基于改进响应面法的公路简支梁桥地震易损性分析

针对典型公路简支梁桥提出了一种基于改进响应面方法的易损性模型建构流程。在充分考虑结构和材料等桥梁参数不确定性基础上，基于Plackett-Burman设计方法生成一系列试验样本。采用OpenSees软件进行非线性动力时程分析，比较输入参数对地震响应的贡献，筛选出影响桥梁地震响应的显著性参数；进一步针对显著性参数进行中心复合设计并设计出一系列桥梁样本，基于非线性时程分析结果，建立桥梁各构件在不同的地震动强度下的响应面模型，并采用蒙特卡罗抽样方法计算得到桥梁构件的易损性曲线。假定简支梁桥系统为串联系统，计算生成全桥的易损性曲线。针对相同的桥梁样本，以非线性增量动力分析法生成的易损性曲线为基准，对传统响应面法与改进响应面法计算得到的易损性结果进行比较。结果表明：改进的响应面方程可以高效地替代复杂的非线性时程分析，提高了地震易损性分析的计算效率；构建的易损性曲线能够在较大的地震动强度范围内确定桥梁的损伤构件，帮助桥梁管理部门制定相应的震后加固优先级决策，具有一定的工程应用价值。

SEISMIC VULNERABILITY ANALYSIS OF SIMPLY SUPPORTED HIGHWAY BRIDGES BASED ON AN IMPROVED RESPONSE SURFACE METHOD

A new procedure is proposed to derive the analytical fragility models of simply supported highway bridges based on an improved response-surface method. By considering of the uncertainties in the structural and material properties of the bridges, the bridge samples were obtained by Plackett-Burman design method. From the nonlinear time history analysis through the OpenSees software, several parameters that affect the seismic response of the bridge significantly were identified. From the bridge samples obtained by using the central composite design (CCD) method with the chosen optimal parameters focused on, response surface models under different PGA levels were established from the finite element models with respect to each component's response. The simply supported bridge system was assumed to be a series system and the fragility curve was obtained by Monte Carlo simulation method. From the same bridge samples, fragility curves generated by means of incremental dynamic analysis were used as a benchmark. The results of the traditional response surface method and the improved response surface method were compared to each other. It is found that the improved response surface function could efficiently replace the complex nonlinear time history analysis and improve the efficiency of the fragility analysis. These resulting fragility curves will assist the users to identify the vulnerable bridge components over a large seismic intensity range and aid the bridge management decision-making process to prioritize the seismic strengthening repairs. Therefore, it is comparatively valuable as a new procedure in relevant civil engineering applications.