Numerical Simulation Of Mechanical Properties Of Concrete-filled Steel Tube Under Impact Loading

Concrete-filled steel tube structure is a new combination of steel and concrete after reinforced concrete structure,It is a structure filled with concrete into a steel pipe.In the concrete-filled steel tube structure,the steel tube interacts with the concrete.The steel tube increases the ductility and plasticity of the concrete,and the concrete improves the stability and the compression resistance of the steel tube.Although the superiority of the concrete-filled steel tubular structure has been widely used,its mechanical properties under dynamic loading are still in an exploratory stage.In order to explore the influence of different parameters on the mechanical properties of concrete-filled steel tube under impact loading,the SHPB experiments of concrete filled steel tubes with different parameters are designed.At the same time,using ANSYS/LS-DYNA numerical simulation software,the SHPB experiment was simulated,and an extended simulation of the parameter variables was designed based on this.The details are as follows:1.The basic principle of the SHPB experiment and two premise assumptions,namely the one-dimensional assumption and the assumption of uniform stress,are described.Based on the assumption,the two-wave method and the three-wave method are deduced.Several issues of SHPB experimental technology were analyzed and discussed and corresponding solutions were proposed.Four axial-to-axial impact test specimens and one lateral impact test specimen are designed for each of the four concrete-filled steel tubular specimens.The parameters of the axial impact direction are:2mm and 3mm steel pipe wall thickness,c30 and c45 concrete strength grades;The parametric variables in the lateral impact direction are: 2mm and 3mm steel tube wall thickness,c30 and c45 concrete strength grades.The experimental data was processed using the three-wave formula,the stress-strain curve of steel-concrete-filled concrete was analyzed in the axial direction,and the force-displacement curve of steel-concrete-filled concrete was analyzed in the lateral direction.From the experimental results,the larger the wall thickness of the steel tube,the higher the compressive bearing capacity of the concrete filled steel tube specimen is.For concrete-filled steel tube concrete specimens with the same steel tube wall thickness and impact pressure,the higher the concrete strength,the higher the compressivebearing capacity of the steel tube concrete specimen.2.The numerical simulation of the SHPB experiment of concrete-filled steel tubular specimens in the direction of axial punching and lateral punching and the extension of the parametric variables were simulated.The establishment of the finite element model was introduced in detail,including the selection of elements,the definition of contact and the selection of material models.The parameters of the extended simulation design parameters were the same conditions as those of different steel tube wall thicknesses of 2.5mm,3mm,4mm and 5mm.The same conditions,different concrete strength grade c35,c40 and c50 steel pipe concrete specimens.The results of numerical simulation and numerical extension simulation of SHPB experiments show that the larger the wall thickness of the steel tube concrete specimens with the same impact pressure and concrete strength,the higher the compressive bearing capacity of the concrete filled steel tubular specimens.For concrete-filled steel tube concrete specimens with the same steel tube wall thickness and the same impact pressure,the greater the concrete strength level,the higher the compressive bearing capacity of the concrete-filled steel tube concrete specimen.Comparing the results of two parameters of wall thickness of steel pipe and concrete strength,it is found that the effect of steel pipe wall thickness on the bearing capacity of steel tube concrete is greater than the effect of concrete strength on the bearing capacity of steel pipe concrete.