Study on residual bearing capacity of square concrete-encased circular concrete-filled steel tubes under impact load
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(Ddag)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(Ddag)and corresponding damage description,the damage degree of composite columns can be quickly judged,which can provide coping strategies for structural safety.
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