基础摩擦滑移隔震结构起滑加速度研究EI北大核心CSCD

起滑条件是影响滑移隔震结构动力响应特性的重要参数,也是滑移隔震结构性能化设计研究的理论基础。采用两自由度模型模拟滑移隔震结构,基于动力时程分析方法,分析了隔震结构参数(包括自振周期、质量比和摩擦系数)和地震动参数(包括反应谱特征周期和近断层地震动脉冲)对隔震结构起滑加速度的影响。结果表明:结构参数比地震动参数对起滑加速度的影响更明显。隔震结构的起滑加速度-自振周期曲线分为下降、水平、上升和先上升后水平4段。所选地震动集激励下,当自振周期小于1.4 s时,相同自振周期结构的起滑加速度随质量比的增大而减小;大于7.8 s时,起滑加速度随质量比的增大而增大。起滑加速度随摩擦系数的增加而等比例增大。基于分析结果,采用分段拟合方法建立了起滑加速度计算公式,公式计算结果和多自由度结构算例的时程分析结果吻合良好。研究成果可为滑移隔震结构的起滑条件研究和结构设计提供参考。

A NUMERICAL STUDY ON SLIDING OCCURRENCE ACCELERATION FOR SLIDING BASE ISOLATION STRUCTURES

The occurrence condition of sliding is an important parameter for the dynamic response characteristics of the sliding base isolation structures, and it provides the theoretical basis to the performance based structural design of the sliding base isolation structures. A two-degree-of-freedom system model is adopted to simulate sliding base isolation structures. Base on the time history analysis method, the influence of various structural parameters (including natural period, mass ratio, and sliding friction coefficient) and ground motion parameters (including characteristic period of response spectrum and pulses of near-fault ground motion) on the sliding PGA are investigated. The results indicate that the structural parameters exhibit a stronger influence on the sliding PGA than that of the ground motion parameters. The sliding PGA versus natural period relationship curves of the isolated structures consisted of 4 segments, i.e., descend segment, horizontal segment, ascend segment, and ascend initially then keep horizontal segment. The sliding PGA decreases with increase in the mass ratio for the structures with natural periods smaller than 1.4 s, and increases with increase in the mass ratio for the structures with natural periods larger than 7.8 s subjected to the considered ground motion groups. The sliding PGA increases in an equal proportion with the increase of the sliding friction coefficient. An empirical expression to predict the sliding PGA is proposed using a piecewise linear fitting method. The calculated results of sliding PGA for the multi-degree-of-freedom structures using the proposed expression and time history analyses are in a good agreement. The results provide a basis for the following research on the sliding occurrence condition and the structure design of the sliding base isolation structures.