考虑箍筋约束的套箍加固RC轴压方柱承载力计算

Calculation of bearing capacity of RC axial compression square column strengthened with jacket considering the stirrup confinement

对套箍加固RC轴压方柱的极限承载力N_(u)计算方法进行了理论分析,在推导N_(u)计算式过程中,综合考虑了加固柱的如下特性:一是核心柱混凝土受到了新旧箍筋的双重约束作用,二是核心柱初始荷载P_(1)对N_(u)的影响。根据几点基本假定,推导了新旧箍筋约束混凝土本构关系特征值的计算方法,在此基础上分析了P_(1)对N_(u)的影响,推导了套箍层混凝土和钢筋强度折减系数α_(c)和α_(s)的计算方法,进而建立了N_(u)的计算式。验证表明,公式计算结果偏安全,与试验结果总体吻合情况良好。

The calculation method of N_(u) for ultimate bearing capacity of RC axially compressed square column strengthened with jacket was analyzed theoretically.In the process of deriving N_(u) calculation formula,the following characteristics of strengthened columns were comprehensively considered.One is that the concrete of the core column has been restrained by the new and old stirrups.The second is that the initial load P_(1) of the core column has effect on N_(u).Based on a few basic assumptions,the calculation method of the eigenvalues of the confined concrete constitutive relationship restrained by the new and old stirrups was deduced.On this basis,the influence of P_(1) on N_(u) was analyzed.The calculation methods of strength reduction coefficients α_(c) and α_(s) of concrete and steel in hoop layer were derived.Furthermore,the calculation formula of N_(u) was established.The verification results show that the formula calculation results tend to safe and are in good agreement with the experimental results.