Finite Element Analysis Of CFRP Strengthened Compression Round Steel Pipe Column Considering The Adhesive Layer Effect

CFRP materials have attracted more and more attention in the field of bridge engineering due to its excellent performance.Nowadays,the research on reinforced concrete with CFRP materials at home and abroad has become mature,but the research on the improvement of compression performance and stability of reinforced steel pipe columns with CFRP materials still has deficiencies.And so far,there is no relatively perfect steel structure reinforcement design code including CFRP material reinforcement.Therefore,it is important to study the properties and influencing factors for compression round steel pipe bar with the CFRP materials reinforced by means of the finite element analysis.The specific research of this paper is as follows:(1)The finite element software Abaqus is used to establish the finite element model of unreinforced round steel pipe column.During building models,the selection of the constitutive relation for steel,the introduction of initial defects and the application of solving nonlinear problems are emphasized.And through the test results in our group,it is proved that the nonlinear finite element model is reasonable.(2)This paper suggests that using cohesive-force model to analyze adhesive layer in reinforced components.And three types of models which are steel pipe-CFRP,steel pipe-composite material and steel pipe – adhesive layer – CFRP models were established,through the test results in our group,it is proved that the method to consider the adhesive layer is reasonable.In addiation,the adhesive layer’s mechanical behavior during reinforcement of CFRP is proposed based on the assumption of uniform adhesive layer.And the damage condition of the adhesive layer and the reinforcement mechanism of the round steel pipe column with CFRP reinforcement during the stress process are analyzed.(3)After fully understanding the mechanism of round steel pipe with CFRP reinforcement under considering the effect of adhesive layer,this paper focuses on the effect of CFRP mode,number of CFRP layers,ratio,initial bending and eccentricity on the reinforcement effect.(4)Designing the orthogonal test to investigate the influence level of the number of CFRP layers,the ratio and the eccentricity on the compression bearing capacity of round steel pipe with CFRP reinforcement.The theoretical calculation formula of the stable bearing capacity of the compressed round steel string strengthened by CFRP is established,and the correction coefficient considering the influence of many factors on the reinforcement effect is introduced into the calculation formula.Finally,according to the data fitting,revised calculation formula of bearing capacity of compressed round steel pipe column strengthened by CFRP is obtained.