Numerical Simulation Study Of CFRP-Steel Composite Structure Under Explosion Load

In recent years,there have been numerous cases of regional conflicts and terrorist attacks internationally,especially targeting landmark bridges.Additionally,explosions during energy transportation or storage pose a constant threat to the safety of various bridge types and the people around them.Steel pipe columns,widely employed in bridge superstructures,are highly regarded for their ability to effectively reduce the overall weight of the structure while maintaining exceptional strength.However,these columns are susceptible to being targeted by explosive terrorist attacks and are also vulnerable to explosions related to energy transportation,given their exposure to the air.Currently,there is a lack of research and exploration regarding the explosion load on steel tube structure bridges and specific technical specifications.CFRP(Carbon Fiber Reinforced Polymer)materials exhibit excellent properties such as light weight and high strength,making them highly valuable in early design and subsequent reinforcement maintenance of bridge engineering.Therefore,this paper focuses on the research object of composite structures,specifically the steel tube structure reinforced by CFRP.The study aims to explore the dynamic response of the steel tube under explosion loads through finite element analysis.The main research work and achievements are as follows:(1)Simplifying the blast wave load generated by explosions,the motion equation of the simplified system under axial force and explosion load is considered based on the theory of an equivalent single degree of freedom system(ESDOF).By introducing a conversion coefficient,a two-stage resistance force solution method suitable for CFRP-steel composite structures is derived.(2)Using the explicit dynamic analysis module of the finite element software Abaqus,a constitutive model considering material and geometric nonlinearity is selected after analyzing the selection of geometric element types and achieving mesh convergence.The material is assigned to the Euler area,and the air area boundaries without reflection are defined.The JWL equation of TNT is fitted,and a CEL model considering shock wave transfer in air is established.In contrast,a CONWEP model is established,which disregards the air effect and fixes the TNT parameters.The accuracy and reliability of the CEL finite element model for explosion analysis are verified through experimental results.(3)The dynamic response of the CFRP-steel composite structure under explosion loads is analyzed,including the displacement of measurement points,peak displacement values,time nodes,and the development of plasticity.Through parameter analysis and in conjunction with engineering reinforcement practices,the dynamic response of the composite structure under different parameters is explored.The study concludes that CFRP reinforcement significantly reduces the impact of explosion loads on composite structures.(4)Building upon existing damage evaluation criteria,a damage critical value is set for finite element simulation trial calculations.The stress and energy values are recorded when the measuring point of the structure reaches the damage critical displacement.By fitting the S-E curve,the work safety state of the structure is evaluated,and a reference damage evaluation method is established.Additionally,optimal reinforcement suggestions are proposed for various reinforcement requirements based on explosion-proof engineering design and finite element analysis results.