Experimental Study On Flexural Performance Of RC Beams Reinforced With Anchored Aluminum Plates

Aluminium alloy material has obvious advantages in the field of reinforcement,it is a lightweight,high-strength,corrosion-resistant,low-temperature-resistant material with superior deformation performance,especially suitable for erosion,moisture,cold and other extreme environment.Mechanical anchorage reinforcement has a good fit with aluminium alloy material,using mechanical anchorage to reinforce flexural RC beams can effectively avoid the interface durability problems and early peeling damage phenomenon caused by structural adhesive.Based on this,an experimental study was carried out on the bending performance of RC beams reinforced with anchored aluminium alloy plates,mainly as follows:(1)Four connections methods between aluminum alloy plate and RC beams were concerned,which were external bonded(EB),external bonded and fastened with bolts(EFB),end mechanical fastened(MFE),and uniform mechanical fastened(MFU).The test results showed that there are two types of damage models in the test: the brittle end concrete peeling damage occurred in the EB,and EFB specimens and the span concrete crushing damage occurred in the MFE and MFU specimens with excellent ductility which due to the phenomenon of “load second rise” and “stress hysteresis” of aluminum alloy plate.(2)Further experimental research on end mechanical fastened(MFE)connections method was carried out,the effects of aluminum plate type,thickness of aluminum plate and reinforcement ratio of concrete beam were analyzed.The results indicate that the ultimate load of the specimens was increased by 33.69%～70.19% by using aluminum plate with thickness of 2-8 mm for reinforcement.The improvement increased with the increase of thickness until the thickness of aluminum plate was large enough.The ductility which is decreased with the increase of thickness.of the reinforced specimens was high.At the preload stage,the aluminum plate utilization efficiency is low,and the pre-strengthening stiffness of each reinforced beam is close at different thicknesses.The ultimate load was increased by 92.16%,57.82% and 23.19% for concrete beams with three types of reinforcement rates of 0.47%,1.05% and 1.43%.Therefore,the load carrying capacity of beams with low reinforcement rates was improved more.The loaddeflection curves overlapped to a higher degree when different types of aluminum alloy plates were used for reinforcement,and the reinforced beams had similar force and deformation properties.(3)The results of experimental study on the flexural performance of RC beams strengthened by end anchorage(MFE)show that: the effect of damage on the bearing capacity needs to be considered comprehensively.Under a certain degree of damage,the stress hysteresis effect is relieved,the aluminum alloy plate is utilized more efficiently,and the strengthened beam has higher yield and ultimate strength,but the bearing capacity and ductility of RC beams are reduced under higher levels of damage.(4)The experimental study on the effect of cyclic loading on MFE reinforcement shows that: the load-deflection curve under cyclic loading has a high degree of overlap with the load-deflection curve under monotonic loading,and the law obtained under monotonic loading is still applicable under cyclic loading;the residual strain of aluminum plate is small after unloading to ultimate load.And in practical engineering,the aluminum plate can be removed after unloading for secondary reinforcement.(5)The theoretical models of flexural bearing capacity and deflection of RC beams reinforced by end-anchored aluminum alloy plate established in this paper is in good agreement with the test value,the discreteness of the data is small and the calculation accuracy is high,which can effectively predict the bearing capacity and deflection of the reinforced specimens.(6)The bending performance of RC Beam Strengthened with anchored aluminum alloy plate is simulated and analyzed by finite element software.The finite element analysis results are compared with the test results to verify the accuracy of the finite element model,which lays a foundation for finite element analysis in the future.