Research On Mechanical Properties Of Self-centering Brace With SMA And Low-friction

Although the traditional brace can improve the bearing capacity and lateral stiffness of the structure,the residual deformation after the earthquake is large,resulting in high maintenance costs.A new type of Self-centering Brace with SMA and Low-friction is proposed,which can effectively reduce the residual deformation of the structure after earthquake.The brace has good hysteretic performance under cyclic displacement loading,and the residual deformation is small.By changing the important mechanical parameters related to the brace,the energy dissipation reduction performance of the brace can be adjusted to reach the target value.The mechanical properties of the brace are analyzed in detail by means of experimental study and finite element analysis.As a result,the design theory of support is proposed.The main contents are as follows:(1)A new Self-centering Brace with SMA and Low-friction is proposed and its basic structure,working principle,processing process and assembly process are introduced in detail.The material properties of SMA wire were tested and the constitutive data of SMA were extracted,which provided the basis for the subsequent design of the brace.A quasi-static test was carried out on the brace.The results show that under cyclic loading,the brace shows a stable hysteretic curve with small residual deformation;by changing the cross-section of SMA wire in the brace,the torque value of sliding bolt and the pre-tension of SMA,the energy dissipation reset capacity of the brace can be significantly affected.(2)The finite element analysis model was established according to the specific situation of the test.The finite element analysis results were compared with the test results in the hysteretic curve,skeleton curve and stress changes to verify the reliability of the finite element analysis method.Four groups of 10 finite element analysis models were designed to analyze the influence of the cross-section of SMA wire,friction coefficient of friction element,length of SMA and bolt preload of sliding bolt on the mechanical properties of brace.The results show that the finite element results are in agreement with the experimental results.The cross-section of SMA wire,friction coefficient and bolt preload have great influence on the energy dissipation reset ability of the brace.When the brace displacement is within the maximum strain range of SMA,the length of SMA has no significant influence on the mechanical properties of the brace.(3)The superposition principle and theoretical derivation are used to analyze the important characteristic values of the self-centering brace mechanical model in detail,and then the design theory of the self-centering brace is summarized.The results of design theory were compared with the experimental results and finite element analysis results.The results show that the calculated results of the design theory are in agreement with the experimental results and the finite element results,which verifies the reliability and feasibility of the proposed design theory.