带竖向连杆的偏心支撑钢框架结构抗震性能评估

Seismic performance evaluation of tied braced steel frames

带竖向连杆的偏心支撑钢框架结构通过在耗能梁两端增设竖向连杆,以改善传统偏心支撑钢框架结构中耗能梁非弹性变形不均匀的问题。本文分别根据考虑高阶振型影响的设计方法和原有设计方法,设计了带竖向连杆的偏心支撑钢框架算例,并增加传统K形偏心支撑钢框架结构对比算例,通过增量动力分析和易损性分析,从结构的破坏状态概率、易损性指数和抗倒塌储备系数三个方面对比结构的抗震性能。结果表明,3种结构均可满足我国抗震规范中“小震不坏”“中震可修”和“大震不倒”的抗震设计要求。由于竖向连杆的变形调节作用,带竖向连杆的偏心支撑钢框架结构出现软弱层的概率更低,其发生较重程度损伤的概率也更低,具有更好的抗倒塌性能。在地震动强度较大时,考虑高阶振型影响的设计方法设计的带竖向连杆的偏心支撑钢框架结构整体参与耗能,各层耗能梁塑性发展更加均匀,抗震性能更好。

The tied braced frames(TBFs)were developed to achieve uniform inelastic deformation in the eccentrically braced steel frames(EBFs)by connecting links across the entire frame height with tie members.In this paper,the TBFs were designed by the method considering higher mode effects and the existing design method,respectively.The traditional K⁃EBFs were also established as contrast examples.Through the incremental dynamic analysis and fragility analysis,the seismic performance of the structures was compared by the exceedance probability of the damage state,vulnerability index,and collapse margin ratio.The results show that the TBFs and K⁃EBFs could meet the seismic design requirements of"no damage under frequent earthquake,repairable under earthquake of seismic precautionary intensity,and no collapse under rare earthquake".Due to the deformation compatibility of the ties,the TBFs can reduce the occurrence of weak stories,the exceedance probabilities of the extensive and collapse of the TBFs were less than the K⁃EBFs,and their collapse⁃resistant performance were also better.When the ground motion intensity is large,the TBFs designed by the method considering higher mode effects exhibit better seismic performance because of their more uniform plastic energy dissipation of the links.