Dynamic Response Of Steel Plate Concrete Composite Structures Under Blast Loads

Steel plate concrete composite(SPCC)structure which can give full play to the advantages of concrete and steel,has various structural forms,and has the advantages of light weight,good ductility and seismic performance,simple construction and remarkable economic effect.As a sequence,it has been widely used in nuclear power engineering,underground engineering,offshore structure,offshore platform and other building structures.In addition to bearing various static loads,wind loads and earthquake actions,it may also bear the impact of accidental explosion during its service.Relevant research has shown that the anti-explosion performance of it is better than that of the ordinary reinforced concrete structure.At present,the anti-explosive performance of SPCC structure and its application research have become one of the hot spots in the fields of protection engineering and anti-terrorism and explosion protection.However,the research on the dynamic response and failure mechanism of SPCC structure under blast loads is limited.Most of the researchers only considered the density and thickness of core concrete,and they don’t carry out the research on the dynamic response of SPCC structure under different charges and different explosion distances.In addition,mesh size has an important influence on the accuracy of the numerical results,and the anti-explosion performance of SPCC structure is different due to the differences of the shear connectors.Therefore,it has important theoretical significance and engineering reference value to study the anti-explosion and mesh sensitivity of steel plate concretecomposite structure.Based on this,the commercial finite element software ABAQUS is used to study the anti-explosive performance of SPCC structure from the following four aspects of research.Firstly,the dynamic response of SPCC plate under blast loads is studied.Secondly,two groups of orthogonal experiments are designed to investigate the mesh size sensitivity of dynamic performance of SPCC plate under different factors.Thirdly,the difference of blast resistance of SPCC plate with stud connectors and J-type shear connectors is compared and analyzed.Finally,the dynamic response of SPCC beam is discussed.The main research results are as follows:(1)By studying the failure mode and dynamic performance of SPCC plate with different charge quantity and different blasting distances,the numerical results shows that the explosion stress wave diffuses along the blast center position to both sides of the composite plate,the stress value of the composite plate increase continuously in the elastic stage,and then decrease when the steel plate reaches the plastic stage.The failure mode of SPCC plate is related to the explosive quantity and distance.The larger the explosive quantity and the smaller the detonation distance,the more obvious the damage degree of the composite plate.When the TNT explosive amount is 100 kg and the blasting distance is 2.5 m,the composite plate warps obviously and plastic hinge appears.The existence of steel plate effectively limits the spalling of core concrete.Under the condition of the same blast distances,the larger the amount of explosive,the more obvious the deformation of the composite plate,the greater the mid span deformation and peak velocity.When the explosive quantity is the same(100 kg),the mid span deflection of steel plate concrete composite plate is 1.53 times of that of 7.5 m when the explosive distance is 5.0 m.When the explosive quantity is the same(100 kg),the mid span deflection of steel plate concrete composite plate is 5.01 times of that of 7.5 m when the explosive distance is 2.5 m.(2)When the mesh size of the encryption area is 15 mm,the calculation accuracy of the simulation is more accurate than that of other dense mesh sizes,which is more consistent with the experiment.The mesh-size influence of the non encrypted area on the accuracy of the calculation results is relatively small;when the explosion proportional distance is 0.54 ～ 0.86,and the mesh size of 10～15mm are recommended.When the explosion proportional distance is 0.86 ～ 1.08,it is suggested that the mesh size of 15 ～ 20 mm should be adopted.(3)Under the same working conditions,the maximum deflection of the composite plate with stud connectors is 2.23 mm larger than that of the composite plate with J-type shear connectors.The anti-explosion ability of SPCC plate with J-type shear connector is a little better than that of the SPCC plate with stud connector.However,the difference is not limited.Combining the stress value and failure mode of the steel plate concrete composite plate with studs and the steel plate concrete composite plate with J-type shear connectors,it can be seen that the difference between the two is not big.The maximum stress value of the explosion facing surface is basically the same,but the synergy of the J-type shear connector is better.As a sequence,more suitable shear connector should be chosen according to the actual engineering situation.(4)The main failure mode of SPCC beam under blast loads is firstly bending failure,then shear failure of core concrete,and steel plate buckling in the shear failure process of concrete.The main stress component is J-type shear connector,the stress value of steel plate and concrete bearing blasting load is small.Moreover,J-type shear connector bears most of the stress of blast load and has good anti explosion ability,which could prevent the separation of steel plate and concrete.