多层双向偏心框架结构弹塑性阶段扭平频率比分析

Inelastic Analysis of Uncoupled Torsion to Lateral Frequency Ratio of Two-Way Asymmetrical Multistorey Frame Structures

为了探讨多层双向偏心结构在弹塑性阶段平扭耦联变化规律,建立了带有双向抗侧力构件的多层双向偏心结构空间简化剪切模型.利用MATLAB编程和非线性静力分析方法探讨了3层双向均匀偏心框架结构在整个加载过程中的结构频率变化规律.结合由非线性静力分析得到的结构等效层恢复力模型,展开了多层双向偏心结构前3阶频率随扭平频率比和偏心率从弹性阶段到弹塑性阶段整个过程中的参数分析.分析结果表明:弹塑性阶段平扭耦联参数变化规律明显不同于弹性阶段;结构弹塑性发展的不同程度对频率随参数的变化规律有明显影响;结构弹塑性的发展削弱了扭平频率比和偏心率对频率的影响.

The simplified spatial shear model of bidirectional asymmetric multistorey dual lateral load-resisting members was proposed to study the lateral-torsional coupling inelastic behaviour of two-way asymmetric multistorey structures.Based on the MATLAB software and nonlinear static analysis,the variation of natural frequencies of two-way regularly asymmetrical three-storey frame structures in the whole loading process was investigated.Combined with the equivalent storey restoring-force model obtained from nonlinear static analysis,the parametric analyses of the system were carried out to study the effects of the uncoupled torsion to lateral frequency ratio and the eccentricity on the first three order frequencies.The whole loading process from elastic to inelastic was considered.The analysis results show that the lateral-torsional coupling behaviour in inelastic analysis is obviously different from that in elastic analysis;moreover,different extent of structure plasticity has a vital role in the variation of frequencies with parameters;the effects of parameters on frequencies can be reduced by the development of structure plasticity.