用于地下结构地震反应分析的改进反应加速度法

为考虑结构的存在对反应加速度法中地震输入荷载的影响，基于《城市轨道交通结构抗震设计规范》（GB 50909—2014）中的反应加速度法，提出将土-结构模型转换为自由场模型的等效方式进行地震反应分析。采用等效自由场进行地震输入荷载计算，近似地考虑了结构的存在对地震输入荷载的影响，以期提高反应加速度法的计算精度。使用有限元软件ABAQUS，采用改进前后反应加速度法对日本大开车站不同工况下的地震反应进行计算。研究结果表明，采用等效自由场计算的地震输入荷载有效提高了反应加速度法的计算精度。在验证等效方式有效性的基础上，分析等效模型宽度的选取对反应加速度法计算结果的影响，建议等效模型边界至结构侧边的距离取为1～3倍结构宽度。

An Improved Response Acceleration Method for Seismic Analysis of Underground Structures

In order to consider the influence of structure on the seismic input load in the response acceleration method (RAM), an equivalent method for transforming the soil-structure model into a free-field model is proposed based on the RAM in the Code for Seismic Design of Urban Rail Transit Structures (GB 50909—2014). The seismic input load calculated by the equivalent free-field approximately considers the influence of the structure on the seismic input load, and furtherly improves the calculation process of the RAM. The finite element software ABAQUS is used to calculate the RAM and the improvedRAM under the different working conditions of Daikai Station. The results show that the seismic input load calculated by the equivalent free field method effectively improves the calculation accuracy of the RAM. On the basis of verifying the validity of the equivalent method, the influence of the selection of the equivalent model width on the calculation results of the RAM is discussed. It is suggested that the distance from the boundary of the soil-structure model to the side of the structure is equivalent to 1～3 times the structure width.