Research Of Progressive Collapse Of High-rise Reinforced Concrete Structure Under Blast Loading

Recently,the explosion caused by the terrorist attacks and the explosion accident caused by gas and other dangerous goods occurred frequently,which not only caused a large number of casualties and property losses,but also brought a series of secondary disasters,such as partial or global collapse of the building structure caused by the explosive load,also aggravate the injury and loss of the incident.In this paper,using ANSYS/LS-DYNA,taking the typical frame structure and shear wall structure as examples,the progressive collapse of the high rise reinforced concrete structures under blast loading is studied,which provide a theoretical basis for the analysis of structural resistance to progressive collapse.The main research work and achievements of this paper are as follows:(1)Using the method of multiscale modeling,the finite element models of the reinforced concrete frame structure and the reinforced concrete shear wall structure are established respectively,and the structural model,material model and load model used in the finite element model are selected respectively.The reliability of ANSYS/LS-DYNA in the research of the impact of the explosion load on buildings is verified.(2)The collapse and dynamic response of structures are analyzed when the explosives are set in front of corner column and side column respectively.The collapse process and collapse range of buildings in the above cases were compared.The results show: When the explosion occurred in front of the reinforced concrete structure column,the column lost the carrying capacity due to shear failure,at the same time adjacent beams and plates are destroyed.Finally,the structure partial progressive collapse occurred because of the serious damage of the adjacent structure under the structural internal force redistribution.In the same amount of explosive and distance,no matter where explosives are located,the vertical displacement and velocity time histories of adjacent columns are different.The progressive collapse range of structures when the explosive is set in front of side column of the frame structure is wider than it when the explosive is set in front of corner column.(3)The dynamic response and the failure of reinforced concrete frame structures under different TNT equivalent explosive are studied.Research shows that: with the increase of the TNT equivalent,the peak stress value of the vertical reinforced bars in the column,the peak vertical displacement value of the top of column and its peak horizontal displacement value in X direction will increase accordingly.When the TNT equivalent is 2,000 kg,the progressive collapse of the structure is different when the explosive is set in different place.(4)The failure and collapse of shear wall structures under the explosion at different positions is studied respectively.The results show: the torsional-shear failure of the reinforced concrete shear wall with L-shape occurred by the explosion.The structure can come to a new equilibrium under gravity in the case that the TNT equivalent is smaller.When the TNT equivalent is larger,the failure of the wall is too serious to support the upper structure.Eventually,the partial progressive collapse of this structure occurred.In the case of the same TNT equivalent,the failure of the middle wall tends to cause the collapse of the structure.(5)The dynamic response and the failure collapse of the shear wall structure under different TNT equivalent explosion are studied.The result shows that: the more the TNT equivalent,the sooner the structure collapses,and the faster the collapse speeds is.