Study On Dynamic Response Of Concrete-filled Steel Tubular Columns Confined By FRP Under Axial Compression Under Explosion Load

In the building structure,whether the load-bearing column is safe or not has a great influence on the stability of the whole building structure.In today’s society,terrorist explosion activities and accidental explosion accidents occur from time to time,which pose a great threat to the safety of the load-bearing column,therefore,it is a subject of great practical significance to study its ability to resist explosion impact.Fiber Reinforced Polymer/Plastic(FRP)confined concrete-filled steel tubular column is a kind of composite structure which wraps FRP on the outer surface of concrete-filled steel tubular column in a specific way.This composite structure can not only improve the corrosion resistance of concrete-filled steel tubular column,enhance the working performance of concrete-filled steel tubular column,and save the use of steel,but also solve the problem of insufficient ductility of FRP through the advantages of good plastic toughness of concrete-filled steel tubular.In this paper,the FRP confined concrete-filled steel tubular column under axial compression was taken as the research object,and its dynamic characteristics under explosion load were studied and analyzed.The main research contents and achievements are as follows:(1)The finite element model of FRP confined concrete-filled steel tubular columns under axial compression under explosion impact load was established by using the simulation dynamic analysis software,and the existing explosion tests of concrete-filled steel tubular columns were numerically simulated,and the numerical simulation results were compared with the test results,which verified the rationality of the selected material model and parameters,the way of applying axial force and the finite element analysis model.(2)The dynamic response of typical FRP confined CFST columns under axial compression was analyzed,such as failure mode,strain distribution of CFRP,mid-span displacement and so on.In addition,the horizontal displacement of columns with different axial compression ratio,slenderness ratio,FRP bonding methods and FRP types was analyzed by using the parametric analysis method,and studied the influence of different influencing factors on the anti-explosion ability of columns.It is concluded that when the axial compression ratio was no more than 0.5,the existence of axial pressure could improve the anti-detonation performance of the specimens,however,when the axial compression ratio was more than 0.5,the existence of axial pressure greatly reduced the anti-detonation performance of the specimens.With the increase of slenderness ratio,the mid-span displacement of the specimens increased,and the blast resistant capacity decreased.Pasting FRP could improve the anti-explosion performance of the specimens,and the specimens locally pasted FRP with reasonable design could achieve the constraint effect with those fully pasted.Under the condition that other parameters remained unchanged,pasting CFRP was more effective in improving the blast resistant capacity of specimens than pasting GFRP.It will provide reference for the anti-explosion design of such members in future projects.(3)The combined strength,the combined elastic modulus and the ultimate bending moment of concrete-filled steel tubular column members confined by FRP under axial compression were solved,and the dynamic response of typical member under explosion impact in numerical simulation was theoretically solved by using the equivalent single-degree-of-freedom system considering axial force.At the same time,the theoretical calculation results were compared with the numerical simulation results,and the purpose of mutual verification was achieved.