Study On The Flexural Performance Of Reinforced Concrete Beams Strengthened By Prestressed Aluminum Alloy Wire

At present, the external prestressing mainly uses the prestressed standand the high strengthsteel wire as the prestressing tendons for structural reinforcement.Because of the limitation of the material, steel stands and high strength wires have many disadvantages such as poor corrosion resistance, cold brittleness, poor adaptability in acid or alkaline conditions and low temperature and so on. Moreover, the ductility of the structure will be decreased and mostly brittle failure under the condition of reinforcement. Through the test of high strength aluminum alloy, we find that the ductility of the aluminum alloy is better at the tensile strength, although the ultimate stress is lower than that of the prestressed stand and high strength steel wire. What’s more, the high strength aluminum has more advantages, for example, lower susceptibility in low temperature than steel, lighter quality and corrosion resistance. It can be used as a material for external prestressing in acid-base environments, cold temperature and other special conditions. In view of the problems existing in the external prestressing of the prestressed standand high-strength steel wire, and the advantages of high strength aluminum alloy, the following aspects has been done in this paper:1. Drawing the mechanical properties of high-strength aluminum alloy material, analyzing the stress- strain curve and establishing high strength aluminum alloy constitutive model formula, by the material performance testing of high strength aluminum alloy bars.2. Considering the secondary effect of externally prestressed tendons, analyzing variation of externally tendons of the high strength aluminum alloy, and establishing the stress increment formula of the aluminum alloy reinforced tendon on the basis of minimum deformation energy principle. Moreover, the factors that affect the loss of external prestressing are systematically analyzed, and the calculation formula of the loss of the external prestressing is given.3. Analyzing the behavior of the concrete beam strengthened by the external prestressed high strength aluminum alloy bars, and establishing the formula of the ultimate bearing capacity.Besides, Analyzing the performance of normal section of the concrete beams strengthened by the external prestressed high strength aluminum alloy bars without taking into the effect of the secondary effect, and establishing the formula of the ultimate bearing capacity of normal section. According to the previous, the formula for calculating the reinforcement of the aluminum alloy tendons is deduced.4. Using ANSYS to analyze the concrete beam which is reinforced by external prestressing tendons. The results of the ANSYS and the experiment which is compared, and the accuracy of the ANSYS model is verified. Then, replacing the external prestressed tendons by high strength aluminum alloy bars with the principle of equal section and equalling strength, and analyzing the new models. Compared with the beam which is reinforced by the external prestressed high strength steel wire, the improvement of the ultimate bearing capacity of the beam which is reinforced by the aluminum with the same section area is less, but the ductility of the concrete beam is improved. In the same strength of the aluminum alloy, the bearing capacity and the ductility of concrete beams can be improved correspondingly.