L形截面RC短柱核心区混凝土等效单轴本构关系研究

Equivalent Uniaxial Constitutive Relationship for Core Concrete of L-shaped RC Short Columns

L形截面柱的箍筋约束机理不同于其他形式截面柱,为建立其核心区混凝土等效单轴本构关系,基于已有的7个混凝土L形截面RC短柱轴心受压试验研究结果,通过合理假定,将异形柱截面核心区混凝土划分成若干区域,给出了有效横向约束应力的推导过程。采用建议的本构关系对相关试验的试件进行了荷载变形全过程分析,计算结果和试验结果吻合良好。完成了L形截面短柱不同参数(箍筋间距、箍筋直径、箍筋屈服强度、截面形式)对箍筋约束作用的影响规律研究。结果表明:箍筋间距、箍筋直径、箍筋屈服强度对轴向荷载-变形曲线影响较大,与未考虑箍筋约束作用的轴向荷载-变形曲线相比,其轴压承载力、峰值变形及应变延性均有不同程度的提高;截面形式对荷载变形曲线影响较小。

The confinement mechanism of stirrups in L-shaped columns is different from that in other section shaped columns.In order to construct the equivalent uniaxial constitutive relationship for core concrete of L-shaped columns,based on the experimental results of seven L-shaped RC short columns subjected to axial load and reasonable assumptions,the core concrete in L-shaped section was divided into several regions,and the analytic derivation of the effective transverse confined stress was provided.The load versus strain curves of the specimens were calculated by the proposed constitutive relationship.The calculated results agreed well with the experimental results.The effects of the spacing,diameter,yield stress of transverse reinforcement and section form on lateral confinement were investigated in L-shaped section.The results show that the spacing,diameter and yield stress of transverse reinforcement has significant influence on axial load versus strain curves.The axial load,peak strain,and strain ductility increase,compared with no lateral confinement of transverse reinforcement.The section form has little influence on axial load versus strain curves.