爆炸荷载作用下钢框架柱冲击响应与破坏模式的数值模拟

目的运用非线性显示动力学有限元方法分析计算爆炸冲击荷载作用下钢框架柱的冲击响应和破坏模式．方法基于有限元分析程序ANSYS／LS—DYNA建立三维有限元模型，分析钢框架柱在3种爆炸荷载作用下可能发生的破坏模式特征及其影响因素．结果壳单元shell163考虑了局部屈曲效应和剪切应变的影响，可以有效模拟在爆炸荷载作用下钢框架柱的冲击响应和破坏模式．在荷载峰值相同的情况下，荷载持续时间越长，结构的变形越大；荷载冲量相同时，爆炸荷载峰值压力越高，结构的破坏程度越严重．结论钢框架柱的破坏模式与爆炸荷载的作用特征有关：在冲量荷载作用下，钢框架柱倾向发生柱脚剪切破坏和柱中翼缘屈曲破坏；在动力荷载作用下，钢框架柱则倾向发生柱脚剪切破坏；在准静态荷载作用下易发生整体弯曲屈曲破坏．

Numerical Simulation on Impact Responses and Failure Modes of Steel Frame Structural Columns Subject to Blast Loads

Finite element models are developed by using the explicit dynamic analysis nonlinear finite element procedure LS-DYNA, with simulation of the impact responses and failure modes of steel frame columns,to analyze failure modes of steel frame columns and influencing factors under three kinds of blast loading. The results show that the shell element approach is found to predict the effects of local buckling of cross section occurred after the blast loads, and can effectively simulate the impact responses and failure modes of steel frame columns. In the case of the same peak pressure, the longer the duration time, the greater the structural deformation. In the case of the same impulse load, the higher the peak pressure, the more serious the structure damage. It is found that the failure modes of steel frame column under blast loading depend on the blast loading type. The steel frame columns tend to cause shear failure of column base and the flange buckling failure in the middle of columns under impact load;they also tend to cause shear failure of column base under dynamic load;flexural buckling failure of column is liable to be caused under quasi-static load.