中文摘要：

应用非线性有限元方法分析钢筋屈曲引起承载力退化的问题。使用弧长法对荷载—纵向位移（F-u）平衡路线进行全过程跟踪研究。分析混凝土结构中由于局部箍筋锈断导致受压区纵筋在未达到全截面屈服时发生非线性屈曲的规律。分析中考虑不同材料屈服强度、不同几何缺陷（初弯曲）和不同长径比对纵向钢筋承载力退化的影响。拟合大量分析结果，获得实用的F-u曲线方程式。试验研究对比表明，该实用曲线误差较小，可用于评价锈蚀钢筋混凝土结构剩余承载力。

英文摘要：

Nonlinear buckling analysis is applied to bars with degenerated load-carrying capacity. The full load-longitudinal displacement（ F-u ）equilibrium path is theoretically investigated by using finite element approach in conjunction with the arc-length method. Those longitudinal bars in the compression region of concrete section are buckled before reaching yield strength due to local stirrups corroded and cut off has been studied in details. It is found that the yield strength, geometric flaws （initial flexure） and length-to-diameter ratio of reinforcing bars affect significantly the degeneration characteristics of load-carrying capacity of longitudinal reinforcement. Practical equations of F--u curves are obtained by fitting of great quantity of analyzed results. Compared with the test results, the practical curve has less discrepancy and can be used to evaluate the residual load-carrying capacity of corroded reinforced concrete structures.