Investigation on Seismic Performance and Retrofit of Reinforced Concrete C-bent Columns

由于偏心轴力和弯矩的作用，C形柱在极端地震动作用下很容易受到破坏。一旦地面激励变得广泛，塑性铰点处的柱子在受压侧开始受压破坏，导致该方向上的显著残余漂移。本文通过对钢筋混凝土柱的混合加载试验和分析，阐明了C形柱的特殊地震反应。在加载试验结果的基础上，建立了考虑恒定轴力作用下弯扭复合作用的非线性滞回模型。提出并制定了两种抗震加固措施。通过加载实验，验证了这些方法对消除压缩侧残余漂移的有效性。将有限元方法应用于C弯柱，结果表明，有限元方法能较好地预测C弯柱的非线性滞回性能。采用本文建立的弯扭组合非线性滞回模型，分析了C形柱支承桥梁的强非线性地震反应。

C-bent columns are vulnerable under extreme ground motions due to eccentric axial force and bending moment. Once ground excitation becomes extensive, compression failure of column at the plastic hinge is initiated at the compression side resulting in a significant residual drift in this direction. In this study, peculiar seismic response of C-bent columns was clarified based on hybrid loading tests and analysis on reinforced concrete columns. Based on results of loading experiment, a nonlinear hysteretic model was developed to take account of combined bending and torsion under a constant axial force. Two seismic retrofit measures were proposed and developed. Through loading xperiment, effectiveness of those methods for mitigating residual drift in the compression side was verified. Application of finite element method to C-bent columns showed that finite element method predicts peculiar nonlinear hysteretic behavior of C-bent columns with reasonable accuracy. Strong nonlinear seismic response of bridges supported by C-bent columns was analyzed using a nonlinear hysteretic model for combined torsion and flexure which was developed in this study.