In-plane Stable Ultimate Bearing Capacity Of CFST Parabolic Arches Reinforced With CFRP

Concrete filled steel tube(CFST)has a history of more than 100 years,with high bearing capacity,convenient construction and other advantages,has been widely used in bridge structure.With the development of structural technology,the span of steel-concrete arch bridges has been continuously increasing,which requires the use of thick-walled or high-strength steel tubes to provide sufficient lateral restraint for the core concrete,undoubtedly greatly increasing the project cost.At the same time,in coastal areas,saline-alkali areas and cold areas where deicing salt is frequently used,steel tube corrosion of CFST arch bridge is becoming more and more serious,and the durability of the structure is declining,which increases the maintenance cost in the later period and also brings security risks that cannot be ignored.Carbon Fiber Reinforced Plastic(CFRP)is a new material made of carbon fiber and polymeric resin through a certain process.It is widely used in engineering for its high tensile strength,light weight,corrosion resistance and good durability.In order to solve the problems of corrosion and large amount of steel in CFST arch bridge,this paper adopts CFRP to strengthen the structure of CFST arch,and carries out experimental research and finite element simulation on the structure,and completes the following research contents:(1)Three CFRP-reinforced CFST parabolic arches and two CFST parabolic arches were tested for ultimate bearing capacity of in plane stability,and the effects of different CFRP thickness,different CFRP winding modes and steel strength on the ultimate bearing capacity of the specimens were analyzed by using five-point vertical symmetric loading.The test results show that the arch rib specimens are mainly compressed under this load condition,and the failure mode is closely related to the initial defects.Increasing the thickness of CFRP and the strength of steel can improve the ultimate bearing capacity of in plane stability for arch rib specimens,and the bearing capacity of CFRP reinforced by circumferential winding is higher than that of CFRP reinforced by longitudinal winding..(2)Finite element software ABAQUS was used to conduct numerical simulation analysis of arch specimens,fully considering the geometric nonlinearity and material nonlinearity,the influence of CFRP and steel tube on the hoop action of core concrete and the initial defects,and the load-displacement curve of the model were calculated and drawn,and compared with the experimental results.Finally,the reliability of the test results and the correctness of the finite element model were verified.(3)The verified finite element model was used to analyze the effects of steel strength,concrete strength,FRP thickness,CFRP winding angle and steel content on the stable ultimate bearing capacity of CFRP-reinforced CFST.Based on the parametric analysis results and the existing formula for calculating the stability bearing capacity of CFST arch,a calculation method considering the coefficient of FRP hoop was proposed.