Study On Experiment And Design Of FRP/steel Composite Perfobond Shear Connectors

In recent years,reinforced concrete structures have been widely used in civil engineering,but the problem of reinforcement corrosion has become more and more serious,causing huge losses and safety hazards.Fiber Reinforced Polymer(FRP)has gained widespread attention in today’s civil engineering industry due to its advantages of light weight,high strength,corrosion resistance,fatigue resistance and convenience of designing.However,the shortcomings such as poor ductility and low elastic modulus of the material have also been criticized.With full use of the advantages of FRP materials and steel,researchers have made FRP/steel composites.Based on the National Natural Science Foundation of China Youth Science Fund project “The Force Performance Analysis,Test and Design Method of FRP/Steel-Concrete Composite Bridge Beam”,this paper explored the mechanical properties of the new shear connectors for FRP/steel-concrete composite bridge beams-the shear connectors of FRP/ steel composite perfobond shear connectors.The details of the main work are listed as follows:(1)In order to make the pull-out tests,13 FRP/steel composite perfobond shear connectors with different radius of holes,number of holes,diameter and types of rebar,the depth of embedding are designed and fabricated.Considering the influence of different parameters on the ultimate pull-out force of FRP/steel composite perfobond shear connectors,the ultimate pull-out bearing capacity calculation formula and the load-slip constitutive model are obtained.The results show that the aperture diameter,the number of opening holes,the diameter of the rebar and the depth of the embedding can directly improve the ultimate tensile strength of the FRP/steel composite perfobond shear connectors,in which the depth of the embedding influences the ultimate tensile capacity most.(2)Based on finite element analysis software ABAQUS,the nonlinear finite element simulation analysis of the static pull-out test of FRP/steel composite perfobond shear connectors was carried out.The solid element is used to establish the finite element model of the specimen,the corresponding constraint relationship is applied,the corresponding contact relationship is established,the mesh of the important force-receiving parts is refined.Comparing the simulation results with the experimental results,the finite element simulation used ABAQUS shows that the test results are basically consistent with the finite element simulation results.At the same time,to make the theoretical system more completed,other factors that may affect the ultimate tensile strength of the FRP/steel composite perfobond shear connectors were analyzed by ABAQUS.(3)According to the theoretical formula,the slip effect on the FRP/steel-concrete composite beam is studied,and the theoretical formula is derived from the two aspects of the additional deflection and the additional bending moment caused by the slip.After summarizing the experimental analysis,theoretical research and structural requirements of the FRP/steel composite perfobond shear connectors,the simplified design method of FRP/steel composite perfobond shear connectors is put forward,which provides reference of design on the interface of FRP/steel-concrete composite beam.