BRB在既有单跨多层混凝土框架结构加固设计中的应用

Application of BRB in strengthening design of existing single span multi-storey reinforced concrete frame structures

采用防屈曲支撑对某单跨多层混凝土框架结构进行了抗震加固,使用有限元分析软件SAP 2000对结构加固效果进行了验证,且对结构在多遇地震作用下的抗震性能进行了分析,对比了加固前后结构的侧向位移、层间位移角及周期比。以OpenSees有限元分析软件建立了加固框架的有限元分析模型,从美国太平洋工程研究中心(PEER)选取10条地震动记录调至设防烈度和罕遇地震水平进行了动力时程分析。结果表明:对单跨多层混凝土框架结构采用防屈曲支撑进行抗震加固,可以明显提高结构的刚度、耗能能力,有效地减小结构动力响应,降低震后加固修复费用;布置BRB后明显改善了结构抗震性能,在设防烈度水平可以有效避免结构构件的轻微损伤及非结构构件的破坏,而在罕遇地震水平不仅避免了结构层间位移角超过弹塑性层间位移角限值2.0%,而且有效避免了结构的薄弱层破坏。

The buckling restrained braces(BRB)were used to strengthen seismically a single span multi-storey concrete frame structure.The strengthening effect was verified via the numerical analysis using finite element analysis software SAP2000,in which these indexed,such as lateral displacement,storey drift ratio and ratio of translation period and torsion period,were compared.Besides,the numerical model of the strengthened frame was built using the finite element software OpenSees to perform nonlinear dynamic analysis,in which ten suits of ground motions were selected from PEER and scaled to two seismic hazard levels,the seismic precautronary intensity earthquake and rare earthquake,as the ground motion excitation.The results indicate that the stiffness,energy dissipating capacity of structures are enhanced significantly,and dynamic response is decreased due to the arrangement of BRB as well as the repair costs after earthquake are reduced obviously.In comparison to the original structure,the seismic performance of the structure employed with BRB is improved obviously.The damage of nonstructural components and slight damage of structural components can be avoided under design basis earthquake.Moreover,through comparison with the results of the frame without BRB,it is found that the BRB are effective in decreasing overall drift demands so as to less than the threshold of 2.0%at the rare earthquake level,as well as mitigating detrimental soft storey damage observed in the original frame.