Experimental Study On Bond Behavior Between RC Beam And Steel Plate Under Impact Loading

Because of its convenient construction and its ability to greatly increase the bearing capacity of the structure without changing its structural appearance,the technology of externally bonded steel plates has been widely used in existing bridge reinforcements.However,in the actual reinforcement project,the debonding failure tends to occur at the end of the steel plate and the concrete adhesive interface,so that the strength of the steel plate cannot be fully utilized.At the same time,such damage is often brittle,and it is necessary to avoid in the actual construction.In this paper,three-point loading test method was used to test RC beams strengthened with steel plates under static loading and impact loading tests.The mechanical properties and interface debonding modes of RC beams strengthened with steel plates were tested and studied.The main research contents are as follows:1.Three-point static loading test of RC beams strengthened with steel plates is implemented on a static load tester.The main parameters of the test were the length of the steel plate,the thickness of the steel plate,the thickness of the adhesive layer and the anchoring form,including the comparative tests of 15 reinforced beams and 1 unstrengthened.The failure modes,the load-deflection curve,the strain of the steel bar and the externally bonded steel plate were obtained.The test results show that the external steel plate reinforcement can effectively improve the stiffness and ultimate bearing capacity of the beam,but different parameters significantly affect reinforcement effect,failure mode and the stress distribution of the bond layer are more significant.2.Three-point loading impact test of RC beams strengthened with steel plates is implemented on a drop hammer tester.The main parameters of the test and the design of the test specimen are consistent with the static load test.The failure mode,load and displacement history curves,time history curve of the steel plate and steel bar strain are obtained.The test results show that the external adhesive steel plate can enhance the beam body.Impact resistance,but different parameters significantly affect the reinforcement effect,failure mode,and stress distribution of the bond layer.3.Considering the bonding behavior between steel plate and concrete,a finite element model of steel plate reinforced RC beam is established.The results show that the established finite element model can effectively simulate the mechanical behavior of the prestressed RC beam under impact loading and the debonding effect of the steel plate.4.By comparing the testexperimental results of static load and impact load,the results show that although the maximum shear stress of the tip can be increased correspondingly under the impact load,the violent strain change makes the external adhesive steel plate easier to debond.5.The expansion analysis of the verified finite element model is carried out,and the shear stress intensity corresponding to the adhesive layer with different parameters is discussed,which provides a theoretical basis for the actual strengthening process.