纤维模型中非线性剪切效应的模拟方法及校核

Fiber Model Based Nonlinear Shear Effect Modeling Method and Its Calibration

传统纤维模型忽略了非线性剪切效应,难以用于剪力墙等构件的非线性反应模拟。建议采用直接在截面层次上定义非线性剪切恢复力关系的方法。构件截面的弯曲刚度、轴向刚度通过传统纤维模型的方法积分得到,截面的剪切刚度根据所定义的截面剪切恢复力关系得出,将剪切刚度与弯曲、轴向刚度进行组合后得到组合截面的整体刚度矩阵。利用OpenSees提供的Section Aggregator功能在OpenSees平台上方便地实现了对截面层次非线性剪切效应的模拟。以中国完成的15片剪力墙抗震性能试验的实测结果为依据,对用于确定剪力墙的剪切恢复力骨架曲线各特征参数的Hirosawa公式进行了校核、修正。并对中国的2片典型剪力墙低周反复试验进行了模拟分析。结果表明,考虑剪切效应的模拟方法均能更好地模拟出剪力墙的最大抗剪承载能力和刚度退化、捏缩效应,不考虑剪切效应的模拟结果难以反映剪力墙的实际受力特性。

The conventional fiber model neglects the nonlinear shear effect,and is difficult to simulate the nonlinear response of the shear wall and other similar components with fiber model.The method of directly defining the nonlinear shear restoring force relationship at the section level was suggested.Within this method,the flexural and axial stiffness could be calculated by the traditional fiber model formulas,while the shear stiffness was calculated according to the predefined sectional shear restoring force relationships.The combined integrated sectional stiffness matrix could be obtained by combining the shear stiffness,flexural stiffness and axial stiffness.Based on the OpenSees framework and its functional command of Section Aggregator,it was convenient to simulate the nonlinear shear effect at the section level.Taking the experimental results of 15 shear walls of China as the benchmark,the formulas of Hirosawa,which was used to define the characteristic parameters of the shear restoring force skeleton curve,were calibrated and modified.The low cyclic reserved loading tests of two typical shear walls were simulated by this method.Results showed that the modeling method of considering the shear effect could simulate the maximum shear force,stiffness degradation and pinch shrinkage of the shear wall more effectively,while the actual mechanical behavior of shear wall could not be obtained by the modeling method that ignore the shear effect.