跨越地裂缝RC框架结构钢支撑加固方法研究

Reinforcement method with steel supports for RC frame structure acrossing ground fissures

为了寻求高烈度地区跨越地裂缝结构合理的加固措施,以西安f_(4)地裂缝为研究背景,结合工程实例,按照刚度比原则对跨越地裂缝RC(reinforced concrete)框架结构布置钢支撑。通过振动台试验和有限元数值模拟,分析了结构的破坏形态和不同工况下支撑的应变反应,并从顶层加速度、层间位移和楼层剪力等方面对加固前后两种模型的抗震性能进行对比分析。研究结果表明,按照刚度比原则确定跨越地裂缝RC框架结构的支撑布置方式是可行的。钢支撑在结构破坏前屈服,耗散地震能量,降低结构损伤,有效提高了结构的抗震性能。同时,支撑最好在结构的上盘区域和下盘区域对称布置,可以提高结构的整体刚度,抵抗地裂缝场地的上、下盘效应。此外,钢支撑会对与其相连的RC框架柱产生附加轴力,因此为保证柱的延性要求,需要对加固后的框架柱进行轴压比验算。该研究成果可为该类跨越地裂缝结构的加固提供参考。

Here,to seek reasonable reinforcement measures for structures crossing ground fissures in high intensity areas,taking Xi’an f_(4) ground fissures as the study background,combined with engineering actual examples,steel supports were arranged for a reinforced concrete(RC)frame structure crossing ground fissures according to the principle of stiffness ratio.Through shaking table tests and finite element numerical simulation,failure mode of this structure and strain responses of supports under different working conditions were analyzed,and aseismic performances of the two models before and after reinforcement were analyzed contrastively from aspects of top-floor acceleration,inter-floor displacement and floor shear force.The results showed that it is feasible to determine support arrangement layout of RC frame structure crossing ground cracks according to the principle of stiffness ratio;steel supports yield before structure failure,they dissipate seismic energy,reduce structure damage and effectively improve aseismic performance of the structure;supports are preferably symmetrically arranged in hanging wall area and footwall area of the structure to improve the overall stiffness of the structure,and resist hanging wall and footwall effects of the ground crack site;steel supports can produce additional axial force on the RC frame columns connected with it;to ensure the ductility requirements of columns,it is necessary to check the axial compression ratio of reinforced frame columns;the study results can provide a reference for reinforcement of this kind of structure crossing ground fissures.