Impact Response Of Steel-concrete-steel Sandwich Panel With Energy Absorption Connector

In recent years,the impact events have been reported frequently,which have caused damage to civil structures.Therefore,the impact resistance of civil structures is important to study.Thus,a novel polyurethane foam-filled energy absorption connector with asymmetric pleated plates and a profiled steel plate-concrete-flat steel plate sandwich panels with two ends simply supported were presented in this paper.In addition,the impact resistance of the sandwich panel with energy absorption connector was also studied in this paper.The specific research contents are as follows:(1)The impact response of polyurethane foam-filled energy absorption connector with asymmetric pleated plates was researched through drop-weight impact tests and FE simulations.The results showed that the deformation process of the connectors could be divided into three stages.By comparing the impact response of the connectors with different parameters,it could be found that the energy absorption parameters of connectors with asymmetric pleated plates could be significantly improved compared with connectors with symmetric pleated plates.The novel connector proposed in this paper was proved to have higher energy absorption characteristics.In addition,filling polyurethane foam could also improve the energy absorption parameters of connectors.Besides,a theoretical model,considering strain rate effect of polyurethane foam and steel,was also proposed to predict energy absorption–displacement relationships of the connectors subjected to impact loading.(2)In this paper,the FE method based on LS-DYNA was adopted to study the profiled steel plate-concrete-flat steel plate sandwich panels with two ends simply supported under the impact of hammers with different shapes.The deformation mode,force–time history and failure mechanism of the composite plates were obtained.The results showed that the deformation of the sandwich panel under the impact of hemispherical hammer could be divided into the global deformation and the local concave deformation,while under the impact of flat hammer,the deformation could be divided into the global deformation and the local convex deformation.According to the characteristics of the force–time history,the impact process of the sandwich panel could be divided into three stages.Comparing with the panel impacted by hemispherical hammer,there occurred a peak in the curve of the impact force–time history when the panel was impacted by flat hammer.For the sandwich panel impacted by hemispherical hammer,the flat steel plate cracked at the impact position;for the sandwich panel impacted by flat hammer,the concrete cracked at the bottom of sandwich panel at the impact position,and also cracked at the free boundary of sandwich panel.Besides,by comparing the sandwich panels with different parameters,it could be found that the global deformation and total deformation of profiled steel plate-concrete-flat steel plate sandwich panel was lower comparing with the ordinary SCS panel under the impact load in case of the same amount of materials.Increasing the height a well as the thickness of profiled steel plate could also improve impact resistance of sandwichpanel.(3)The deformation mode,force–time history and internal energy–time history of the sandwich panels with energy absorption connectors under the impact of hammers with different shapes and momentum were obtained by FE method based on LS-DYNA.Two kinds of deformation modes of the sandwich panels with energy absorption connectors could be observed under the impact loading.The local concave deformation could be observed then the structure was impacted by hemispherical hammer and the local convex deformation as well as the peak inertial impact force could be observed then the structure was impacted by flat hammer.The results also showed that the value of global deformation of sandwich panel could be high when the initial momentum of the hammer was too high or too low in case of the same initial kinetic energy.Besides,setting of energy absorption connectors could effectively reduce the global deformation of sandwich panel and significantly improve the impact resistance of the protection structure proposed in this paper,but the energy absorption of connectors as well as the impact resistance of the protection structure would reduce when the stiffness of connectors was too high or too low.