的物理不确定性,以中心复合设计法建立地震动-桥梁结构试验样本对,对系统样本模型进行非线性时程分析,通过数值方法建立以柱端转角延性为输出的响应面模型,在此基础上采用蒙特卡罗模拟获得结构的易损性曲线.算例表明,所建立的高精度响应面模型可以替代需要进行复杂非线性计算的结构模型,且计算量少、结果可靠,有效地提高了易损性分析作为一种震害评估手段的时效性和前瞻性,具有实际工程应用价值.
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