叠层橡胶支座竖向刚度退化对隔震结构的影响

Influence of vertical stiffness degradation of laminated rubber bearings on isolated structures

摘要:

隔震结构在地震作用下,叠层橡胶支座竖向刚度随剪切变形增加而不断退化,对整体隔震结构产生的影响尚不明确.为此,通过ABAQUS建立不同层数、层高、柱距的隔震框架结构,支座本构采用修正的双弹簧模型结果.通过ABAQUS用户单元子程序UEL,采用FORTRAN语言编写了能够考虑支座竖向刚度退化的支座单元程序；输入实际罕遇地震波,对结构进行弹塑性动力时程分析,研究支座竖向刚度退化对结构地震响应的影响.结果表明:支座竖向刚度退化对结构柱底剪力、轴力、弯矩及梁弯矩有一定影响,地震响应放大系数结果为1.1~1.3；支座竖向刚度退化对支座剪切变形及上部结构层间位移影响较小.研究结果可为今后进行罕遇地震作用下隔震结构的计算分析提供重要依据.

Abstract:

The vertical stiffness of laminated rubber bearings degrades with the increase of shear deformation under earthquake, and the influence on the isolated structure is not yet clear. Therefore, several isolated frame structure models with different floor numbers, floor heights, and column distances were established by ABAQUS. The modified two-spring model was adopted for the bearings, and a program considering the vertical stiffness degradation of bearings was developed by FORTRAN language based on the model and user subroutine interface UEL in ABAQUS. Then rare earthquakes were input and the elastic-plastic dynamic time history analyses were carried out. Influences of vertical stiffness degradation on structural response were studied. Results show that the vertical stiffness degradation of bearings had certain effects on the shear force, axial force, bending moment of column, and bending moment of beam, and the seismic response amplification factors ranged from 1.1 to 1.3. The vertical stiffness degradation of bearings had no obvious influence on the shear deformation of the bearings or the interlayer displacement of the structures. This study provides a reference for future calculation and analysis of isolated structures under rare earthquakes.