多地震动作用下地下结构Pushover分析法研究

Pushover Analysis Method of Underground Structures Subjected to Multiple Earthquake Records

求解多地震动作用下结构响应均值与标准差是地震易损性分析的基础工作。在地下结构Pushover分析法的基础上,提出间接计算结构在多地震动作用下均值响应的求解方法,即间接求解法(Indirectly Solution Average,ISA)。该方法以多地震动作用下自由场响应均值为目标位移,采用倒三角荷载分布模式,经1次Pushover分析得到结构响应均值。采用ISA计算得到不同地震动强度(调幅12个强度等级)下地铁车站结构层间位移响应均值与标准差。将ISA计算结果与先进行地下结构Pushover分析,然后求取响应均值与标准差的直接求解法计算结果进行比较,可知2种方法得到的结构层间位移响应均值误差<2%,标准差误差基本<10%,验证了ISA计算精度,可为地下结构基于性能的抗震设计概率地震需求模型计算提供快速分析方法。

The computed average and standard deviation of the structural seismic response subjected multiple ground motion records is significant for the seismic vulnerability analysis.Based on the Pushover method of underground structures,this paper proposes a solution method(ISA)to indirectly calculate the average response of structure as it is subjected to multiple ground motion.The ISA method takes the average value of the free field response as the target displacement under the excitation of multiple ground motion records,and uses the inverted triangular load distribution model to calculate the structural average response employing one time Pushover analysis.Based on the ABAQUS software platform,the ISA method is used to calculate the average and standard deviation of the inter-story displacement of the subway station structure under the excitation of 48 ground motion records with 12 levels intensity of ground motion.By comparing with the results obtained from the Pushover analysis conducting the ground motion records one by one,the maximum value of the average error of the inter-story displacement is only 2%,and the standard deviation error is basically less than 10%,which verifies the calculation accuracy of the proposed ISA method.The above conclusions can provide a fast numerical analysis method to establish the probabilistic seismic demand model for performance-based seismic design of underground structures.