低速冲击下RC梁的动态响应和破坏机理研究

DYNAMIC RESPONSES AND FAILURE MECHANISM OF RC BEAMS TO LOW VELOCITY IMPACT

考虑材料非线性和应变率相关性等因素的影响,运用LS_DYNA非线性有限元软件对RC梁横向低速冲击试验进行了数值模拟,从动态损伤扩展、冲击能量转化等方面研究了RC梁的冲击响应过程和破坏机理。结果表明:RC梁的冲击响应过程可分为局部响应、整体响应和回弹变形三个阶段;RC梁的损伤主要发生在局部响应阶段,梁体变形主要发生在整体响应阶段;局部响应阶段的冲击力完全由梁体惯性力平衡,整体响应阶段的变形模式和截面弯矩分布与刚塑性模型基本相同;受拉钢筋变形耗能是RC梁最主要的冲击耗能机制。

The tests of RC beams under lateral low velocity impact were simulated by the nonlinear finite element software LS_DYNA, including the effects of material nonlinearity and strain rate dependent, and the dynamic response and failure mechanism of RC beams were analyzed for the dynamic damage extension and impact energy transition. The results showed that the dynamic response of RC beams can be comprised of three stages: the local response stage, the overall response stage and the resilient stage; the damage of RC beam mainly occurred in the local response stage, the deflection of RC beam mainly occurred in the overall response stage; the impact force was completely balanced with the inertia force of RC beams within the local response stage, and the deflection model and axial distribution of the bending moment on cross sections were consistent with the rigid-plastic model within the overall response stage; the energy dissipation of tensile rebar by deformation was the foremost energy dissipation mechanism of RC beams under impact.