近断层地震作用下基础隔震结构的振动分析

Vibration Analysis of Base-isolated Structure Due to the Near-fault Seismic Motivation

基础隔震技术在目前的结构分析和设计过程中,对于冲击性较强的近断层地震作用考虑较少,特别是对竖向分量的考虑。本文选取1999年台湾集集地震中,含有完整水平与竖向地震分量的近断层速度脉冲型记录与断层附近非脉冲型记录作为地震输入,分析了基础隔震结构在近断层水平—竖向地震分量共同作用下的动力响应以及隔震支座的受力状态。结果表明,脉冲型近断层地震波对中长周期隔震结构的影响较大,最大速度脉冲周期对基础隔震结构动力响应不是绝对控制性因素;近断层地震波竖向分量对基础隔震结构水平向的振动效应影响较小,对隔震支座受力的影响较大,可能导致隔震支座处于不安全的受拉状态,且明显大于非脉冲型地震波的影响。重视近断层地震作用竖向分量的影响可能会有效保证隔震支座的安全。

The base-isolated technology is a generally acknowledged measure to resist the earthquake action and reduce the loss of building structure.But the near-fault seismic action,impulsive strongly,is not taken into account usually,and the vertical component is less especially.Some earthquake acceleration records selected from Chi-Chi Earthquake in Taiwan,including horizontal and vertical components,are divided into two types,near-fault pulse and non-pulse.The structural responses and the stress of base-isolated supports are analyzed under the horizontal and vertical motivations of those records simultaneously.The results show that the maximum velocity-pulse period of the seismic records is the key factor,but it does not control the dynamic responses of base-isolated structures absolutely.And the impulsive near-fault earthquakes impact the medium or long-period base-isolated structures strongly.The seismic vertical component influences the horizontal responses of structures slightly.But base-isolated supports could be in the unsafe tension under the pulse near-fault earthquake motivation,and stronger apparently than under the non-pulse.Focusing on the vertical component of near-fault earthquake moderately during the analysis will guarantee the safety of base-isolated support effectively.