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为模拟钢筋混凝土柱在轴力、剪力和弯矩耦合作用下的非线性滞回特性,利用显式中心差分法,建立一种基于显式算法的弯剪纤维单元模型,并引入到结构精细化模拟分析(RSAPS)平台中。该模型基于Timoshenko梁理论,材料模型选用基于修正斜压场理论(MCFT)的二维钢筋混凝土本构模型。应用RSAPS平台分别模拟往复荷载作用下发生弯曲、弯剪和剪切破坏的钢筋混凝土柱的滞回性能,并将分析结果与试验和未考虑剪切变形的纤维单元模型模拟结果进行对比。结果表明:对于发生弯曲破坏的构件,由于剪切变形较小,未考虑剪切变形的纤维单元和弯剪纤维单元均可以较好地模拟构件的滞回性能;而对于发生弯剪破坏和剪切破坏的构件,采用未考虑剪切变形的纤维单元模型,会高估构件的初始刚度和耗能能力,也会高估其受剪承载力;而所提出的弯剪纤维单元模型能较好地模拟构件的刚度和承载力退化,同时,也能较好地模拟滞回曲线中的捏缩现象,模拟结果与试验结果吻合较好。
In order to simulate the nonlinear hysteretic behavior of reinforced concrete columns under the coupling of axial force, shear force and bending moment, an explicit center-difference method was used to establish a bending-shear fiber unit model based on an explicit algorithm and introduced into the structural refinement Simulation Analysis (RSAPS) platform. The model is based on the Timoshenko beam theory and the material model is a two-dimensional reinforced concrete constitutive model based on modified barometric field theory (MCFT). The RSAPS platform was used to simulate the hysteretic behavior of RC columns subjected to bending, bending and shearing under cyclic loading respectively. The results of the analysis were compared with those of the uniaxial and no-shear models. The results show that for the member with bending failure, the hysteretic behavior of the member can be well simulated due to the small shear deformation and the failure of the fiber unit and the bending-shear fiber unit without considering the shear deformation. However, Shear failure members, which adopt fiber unit model without considering shear deformation, will overestimate the initial stiffness and energy dissipation capacity of members and also overestimate the shear capacity of the members. However, The stiffness and the bearing capacity of the simulated member are degraded. Simultaneously, the phenomenon of pinching in the hysteretic curve can be well simulated. The simulation results are in good agreement with the experimental results.