单轴偏心基础隔震结构的振动台试验及理论分析

Shaking-Table Test and Theoretical Analysis of Uniaxial-Eccentricity Base-Isolated Structure

为准确把握单轴偏心隔震结构的动力学特性并建立相应的理论简化分析方法,文中对三层两跨基础隔震钢框架模型进行了不同偏心工况下的振动台试验,研究了结构扭转效应与偏心工况的关系,分析了隔震前后结构层间剪力、层间扭矩、层间转角以及不同偏心距下结构隔震层扭转角加速度和扭转角位移的变化规律.运用层单元模型建立了偏心隔震结构动力简化分析方程,对试验模型进行了理论分析.试验与分析表明:调整隔震层刚心使其与上部结构质心位置接近可显著降低偏心隔震结构扭转反应;所建简化分析方程能有效模拟偏心隔震结构的平扭耦联响应.

In order to reveal the dynamic characteristics of the uniaxial-eccentricity base-isolated structure and establish corresponding simplified method of theoretical analysis, a 3-story 2-span base-isolated steel frame model is investigated by means of the shaking-table tests under different eccentric conditions. Then, the relationship between the torsional effect of the structure and the eccentric condition is discussed. Meanwhile, at different eccentricities, not only the change laws of the shear force, torque and rotation angle between the structure floors before and after the isolation but also the change laws of the acceleration and displacement of the torsion angle of the isolated layer are analyzed. Moreover, based on the layer element model, the simplified dynamic equation of the eccentric isolated structure is established, and the test model is theoretically analyzed. The experimental and analytical results show that the torsional response of the structure can be significantly reduced by the adjustment of the centre of the stiffness of the isolated layer to the mass centre of the superstructure, and that the proposed simplified dynamic equation is capable of effectively stimulating the lateral-torsional coupling response.