两维地震激励下格构拱动力响应简化评估方法

Simplified Procedure for Seismic Response Analysis of the Latticed Arch Under Bi-Directional Earthquake Excitations

通过对振型位移响应进行合理的线性组合,给出了两维地震激励下格构拱结构的变形模式,基于该变形模式导出了推覆分析的荷载模式,采用该荷载模式对结构进行一次非线性推覆分析,建立了一种等效单自由度体系,通过对该等效单自由度体系进行时程分析,求得结构目标性能点,进而得到结构整体动力响应;在此基础上,通过对两维地震动输入进行适当简化,提出了格构拱在两维地震激励下动力响应的简化评估方法.采用简化方法对某大跨度柱承格构拱结构分别在硬土和软土场地一系列地震波两维分量激励下的动力响应进行分析,与时程法分析结果进行对比表明:简化方法计算的动力响应变化趋势与时程法基本一致,两向节点位移和单元最大应力平均误差分别为15.1%、12.5%和16.6%,但计算耗时仅约为时程法的25%.

The deformation pattern of the large-span latticed arch under the bi-directional earthquake excitation was predefined and expressed as the linear combination of displacements of the dominant vibration modes.Based on the load pattern derived from the deformation pattern,a nonlinear pushover analysis was carried out to establish an equivalent single degree of freedom(ESDF)system.Then,the responses of the ESDF system were solved by response history analysis method.Finally,the target point of the structure was found so that the seismic responses of the overall structure were obtained accordingly.Since the two components of ground motion inputs were transformed,a simplified procedure for seismic response analysis of the large-span latticed arch under bi-directional earthquake excitations was proposed.The seismic responses of a latticed arch model under a series of bi-directional earthquake waves in firm and soft sites were obtained by the simplified procedure.Compared with the results given by response history analysis,the nodal displacements and the extreme stress of elements are consistent in trends and distributions,with relative errors about 15.1%,12.5%and 16.6%respectively,and 25%computing consumption.