| The performance of steel-concrete composite columns is excellent,but for the bridge structure exposed to the natural environment for a long time,the deterioration and even premature failure of the structure performance caused by steel corrosion are generally important problems.In order to overcome this problem,in recent years,scholars from all over the world have shown great interest in resin-based fiber reinforced polymer with excellent corrosion resistance,The application of FRP in the field of civil engineering reinforcement and new structure is studied.One of the most potential directions is to optimize the combination of FRP and traditional building materials(such as concrete and steel)to form a new type of composite component and structure with economic,corrosion-resistant and seismic performance.In order to give full play to the properties of FRP,steel and concrete,a new type of steel reinforced concrete composite column with cruciform steel ribs is proposed in this paper.The new composite column has the following advantages: 1)FRP pipe has good corrosion resistance,which makes the composite column can be used in corrosion and special adverse environment,and FRP pipe can be used as the formwork for pouring concrete in construction projects,saving the cost of formwork;2)FRP pipe and cross shaped steel bone can form more effective double constraint on core concrete,improving the strength and ductility of concrete;3)The built-in steel bar can be used as the longitudinal load-bearing steel bar and can be easily connected with other components to form a structure.The external displacement of the profile steel flange can give full play to the bending performance of the steel bar.At the same time,the two-way shear and bending performance of the cross section of the steel bar are the same,avoiding the strong and weak axis problem of the column section,and enhancing the stress and seismic performance of the composite column.At present,the research on this new type of composite column is still in its infancy,and only some scholars have studied its axial compression performance.In order to investigate the mechanical properties of the new composite column,the experimental research and theoretical analysis on the unidirectional eccentric compression performance of FRP tube confined cruciform steel reinforced concrete column are carried out in this paper.The main research contents are as follows:(1)In this paper,nine FRP tube confined cross-section steel reinforced concrete columns were tested under one-way biasing load.The failure mechanism and the influence of failure mode,ductility,stability factor and bearing capacity of the columns were investigated.The results show that the failure of the columns is obvious under biasing load Obviously,the bearing capacity declines slowly after the ultimate load,showing better ductility performance;slenderness ratio and eccentricity have great influence on the ultimate bearing capacity and stiffness of the component,and the restraint effect of FRP pipe on concrete decreases with the increase of slenderness ratio and eccentricity;the upper and lower parts of the measured lateral deflection curve of the component are basically symmetrical along the column height direction,close to the sine half wave curve;section The strain distribution accords with the plane section assumption.(2)Based on the experimental analysis results,considering the contribution of the double restraint of cross steel and FRP pipe to the improvement of concrete strength,considering the influence of slenderness ratio and eccentricity on the restraint effect,two failure modes of the eccentric column are defined by the ultimate compressive strain of the eccentric column,and the calculation method of the eccentric compressive bearing capacity of the cross steel reinforced concrete column with FRP pipe about bundle is established.The calculation results and the test results are combined.The results were in good agreement. |
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