Study On Bond Slip Performance Of Aluminium Alloy-concrete Interface Based On Double Shear Test

At present,FRP and steel plates are commonly used as reinforcing materials for the construction industry in the field of civil engineering in China.However,both of these materials have their limitations.FRP is a brittle material and its failure is without any sign,and steel plate has poor ability to resist corrosion.Compared with steel material,structural aluminum alloy have the advantages of corrosion resistance,low density,and easy molding,and have better ductility than FRP.so this paper intends to conduct experiment to research bond-slip performance of the aluminum alloy–concrete interface,and demonstrate the feasibility of using aluminum alloy plates as externally bonded strengthening material for reinforced concrete members,the main research content as follows:1?In order to achieve the purpose of testing,a double shear test loading apparatus was designed;In order to guarantee the precise centering of two concrete test blocks and the accurate positioning of the aluminum alloy plate,a positioning mold was designed;In order to avoid the phenomenon of tension eccentricity at the greatest extent during loading,a universal joint device was designed.2?45 specimens were fabricated to suffer to double shear force,the parameters including concrete strength grade?aluminum alloy?AA?plate bond length?width ratio of AA plate and concrete and AA surface roughness that how to influence interfacial bond behavior were analysed,and bonding failure mechanism?failure mode and interfacial debonding bearing capacity were studied under those parameters,The strain distribution law on the aluminum plate surface along the bond length direction,the evolution law of the bond shear stress and the load-slip evolution law at the loading end were obtained.The results show that the stress process of the interface is gradually transferred from the loading end to the free end,and according to the stress transfer area,all specimens have an effective bond length value,beyond which the stress is no longer transmitted.The shorter bond length,the smaller bond width,and the lower concrete strength grade,the faster the stress transfer speed at the specimen interface.Aluminium plate surface treatment had no substantial effect on the improvement of strain distribution and bearing capacity of specimens.the strength grade of concrete was increased,and the width of bond was increased,which could increase the bond stiffness of interface.The bond length has no great influence on the interface bond stiffness,but it can increase the ductility of specimens,for specimens with different surface roughness,the surface bond stiffness of N type is the largest,followed by G type,and B type.3?A comparison between experimental bond-slip curve of aluminum alloy-concrete interface with that of FRP bond-slip models of Nakaba et al.revealed that Nakaba models can be used to predict the bond-slip performance of aluminum alloy plates attached to concrete surfaces at the ascending branch,however,there are different degrees of deviation at the descending branch.Finally,a modified Nakaba model that considering the ratio of bond width between aluminum alloy plate and concrete was established,and expression of two important control parameters?_maxand ₀s were given,which be found that has good agreement with bond-slip experimental curve with different bond widths.