Study Of Bonding Slip Mechanism Between Aluminum Alloy Bars And ECC

Engineered Cementitious Composite(ECC)has characteristics such as ultra-high toughness and tensile strain hardening.Aluminum alloy reinforcement is a material with high tensile strength and good corrosion resistance.Compared with concrete,ECC has better deformation ability and good deformation coordination ability between ECC and aluminum alloy reinforcement.Aluminum alloy reinforcement ECC structure can achieve smaller crack width and higher durability,and has good application prospects.At present,there is relatively little research on the mechanism and performance of bond slip between aluminum alloy reinforcement and ECC.Therefore,in order to analyze the basic characteristics of bond slip between aluminum alloy reinforcement and ECC and the influencing factors of bond slip,this article combines experimental methods to conduct experimental research on the bond slip performance between aluminum alloy reinforcement and ECC.The Control variates was used to design 15 groups of aluminum alloy reinforcement ECC specimens for bond slip test.Based on the test results,the effects of aluminum alloy reinforcement anchorage length,aluminum alloy reinforcement diameter,PVA fiber content and ECC protective layer thickness on the failure mode and bond stress of aluminum alloy reinforcement ECC specimens were analyzed.The results indicate that the main factors affecting the bonding stress of aluminum alloy reinforcement ECC specimens are the anchoring length of aluminum alloy reinforcement,the diameter of aluminum alloy reinforcement,and the amount of PVA fiber added.The thickness of ECC protective layer has little effect on the bonding stress.Based on the experimental results,the load slip curves of aluminum alloy reinforcement ECC specimens at the loading and free ends are proposed,and the characteristics and influencing factors of the load slip curve are studied.By analyzing the strain distribution of aluminum alloy bars,the distribution pattern of strain along the anchorage length of aluminum alloy bars under different loads is obtained.Based on experimental data and regression analysis,a formula for calculating the bonding strength of aluminum alloy reinforcement ECC components was established.The results showed that the established formula can be used for calculating the bonding stress of aluminum alloy reinforcement ECC components.By analyzing the bond stress slip curves of each specimen,a bond stress slip constitutive relationship for aluminum alloy reinforcement ECC specimens is proposed.Compared with experimental results,it is shown that the bond stress slip constitutive relationship proposed in this paper can accurately describe the bond slip performance of aluminum alloy reinforcement ECC specimens.According to the bond strength calculation formula of aluminum alloy reinforcement ECC,the reliability analysis of the anchoring length of aluminum alloy reinforcement in ECC components is conducted using the center point method.At the same time,based on the statistical parameters of aluminum alloy reinforcement and ECC mechanical properties,the basic anchoring length of aluminum alloy reinforcement in the component is calculated.The anchoring length of aluminum alloy reinforcement obtained through different methods of analysis and calculation provides recommendations for the anchoring length of aluminum alloy reinforcement applicable to ECC components.The finite element model of aluminum alloy reinforcement-ECC specimen was established by ABAQUS finite element analysis software,and the simulation results of finite element analysis were compared with the results of drawing test.The results show that the free end load-slip curve calculated by the finite element model is in good agreement with the test curve,and the overall development trend of the curve is the same.