基于典型失效模式可靠度分析的柱端弯矩增大系数概率评定

提出一种基于典型失效模式可靠度分析的柱端弯矩增大系数（column overdesign factor）η_c的概率评定方法。该方法利用可靠度理论对结构典型失效模式的发生概率进行分析，获得能使结构最可能发生“强柱弱梁”破坏的最优η_c取值。以一栋五层钢筋混凝土框架结构为例，对提出方法进行应用研究，考虑屈服失效、极限变形失效和剪切失效3类失效机制，选取7种典型失效模式。研究结果表明：我国现行规范建议的η_c取值无法保证钢筋混凝土框架结构最大可能发生“强柱弱梁”破坏，而当η_c取值大于3.1时，钢筋混凝土框架结构发生“强柱弱梁”破坏的概率最大。

Probabilistic evaluation of column overdesign factor through reliability analysis for typical failure modes

A probabilistic method through reliability analysis for typical failure modes is presented to evaluate the column overdesign factorη_c. This method aims to determine the optimalη_c that will cause the structural failure in form of ‘strong column-weak beam’ damage by calculating the failure probability of typical failure modes with the reliability theory. To illustrate the application of the presented method, a five-story reinforced concrete (RC) frame was used as the example, and total of three failure mechanisms involving the yield failure, ultimate deformation failure and shear failure were considered through selecting seven typical failure modes. Results show that the suggestedη_c in current Chinese codes cannot ensure the occurrence of the ‘strong column-weak beam’ damage; while the example structure is most likely to undergo the ‘strong column-weak beam’ damage whenη_c is greater than 3.1.