梁式桥抗震分析中等效单自由度模型的适用范围

摘要

将单柱式桥墩等效为单自由度体系进行计算,是抗震分析中常用的简化分析方法.研究了该简化分析方法在桥墩弹性、塑性响应两阶段的适用范围.首先,推导了基本振型质量参与系数的简化计算公式,以桥墩基本振型质量参与系数为等效程度评价指标,评价桥墩质量分布、墩高对等效程度的影响.其次,在桥墩响应的塑性阶段,验证了振型质量参与系数作为评价指标,在不同塑性程度下的适用性.研究结果可为选择恰当的单柱式桥墩抗震分析方法提供参考.%Applicability of the simplified method based on equivalent single-degree-of-freedom ( ESDOF) for single-column pier with uniform cross-section is investigated in this paper. Firstly, expressions to evaluate the modal participating mass ratio of pier fundamental mode were obtained and the modal participating mass ratio of pier' s fundamental mode was taken as an index to evaluate the accuracy of the simplified method. Using the proposed expressions, it was convenient to evaluate applicability of the simplified method with the height of pier and the ratio of distributed mass along the column to dumped mass at the top of pier. Finally, the index was verified in different nonlinear staged of piers.