Experimental And Theoretical Research On FRP-steel Plate Under Static Tension And Cyclic Loading

Fiber Reinforced Polymer(FRP)is widely used in the reinforcement of structures because of its light weight and high strength.However,the brittleness of the strengthened structure is significant,which is not conducive to the earthquake resistance of the structure.In order to improve the strength,ductility and stiffness of a single reinforced material,t he FRP-Steel composite was made by combining the advantages of FRP and steel plate.The static and cyclic tensile tests of FRP-Steel plate were carried out.It mainly includes the following aspects:The static tensile test was carried out on 15 FRP-Steel plates to study the influence of the number of fiber layers,fiber types(CFRP fabric,CFRP plate,and GFRP fabric)and steel plate thickness on the basic mechanical properties of FRP-Steel plates.The results show that: the FRP-Steel plate specimen has a stable post yield stiffness after yielding;with the increase of the number of fiber layers,the fiber fracture load of FRP-Steel plate specimen has a certain linear relationship with the number of fiber layers,and the number of fiber layers has different effects on the ductility of test specimens composed of different fiber types;CFRP fabric,GFRP fabric,and CFRP plate have their own advantages in improving the bearing capacity and ductility of FRP-Steel plate.They should be selected in combination with economic performance in engineering application;When the fiber content is the same,the mechanical properties of FRP-Steel plate specimens increase with the increase of steel plate thickness,but the extent of reinforcement decreases.The two stress-strain relationship models of FRP-Steel plate under static tensile load based on composite material mixing theory are in good agreement with the test results,and the calculation accuracy of model B is higher than that of model A;the calculation result of simplified FRP-Steel plate stress-strain relationship model C has higher accuracy,and the model can be applied to engineering practice under similar working conditions.The static tensile test of FRP-Steel plate is modeled and analyzed by ABAQUS finite element analysis software.The finite element model of FRP-Steel plate under static tensile load is in good agreement with the test curve.The model can provide a numerical model reference for similar working conditions of FRP reinforced steel structure.15 FRP-Steel plate specimens and 3 steel plate specimens were tested by cyclic tensile test.By comparing the results of static tensile test,the degradation mechanism of the overall performance of the two materials under cyclic tensile load was revealed,and the cooperative working mechanism of FRP and steel plate under cyclic load ing was clarified.The results show that the number of cyclic tensile has little effect on the fracture strength and the stiffness after yield ing of FRP-Steel plate,and FRP-Steel plate has smaller residual deformation compared with pure steel plate,which shows that FRP-Steel plate has better recoverability.The resilience model of the stress-strain relationship of FRP-Steel plate under cyclic tensile load is in good agreement with the test results,which shows that the theoretical model can be used to predict the mechanical properties of FRP-Steel plate.