偏心隔震结构扭转效应的影响因素分析

Research on the Effect of Torsional Response of Base-isolated Buildings

基于串联刚片模型,推导了隔震结构的振动方程,通过对一个典型的偏心隔震结构进行数值分析,讨论了上部结构的质量偏心、上部结构偏心率、隔震层偏心率和隔震层的水平刚度对扭转效应的影响。结果发现,隔震层刚度对隔震结构扭转效应起主要作用,隔震层刚度越大,扭转效应越明显;质量偏心率和隔震层偏心率的增大都会增大隔震结构的扭转效应,但增幅不超过30%;随上部结构偏心率的增加,层内力比逐渐增大,减震效果变差。因此,实际应用中应该控制偏心率不大于0.6,否则,应以层扭矩比而不是层剪力比作为减震效果的依据;对于隔震结构,建议用位移比作为扭转不规则的判断条件,即当位移比超过1.2时,认为隔震结构为扭转不规则。

The rigid layers in series models is obtained as the asymmetric isolated buildings and the torsional response of an actual asymmetric isolated building is investigated,with the objective of studying the influence：the mass eccentricity in the superstructures;the stiffness eccentricity in the superstructure;eccentricity in the isolation system;the stiffness of the isolation system.The following conclusions have been attained,Torsional amplification can be significantly depending on the stiffness of the isolation system.Torsional response is increased due to the effect of mass eccentricity in the superstructures and eccentricity in the isolation system.It should not exceed 30%.The effect of isolation is reduced with the stiffness eccentricity in the superstructure increasing.It is concluded from the study that the ratio of stiffness eccentricity is less than 0.6.Proposed guideline define that a base-isolated building has torsional irregularity when the ratio of displacement is more than 1.2.