基础隔震结构附加变化型调谐质量惯容阻尼器的优化设计研究

Optimum design of base-isolated structure equipped with variant tuned mass damper inerter

在强震作用下基础隔震结构的隔震层将发生非常大的水平变形。已有研究表明采用在基础隔震结构的隔震层附加变化型调谐质量阻尼器(VTMD)的混合控制策略能够有效降低隔震层的水平变形需求,然而该混合控制策略最大的缺陷在于需要很大的调谐质量。考虑到惯容装置具有明显的质量放大效应,本文提出将惯容装置(Inerter)与VTMD中的阻尼器并联,从而形成具有较小调谐质量的变化型调谐质量惯容阻尼器(VTMDI),并将其附加在基础隔震结构的隔震层,基于随机振动的分析框架开展了VTMDI参数的优化设计研究。研究表明直接将基础隔震结构的上部结构层间变形作为优化目标的传统优化策略并不经济有效。为此,本文提出了一种基于两步优化法的优化策略,该优化策略首先确保附加VTMDI的基础隔震结构相对于附加相同阻尼的基础隔震结构具有更优的控制效果;然后确保附加VTMDI的基础隔震结构的上部结构层间变形最小。通过动力时程分析结果表明:两种优化策略都能有效降低隔震层的水平变形和上部结构的层间变形,同时不会导致调谐质量出现过大的运动行程,基于两步优化法的优化策略更为经济有效。

Base-isolation system would undergo considerable great displacement subjected to strong earthquake.According to recent research progress,the hybrid control strategy combining variant tuned mass damper(VTMD)with base-isolation system has been proved to be effective in reducing such great displacement demand.However,large tuned mass is required to achieve better control performance,which may be difficult to realize in practical application.Employing the mass-amplification effect of the inerter device,a variant tuned mass damper inerter(VTMDI)is proposed in this study by inserting the inerter device in parallel with the dashpot in the VTMD and is attached to the isolation level in the base-isolated structure.Due to the stochastic nature of seismic ground motions,investigation into the optimum design of the VTMDI are conducted based on the framework of random vibration.It is demonstrated that the traditional optimization strategy,taking the inter-story drift of isolated superstructure as the optimization objective,is not cost-effective.Thereby,a novel optimization strategy consisting of two step optimization procedure is proposed.In this two-step optimization strategy,the optimization objective in the first step is taken as the control effect of the base-isolated structure equipped with the VTMDI compared with that of the corresponding base-isolated structure with the same dashpot,and then the optimization objective in the second step is to minimize the inter-story drift of isolated superstructure.And the dynamic time-history analyses show that both optimization strategies can effectively reduce the horizontal deformation in the isolation level and inter-story drift in the superstructure,and the excessive strokes of the tuned mass are also avoided.However,the two-step optimization strategy is more cost-effective than the traditional optimization strategy.