梁柱节点的单元模型校准与其组合体试验方法对比

梁柱节点是钢筋混凝土结构中受力性能复杂的重要部位，其有限元模型的合理性是结构非线性数值模拟成功实施的关键。在OpenSees结构分析平台上，以力学模型较为细化的梁柱节点单元(beam-column joint element)模型为研究对象，在合理确定梁柱节点单元各分量的参数取值方法的基础上，分别以多组钢筋混凝土梁柱组合体试件的梁端加载、柱端加载试验结果为依据，对有限元模拟结果的准确性进行校准，并在此基础上分析了同一组合体试件分别采用梁端加载、柱端加载两种试验方法时模拟结果的差别。结果表明：梁柱节点单元中模拟节点内纵筋滑移分量的材料模型存在较明显误差，当滑移较小时，模拟结果有相对较好的精度；当梁纵筋滑移量较大时，模拟的组合体整体滞回性能与试验结果相比误差较大；当梁、柱纵筋黏结滑移值较小时，同一组合体试件在梁端加载、柱端加载两种试验方法下的节点非弹性变形相近。

Calibration of beam-column joint element model and comparison of loading methods of beam-column subassemblages

Beam-column joint with complex mechanical behavior is an important part in reinforced concrete structures, thus the accuracy of beam-column subassemblage finite element model is one of the essential components in nonlinear numerical simulation of structures. Based on OpenSees platform, beam-column joint element model developed by more detailed inelastic mechanism was analyzed comprehensively. On the basis of determining parameters of each element component reasonably, beam-column joint element was calibrated according to the experimental results of beam-column joints subjected to cyclic loads acting on beam ends or column ends respectively. The difference between two methods, namely loading at beam ends or loading at column ends for the same beam-column subassemblage, was analyzed based on the calibrated beam-column joint element model. The results show that significant errors exist in the skeleton curve of uniaxial material model for simulating reinforcing bar slippage within joint, which is one of the two critical components of beam-column joint element. When the slippage of beam bar is small, a relatively better simulation results could be obtained. However, when the bar slippage in joint becomes larger, greater errors occur in the simulation results of global hysteretic behavior of beam-column subassemblages. When the slippage of bar is small, joint inelastic deformations of same beam-column subassemblage subjected to cyclic load acting on beam end or column end are similar.