Analysis Of Lateral Impact Behavior Of The Simple-supported Concrete-filled Square Steel Tube With I-shaped CFRP Profiles

In recent years,due to its characteristics and good mechanical properties,concrete-filled steel tube(CFST)structures have been widely used in the field of civil engineering and have increasingly become the preferred load-bearing components for construction projects or bridge piers.During the period of service of the building structure,in addition to the static load,it may also be subjected to accidental loads such as ship and car impact,resulting in serious damage to the building structure or even loss of bearing capacity.Therefore,it is necessary to conduct in-depth research on the performance of concrete filled steel tube under impact load.With the development of building structures and materials in the direction of higher performance,more new types of concrete-filled steel tube structures combined with FRP composite materials have appeared,and placing I-shaped CFRP profiles in the core area of concrete-filled steel tubes is a new type of composite structure.Many studies have been carried out on the static performance of this new type of member in this years,such as axial compression,bias compression,and bending performance.However,related research on its dynamic response and mechanical performance under impact load has not been carried out,so it is necessary to Perform analysis.In this paper,mainly adopts the method of finite element simulation and uses ABAQUS/Explicit finite element software to analyze the dynamic response of concrete-filled square steel tube with I-shaped CFRP profiles under simply supported conditions and lateral impact loads from several aspects.The main research content and results of this article are as follows:First of all,based on the selected constitutive relationship of steel tube and core concrete,the plastic damage model and the strain rate effect were considered to calculate the material strength under dynamic response.In order to make the simulation more accurate,the unit types,contact relations,and boundary conditions of the falling weight,steel pipe,core concrete,CFRP profile and other structures were reasonably selected,and the meshes of each part were finely divided.On this basis,the model of concrete-filled square steel tube with I-shaped CFRP profiles was established and the impact process was analyzed.The performance with whole process analysis of the components under lateral impact load was analyzed based on the established models.The impact dynamic response of the component was comprehensively analyzed from the six aspects of failure mode,impact force and deformation development process,stress development,strain rate distribution,stress-strain relationship,and energy state,and its behavior under lateral impact load,force and deformation,plastic development and energy consumption state of each part of the component were discussed.By changing the impact height,impact quality,steel ratio,shear span ratio,material strength and other conditions,the impact resistance of concrete-filled square steel tube with I-shaped CFRP profiles was analyzed.The results show that the simply supported components at both ends mainly undergo bending deformation,and local buckling occurs in the middle of the span under the impact loads;The impact load has a large strain at the section where the plasticity is fully developed,and the main elastic deformation occurs far away from the mid-span section;The components has good deformation ability when resisting the impact load,and the plastic performance is the main energy consumption of the components during the impact;A comparative analysis of concrete-filled square steel tube with I-shaped CFRP profiles and ordinary concrete-filled square steel tube components shows that CFRP can not only improve the impact resistance of the components and enhance the bending stiffness of the section,but also effectively improve the ductility and deformation ability of the components.The impact height,impact quality,steel ratio,and shear span ratio have a greater impact on the flexural strength of components.In addition,as the impact energy and shear-span ratio increase,the mid-span deflection of the component increases,and the time required to resist the impact is prolonged;The peak impact force is slightly affected by the strength of concrete,but it increases significantly with the increase of impact energy,steel ratio and yield strength of steel tube.