Explosion Failure Analysis And Anti-explosion Retrofit Of Prestressed Precast Concrete Frame

The joints of prefabricated structural members are connected by splicing,which may cause potential safety hazards.Once the failure occurs at the joints of the prefabricated frame,the whole structure will collapse.At present,the research of prefabricated structures is mainly focused on the seismic field,and the emphasis is to verify the seismic performance of prefabricated frame joints.There are few studies on the resistance to other disasters.The explosion load has the characteristics of short duration and large amplitude,and the damage to the assembled structure may be more serious.In this thesis,the explosion response and reinforcement method of precast prestressed concrete frame with unbonded post-tensioned has been studied.The main research work is as follows:(1)The modeling method and corresponding parameters have been determined.The finite element model of reinforced concrete beam subjected to blast impact load has been established,and the validity of finite element modeling method has been verified by comparing with the experimental results under the same conditions,which lays a foundation for the subsequent research.(2)The general cast-in-place concrete frame model and post-tensioned unbonded prestressed prefabricated concrete frame model have been established.The modeling process has been properly introduced,such as the realization method of prestressed steel strand and the contact of beam-column interface.Through the comparative analysis of the dynamic response and failure modes of the two kinds of frame under the explosion load,the anti-explosion performance of prestressed precast concrete frame has been evaluated.(3)According to the failure characteristics of prestressed precast concrete frame,the reinforcement method of adding connecting steel plates at the side of beam-column joints has been proposed to improve the anti-explosion performance of prestressed precast concrete frame.Steel plate anchorage and steel plate bonding have been considered,and the finite element analysis of the frame with the two reinforcement methods has been carried out,and the simulation results have been compared with the numerical results of the prestressed prefabricated frame.The results show that the reinforcement of beam-column joints with steel plate will result in the expansion of the plastic deformation area,the decrease of the beam end deformation and the decrea se of the failure degree of the precast column top,which will lead to the improvement of the anti-explosion performance of prestressed precast frame.In two kinds of steel plate reinforcement methods,the effect of steel plate anchorage is more obvious.(4)Taking cast-in-place frame as reference,according to the vertical displacement of the beam end and the bending of the column top under the explosion load,an index for evaluating the anti-explosion performance of the frame has been proposed.This index has been used to discuss the influence of related parameters of reinforced members on the anti-explosion performance of the frame.According to the analysis in this thesis,the prestressed precast concrete frame has poor anti-explosion performance,and brittle failure is easy to occur in the joint area under the blast load.The prestressed steel strand does not play an obvious role in anti-explosion.After the failure of beam-column joints,the prestressed steel strand aggravates the failure of the precast column.The steel plate anchorage method can improve the anti-explosion performance of the frame.Under the action of the connection steel plate,the prefabricated frame turns from brittle failure to ductile failure.The number of anchorage bars has the most significant effect on the anti-explosion performance of the frame.