Impact Resistance Of Spiral Reinforcement/Inner Steel Tube Reinforced Concrete-filled Weathering Steel Tubular Members

Spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members is a new type of composite concrete filled steel tube members formed by inserting spiral reinforcement or inner steel tube into the concrete filled steel tube members.Compared with ordinary concrete filled steel tube,this type of component has the advantages of good atmospheric corrosion resistance and higher load-bearing capacity,and its application prospects are broad.Engineering structures in normal use in addition to bear ordinary static loads,but also may suffer from accidental dynamic loads,such as truck impact viaduct piers,cargo ship impact bridge,etc.Once this unexpected dynamic load occurs,it can cause serious damage or even direct collapse to the structure,bringing huge losses to people’s lives and properties.Therefore,it is necessary to analyze the dynamic response of the members under dynamic loading and their impact resistance performance.In this paper,the mechanical response and impact resistance of spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members under the action of lateral impact were investigated using the combination of experiments and numerical simulations as follows:(1)A series of drop hammer impact tests were conducted on the spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members to record the damage mode,impact time course curve,mid-span displacement time course curve and strain time course curve of the specimens,and to analyze the effects of design parameters such as outer steel tube wall thickness,inner steel tube wall thickness and spiral reinforcement diameter on the impact resistance of the specimens.The results show that under the simple support condition,the spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members all exhibit bending damage without obvious shear deformation;the specimens show obvious plastic hinge at the impact point,and the rest of the positions were basically kept straight without obvious deformation,showing excellent impact resistance;compared with the spiral reinforced concrete filled weathering steel tube members,the impact resistance of the inner steel tube reinforced concrete filled weathering steel tube members is more excellent.(2)The intrinsic model of weathering steel was proposed based on the secondary flow plastic model of steel,on which the numerical model of lateral impact of spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members was established,and the strain rate effect of the material under dynamic load was considered;the correctness and reliability of the finite element model were verified by comparing the calculated results of the finite element model with the damage modes,impact force time course curves and mid-span displacement time course curves recorded in the test.The results show that the established finite element model can well simulate the dynamic response of spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members under lateral impact.(3)The dynamic response of the spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members under the action of lateral impact was analyzed in the whole process by simulation,including the development process of impact and deformation,energy dissipation mechanism,bending moment distribution,damage evolution and the interaction between the reinforcement cage,steel tube and concrete.The results show that the spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members has good impact resistance,and the impact energy is mainly absorbed by the outer steel tube,followed by concrete,inner steel tube and reinforcement cage.(4)Parametric analysis was conducted on the impact resistance of spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members,mainly including the ratio of impact mass to velocity,the ratio of built-in steel diameter to thickness,the ratio of internal and external steel content,boundary conditions and impact location,etc.On the basis of this,design recommendations for spiral reinforcement/inner steel tube reinforced concrete filled weathering steel tube members were proposed based on the idea of improving the impact resistance of the specimens.