位移系数法中的C_1参数研究

Study on C_1 in Displacement Coefficient Method

C_1为 FEMA 273/356提出的位移系数法中考虑预期的最大弹塑性位移与弹性位移比值的一个参数,并在 FEMA 440中作了修正,此值与结构的延性降低系数和场地情况有关。提出了适合中国四类场地三种设计地震分组共12种情况的 C_1值。采用416条实际地震波作为输入,依据规范对场地的分类指标以及场地特征周期对地震波进行分类,考虑6种不同结构延性降低系数的情况,进行大样本数值分析,以 FEMA 440中提出的 C_1,的公式为基准对结果进行回归拟合,得出适合中国场地情况 C_1值计算公式。

The coefficient C1 in the displacement coefficient method of FEMA 273/356 is the modification factor to relate expected maximum inelastic displacements to displacements calculated for linear elastic response. This coefficient, which relates to the ductility decreased coefficient of the structure and site condition ,was modified in FEMA 440. In this paper, appropriate C1 was proposed for use in China. A total of 416 earthquake acceleration time histories recorded in China, which were classified based on the code and the characteristic site period, were used. Meanwhile, six different ductility decreased coefficients were considered,and based on the large number of samples, the equation of C1 was proposed based on the regression fitting.