多层屈曲约束斜撑钢框架抗震性能研究

Seismic Research on Multistory Buckling Restrained Braced Steel Frame

摘要:

为研究多层屈曲约束斜撑钢框架(buckling restrained braced frame, BRBF)的弹塑性动力性能，采用刚接与铰接两种形式的模型为研究对象，以屈曲约束斜撑（buckling restrained brace, BRB)水平力分担率平均值β和首层剪重比CB为主要研究参数，通过弹塑性动力二阶非线性分析，探讨了BRBF结构的抗震性能.结果表明：在设防烈度地震下最大层间位移各层分布较均匀；罕遇和特大地震下,刚接模型除首层和顶层外各层集中，铰接模型因柱脚铰接首层特别大，另外受第二振型影响中上层也较大.强震作用下，β≈30%时，结构以剪切变形为主，第一振型卓越；β≈60%时，第二振型参与；β≈90%时，第二振型卓越.结构基本周期一定时，β值大小不影响地震输入总能量；模型基本周期相近时，结构等效速度VE基本相等；同时，β值可从结构弹性基本周期以及地震波弹性体系能量谱中得到推算，再次验证了基于能量平衡抗震设计法的有效性.

关键词:屈曲约束斜撑水平力分担率平均值; 高阶振型; 构件需求性能; 能量设计法

Abstract:

To study the elasticplastic dynamic performance of multistory bucklingrestrained braced steel frame (BRBF) which modeled separately with rigid and pinned models, the bucklingrestrained brace (BRB) average horizontal force sharing ratio β and shearweight ratio CB were used as the main parameters, and the secondorder nonlinear elasticplastic dynamic analysis method was adopted. The research results are as follows: Maximum story drift distributes more evenly under the seismic fortification intensity, concentrates except for the first and top floor in the great or rare earthquake with the rigid model, focuses on the first floor particularly with the hinged column base from the pinned model, and additionally focuses on middle and upper layers affected by the second vibration mode. When β ≈30% under the great earthquake, the shear deformation dominates the structure and the first vibration mode is excellent; β≈60%, the second vibration mode participates in; β≈90%, the second vibration mode is remarkable. β value does not affect the seismic input energy when the fundamental period is set down, and the equivalent velocity VE is basically the same during the similar fundamental period; Meanwhile, VE values can be derived from elastic fundamental period and seismic wave energy spectra, which once again shows the effectiveness of seismic design based on energy balance method.

Key words:buckling restrained brace (BRB) average horizontal force sharing ratio; higher vibration mode; member performance requirement; seismic design based on energy balance method