余震持时特性对高烈度区渡槽动力响应的影响研究

Influences of Aftershock Duration Characteristics on Dynamic Response of Aqueduct in High-Intensity Area

主震发生后会在短时间内引发多次余震,长持时余震是否会对主震受损后的高烈度区渡槽结构造成额外损伤仍需探讨.以滇中引水工程某典型梁式渡槽为工程实例,建立渡槽-水-支座-支撑结构全耦合有限元模型.基于能量持时的定义,以设计反应谱为基础,从PEER强震数据库中选择长持时和短持时地震动记录来构造主、余震地震序列,对渡槽结构进行非线性动力分析;充分考虑主震作用后渡槽的初始损伤状态,提出了渡槽损伤评价指标,探讨了不同持时的余震对主震受损后渡槽结构动力响应的影响.结果表明:余震持时特性对主震受损渡槽的抗震性能有显著影响,长持时余震对主震受损后渡槽结构造成更严重的累积损伤,在渡槽动力响应分析中不容忽视.因此,在渡槽地震安全评估和抗震设计时,除需考虑余震的频谱特性和幅值外,还应重点考虑持时特性.

Since a mainshock will trigger multiple aftershocks over a short period of time,it is necessary to discuss whether the long-duration aftershocks will cause an extra damage to an aqueduct structure that has been damaged in the mainshock in a high-intensity area.In this paper,a typical beam aqueduct in the Central Yunnan Water Diversion Project is taken as an example,and a fully-coupled finite element model of aqueduct-water-support-bent structure is established.Based on the definition of energy duration and the design response spectrum,the long-duration and shortduration ground motion records are selected from the PEER strong earthquake database to construct mainshockaftershock seismic sequences,and the nonlinear dynamic analysis of the aqueduct structure is performed.With the full consideration of the initial damage state of the aqueduct after the mainshock,a damage evaluation index for the aqueduct is proposed,and the influences of aftershocks with different durations on the dynamic response of the aqueduct structure after the mainshock are discussed.Results show that the aftershock duration characteristics have a significant impact on the seismic performance of the aqueduct damaged after the mainshock,and the long-duration aftershocks will cause a more serious cumulative damage to the aqueduct structure after the mainshock,which should not be ignored in the dynamic response analysis of the aqueduct.Therefore,in the seismic safety assessment and seismic design of the aqueduct,besides the spectral characteristics and amplitude of aftershocks,their duration characteristics should also be taken into account in particular.