考虑轴-弯-剪耦合效应的钢筋混凝土柱滞回性能研究

Hysteretic behavior investigation of reinforced concrete columns accounting for axial-flexure-shear interaction

试验研究及震害调查发现:由于配箍不足或箍筋间距过大,地震作用下钢筋混凝土柱易发生剪切破坏,继而发生轴向破坏。采用纤维截面的钢筋混凝土梁柱单元及与之串联的剪切弹簧以及轴向弹簧考虑钢筋混凝土柱的轴-弯-剪耦合效应,其中纤维梁柱单元用于模拟柱的弯曲机制,与梁柱单元串联的剪切弹簧和轴向弹簧用于模拟剪切机制和轴向机制,并利用单轴材料模型中的Limit State Material及其相应的Shear Limit Curve和Axial Limit Curve确定材料的剪切破坏与轴向破坏失效点,最终从单元层次上定义轴-弯-剪耦合效应。为验证该数值模型的合理性,选取不同破坏形式、轴向力与水平循环往复荷载共同作用下拟静力试验的钢筋混凝土柱,借助Open Sees分析软件模拟其滞回性能。模拟结果与试验结果的对比分析表明:考虑轴-弯-剪耦合的串联模型能较好地模拟钢筋混凝土柱的强度、刚度退化及捏拢效应等,且能够反映钢筋混凝土构件在复杂应力条件下的受力性能。

The experimental research and the field reconnaissance have demonstrated that reinforced concrete columns with light or widely spaced transverse reinforcement are vulnerable to shear failure and subsequent axial failure during earthquake shaking. A fiber beam-column element in conjunction with shear spring and axial spring atta ched to its ends was proposed to simulate the axial-flexure-shear interaction of reinforced concrete columns. Fiber beam-column element is used to simulate flexure mechanism and shear spring and axial spring are used to simulate shear mechanism and axial mechanism respectively. And the Limit State Material models and the corresponding shear limit curve and axial limit curve are used to determine the shear and axial failure point. This model finally can define the axial-flexure-shear interaction effect from the element level. To validate the reliability of this proposed numerical model, the reinforced concrete columns with different failure modes under axial and reversed horizontal static loading were modeled via OpenSees and their hysteretic behavior was simulated. Comparison of the simulated and experimental results show that the model considering the effect of axial-flexure-shear interaction provides a preferable estimation for the pinching, strength and stiffness degradation of the reinforced concrete columns. It can simulate the mechanical properties of the reinforced concrete members under complex stress conditions.