| The steel-concrete composite structure is widely used in the construction market.According to its stress mechanism,it is divided into concrete filled steel tube and steel tube confined concrete.In recent years,confined concrete with various composite materials derived from steel tube confined concrete.Many scholars have studied the fire resistance,bearing capacity,and seismic resistance of composite structures such as stainless steel-filled steel tube concrete,double-filled sandwich steel tube concrete,and FRP-steel tubular concrete.Some scholars have studied the low-speed lateral impact of concrete-filled steel tubes(joint forces acting on steel tubes and concrete),but little research has been done on the lateral impact of steel tube confined concrete(core concrete only).Therefore,this paper studies the lateral impact properties of steel-concrete confined concrete,and compares the advantages and disadvantages of lateral impact properties between steel-concrete confined concrete and traditional steel-concrete concrete's.The main contents are as follows:(1)Based on the stress mechanism of concrete-filled steel tube,three kinds of steel pipes with different cutting modes were established.Mode A: no circular cutting of the steel tube,conventional steel tube concrete.Mode B: A ring piece with a cutting width of 10 mm is centered at 300 mm from both ends of the member.Mode C : on the basis of mode B,the center of the specimen cuts the 5mm ring.Due to the discontinuity of the steel pipe,Mode B and Mode C,the external load at the end can only act on the core concrete,the steel pipe confined concrete is formed.(2)The similarities and differences between steel tube confined concrete and concrete-filled steel tube were analyzed,and pointed out the essential differences between them.Only the core concrete of the concrete-filled steel tubular structure is subjected to stress,and the outer thin-wall structure is not constrained by force,In generalized,it can be referred to as steel pipe confined concrete.At the same time,the force relationship between steel tube confined concrete's tube and core concrete is given.(3)Finite-software ANSYS/LS-DYNA is used to numerically simulate the concrete filled steel tubular structures,establishes a numerical model of the concrete filled steel tubular column with different circumferential cutting modes with fixed boundary conditions.Comparing the results obtained by numerical simulation with the experimental results,it was found that the trend of the impact time history curve,the peak impact force,the platform value,and the valley value and the working time of the deflection curve were in agreement with the experimental data.(4)On the basis of verifying that the numerical model and the obtained data all have certain reliability,the influence of parameters such as impact height,load ratio and cutting mode on the lateral impact properties of steel-concrete confined concrete was analyzed.The results show that the peak value of the impact force,the platform value and the maximum deflection in the mid-span increase with the increase of the impact height and load ratio under the same model,different heights and load ratios;the comparison of the same load ratios in different modes,at the same height,Under the condition of no axial compression or low load ratio,the impact resistance of conventional concrete-filled steel tube is better than that of steel-concrete-concrete.Under high load ratio,the impact resistance of confined concrete is better than that of traditional concrete.(5)In engineering practice,steel-pipe confined concrete and steel-pipe concrete have strong bearing capacity and high ductility.They are generally used as bearing-type engineering piles,bridge pier columns,and large-span structural frame columns.However,accidental collisions inevitably occur during service.Based on this,at the end of this paper,the engineering practice recommendations is given: The concrete-filled steel tube is selected as the bearing column. |
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