Ultimate Bearing Capacity And Blast-resistant Characteristics Analysis Of CFRP Confined RPC Filled Steel Tube Columns

Explosion accidents have occurred frequently recently,causing heavy casualties and economic losses,scholars at home and abroad have conducted many studies on the explosion-proof reinforcement of the structure,CFRP confined RPC-filled steel tube columns not only has the advantages of excellent durability and volume stability of the RPC-filled steel tube columns,significant economic benefits,avoiding local instability of the steel pipe,and improving the brittleness of the RPC,but also has good corrosion resistance,fire resistance and seismic performance.At present,there is not much research on the static and dynamic performance of CFRP confined RPC-filled steel tube columns.Therefore,through theoretical calculation analysis and finite element simulation,This article obtains the calculation formula of the axial compression bearing capacity of the CFRP confined RPC-filled steel tube columns,and explores its dynamic response under the explosion impact load.The main contents and conclusions are as follows:(1)Based on the unified strength theory and fully considering the influence of the intermediate principal stress,calculation formula for ultimate bearing capacity of.the CFRP confined RPC-filled steel tube columns is derived and revised by correcting the size effect of the steel tube,selecting the size model for the RPC,and considering the bonding effect between the steel tube and the RPC.By comparing with the experimental data,the correctness of the formula is verified.The effects of intermediate principal stress coefficient,concrete strength improvement coefficient,RPC strength,CFRP layer number,steel tube hoop coefficient and friction coefficient on the bearing capacity of components are explored.(2)The equivalent single-degree-of-freedom analysis method considering the influence of axial force is derived based on the traditional equivalent single-degree-of-freedom system.By simplifying the calculation model and setting the boundary conditions,the resistance function expression and characteristic parameters are obtained.And through comparison,it is found that the existence of axial force will weaken the blast-resistant characteristics of the structure.(3)Derive the combined stiffness and plastic limit bending moment of the CFRP confined RPC-filled steel tube columns,and calculate the dynamic response of the CFRP confined RPC-filled steel tube columns under explosive load by using the derived equivalent single-degree-of-freedom system with considering the axial force.And the calculation steps for the maximum dynamic displacement in the middle of the columns are obtained.The correctness of the theoretical derivation is verified by comparison with the experiment,and the effect of CFRP on the blast-resistant characteristics of components is studied.(4)The finite element software ANSYS/LS-DYNA is used to model the RPC-filled steel tube columns and the CFRP confined RPC-filled steel tube columns,and simulate the dynamic response of the two under the explosion load.Comparing the simulation results of the RPC-filled steel tube columns with the test results,the degradation verifies the correctness of the modeling method.The simulation results of the CFRP confined RPC-filled steel tube columns are compared with the theoretical calculation results,and the two are mutually verified.The influence of the thickness of CFRP,the steel ratio,the axial compression ratio and the proportion distance were analyzed by changing the parameter of the model under blast load.