Behaviour Of Stiffener-enhanced Steel-concrete-steel Sandwich Panels With Nested Tube Subjected To Impact Loading

With the occurrence of accidental impact and terrorist attack in recent years,the Protective structure in the field of architecture and civil engineering has become a hot spot.Higher requirements have been put forward for the impact resistance performance of the structure.Steel-concrete-steel(SCS)sandwich panel in the protective structure has become the focus of research because of its excellent impact resistance.In this paper,a new stiffener-enhanced steel-concrete-steel sandwich panel with the circular–triangular nested tube(CTNT-SESCS)is proposed.The energy absorption performances of circular–triangular nested tube(CTNT)under quasi-static and impact loads are studied by test and numerical simulation.The impact resistance of the stiffener-enhanced steel-concrete-steel(SESCS)sandwich beam and panel is studied through experiment,theoretical analysis and numerical simulation.In the end,the impact resistance of the CTNT-SESCS panel is studied by numerical simulation.The research contents are as follows:(1)three types of circular–triangular nested tube with different parameters are designed and made for the research of energy absorbing performance under quasistatic load.The shape of the triangle tube in the middle and the th ickness of the circular tube on both sides were set as variables.Deformation model,relation between force and displacement,and the index of energy absorption are revealed through MTS tests and LS-DYNA finite element model verification.The results show that the standard component has the best geometry shape and energy absorption performance.Moreover,five types of circular–triangular nested tube filled with different volume of foam aluminum are set up.All of each type are used as repeatable tests with flat hammer head.It is found that the performance of the energy absorber of full-filled aluminum foam is better in deformation mode,the relation of force,displacement,and the energy-absorbing performance.(2)a new type of steel-concrete-steel sandwich beam is proposed,in which the stiffeners are introduced into the tension region to improve the flexural behavior of the SCS sandwich beam.The effect of plate thickness,concrete core thickness,presence of stiffeners and the drop height are revealed.All of the deformation mode,dynamic response characteristics and theoretical analysis model are studied by drop-weight impact tests,finite element simulation and theoretical analysis.The bending failure mode and one-side slip characteristics of the SESCS sandwich beam are found,which proves that the existence of stiffeners can improve the impact resistance of the structure.the impact resistance calculation formula and the displacement response prediction model of the SESCS sandwich beam are presented,which are in good agreement with the test results and the finite element simulation results.(3)Based on the research of the SESCS sandwich beam,this paper further studies the the SESCS sandwich panel,The effect of steel plate thickness,concrete core thickness,presence of stiffeners and the drop height are revealed.The deformation mode,failure mechanism and dynamic response characteristics of the SESCS sandwich panel are studied though drop-weight impact tests and finite element simulation.It is found that there is no slip between the top and bottom steel plates during the whole bending process,which proves the structural integrity of the stiffeners and the studs.Moreover,the damage mechanism of concrete is studied,and the excellent impact resistance of the SESCS sandwich panel is verified.(4)the impact resistance of the SESCS sandwich panel with the circular–triangular nested tube is studied.The effect of top steel plate thickness,triangle tube thickness,circular tube thickness,presence of the triangle tube,and presence of the circular–triangular nested tube are revealed.The results show that the circular–triangular nested tube and the triangle tube can improve the impact resistance of the the SESCS sandwich panel,and the circular tube has the best energy absorbing performance.It is also demonstrated that the CTNT-SESCS sandwich panel has excellent impact resistance.