冲击荷载下内配圆形钢管混凝土的方形叠合柱剩余承载力研究

Study on residual bearing capacity of square concrete⁃encased circular concrete⁃filled steel tubes under impact load

为研究内配圆形钢管混凝土方形叠合柱侧向冲击后剩余承载力性能,利用有限元软件ANSYS/LS-DYNA建立了叠合柱冲击后受压承载力数值模型。对经典侧向冲击试验进行了数值模拟,分析表明该数值模型能够较好地模拟结构柱的破坏形态、冲击力和挠度。基于该模型研究了不同参数下叠合柱侧向冲击后剩余承载力特性,对比了未遭受冲击叠合柱轴心受压承载力,分析两者轴压极限承载力差异,并提出损伤程度评价指标(D_(dag)),量化分析了剩余承载力。结果表明:侧向冲击后叠合柱进行轴压加载直至破坏时易发生弯剪破坏,所消耗的能量相比于未遭受冲击叠合柱降低较多;在相同冲击条件下,冲击速度、轴压比和长细比对叠合柱耐冲击性能和冲击后剩余承载力影响最为显著和全面,而边界条件和钢管壁厚影响较小,但也不可忽视;基于损伤程度评价指标(D_(dag))及对应的损伤描述,可以快速地判定叠合柱的损伤程度,为结构安全提供应对策略。

In order to study the residual bearing capacity of square concrete⁃encased circular concrete⁃filled steel tubes(CFST)after lateral impact,the numerical model for the compressive bearing capacity of composite columns after impact was established by using the finite element software ANSYS/LS⁃DYNA.The numerical simulation was conducted on classical lateral impact test,and the analysis shows that the numerical model can better simulate the failure mode,impact force and deflection of the structural column.Based on this model,the residual bearing capacity characteristics of composite columns under different parameters after lateral impact were studied.The axial compression bearing capacity of composite columns without impact was compared,the difference between the two ultimate bearing capacities under axial compression were analyzed.A damage degree evaluation index(D_(dag))was proposed to quantitatively analyze the residual bearing capacity.The results show that after lateral impact,the composite column is subjected to axial compression until failure,which is prone to bending and shear failure.The energy consumption is significantly reduced compared to the composite column without impact.Under the same impact conditions,the impact velocity,axial compression ratio and slenderness ratio have the most significant and comprehensive influence on the impact resistance and residual bearing capacity of composite columns,while the influence of boundary conditions and steel tube wall thickness is relatively small,but it can not be ignored.Based on the damage degree evaluation index(D_(dag))and corresponding damage description,the damage degree of composite columns can be quickly judged,which can provide coping strategies for structural safety.