Local Damage And Progressive Collapse Analysis Of Prestressed Assembly RC Frame Structure Under Blast Load

In recent years,assembled structure system is widely used.Based on the advantages of assembled structure system around the world,China Construction Technology Center has proposed a new system of prestressed assembled concrete frame structure,and systematically studied its seismic performance.Compared with the traditional cast-in-place fabricated concrete frame structure,the new system node of the prestressed fabricated concrete frame structure adopts dry connection,which improves the construction speed and will be applied to schools,residential buildings and government buildings in the future.However,terrorist attacks occur frequently at home and abroad,and the consecutive collapse accidents of building structures caused by explosive loads often occur,resulting in huge economic losses and casualties.Therefore,for the new system of pre-stressed assembled concrete frame structure,besides the systematic study of its seismic performance,the dynamic response under blast loads is also needed.And the performance evaluation of progressive collapse is studied in depth.This paper takes the prestressed assembled concrete frame structure system proposed by the China Construction Technology Center as the research object,establishes the finite element model of the prestressed assembled concrete structure and verifies the correctness of the material type and parameters used in the model.The column is the main force component of the structure and the key component to prevent the continuous collapse.In order to obtain the pre-stressed assembled concrete structure column more accurately.In this paper,a reasonable simplified model of column boundary conditions is proposed and the key parameters affecting the anti-explosion performance of columns are analyzed.On this basis,the continuous collapse evaluation of the pre-stressed assembled concrete frame structure is carried out and the key parameters affecting its collapse performance are analyzed.The main research work and research results are as follows:(1)The finite element model of prestressed assembly concrete space joints is established by ANSYS/LS-DYNA software.Compared with the test,the correctness of material selection and parameter setting of the model is verified.(2)According to the characteristics of the pre-stressed assembled concrete frame structure,the theoretical calculation method of restraint stiffness of the top of the column is put forward,and a simplified model for failure analysis of the pre-stressed assembled concrete frame column under explosive load is established.Based on the simplified model,the key factors affecting the anti-explosive performance of the prestressed assembled concrete frame column are studied through parameter analysis.The results show that The axial compression ratio has a great influence on the residual displacement of the column,and the strength grade of concrete has a great influence on the maximum displacement of the column.The local stirrup encryption can meet the explosion resistance design requirements of the column.(3)The dynamic response and anti-progressive collapse performance of the plane frame structure of the prestressed assembly concrete structure under blast load are studied by using the non-linear dynamic analysis method,and compared with the castin-place structure,the similarities and differences of the two progressive collapse mechanisms are analyzed.The resistance of the two structures is the same in the beam mechanism stage,and the prestressed assembly structure in the catenary mechanism stage is superior to the cast-in-place structure.(4)Based on the simplified model for failure analysis of prestressed assembly concrete frame columns under blast load and considering the boundary conditions of columns,a simplified model for calculating collapse displacement of prestressed assembly concrete frame structures under blast load is established.An evaluation method for collapse resistance of prestressed assembly concrete frame structures under blast load is proposed.