Study Of Dynamic Properties For Buckling Restrained Brace And Application In The Steel Arch Structure

Buckling Restrained Brace (BRB) yield but not buckling under axial compression loads, performs good hysteretic properties and energy dissipation. Now it is applied to new buildings and reinforcement of existing buildings. However, all core technologies of BRB are private; the core components of BRB generally use low-yield point of steel, it has not yet been produced in China; based on the current principle of BRB, researchers design this braces by domestic steel, but lack of a large number of system testing and research; in addition, the main research of BRB focus on the framework and less on the large-span structure, the applied research on the large-span steel arch structure is still not found. Therefore, based on the research by domestic and international, this paper study the mechanical properties of BRB using theoretical analysis and experimental methods, conduct a comprehensive analysis in the large-span steel arch structure the first, perform parametric analysis. Four parts are study as follows: (1) The mechanical properties of BRB is comprehensive analyzed. The global stability for pure steel and concrete type of BRB is studied, the number of lateral stiffness and requirements of BRB are obtained with the calculation formula; compare the stiffness requirements of outer tube for two different types BRB; by use of MATLAB software, the influence of stiffness and length of stiffen regions under the critical load for core member are given; the stability of the formula are given, in which the initial geometric defect, width-to-thickness ratio, slenderness ratio; boundary conditions are considered; the hysteretic curve of the simulation equation is conducted; the dynamic stability is analyzed combined with the components that used in the experiment, the results shown that the bigger of lateral rigidity, the better of its dynamic stability. In additional, reliability problem of BRB is discussed. (2) The FEM simulation of BRB. By ANSYS software, 17 entities finite element model is selected, under pure steel and concrete type of BRB, the hysteretic curve and load-displacement curve of axial compression are investigated; the mechanical properties of BRB under different parameters, including the number of lateral braces, the stiffness of outer tube, the stiffness of stiffen regions, width-to-thickness ratio, slenderness ratio. Comparison with the test results, it shows that theoretical analysis and experimental has the same tendency, but there are certain differences in values. (3) The experiment research. Four pure steel and one concrete components were selected, the hysteretic curve and load-displacement curve of axial compression are researched, the results of theoretical analysis and ANSYS analysis is compared, it is showed that generally difficult to achieve the design requirements for the single point-support of BRB because of stiffiiess degradation, however, the continuous support of BRB has a good hysteretic performance and better energy dissipation, also verified the construction of concrete BRB used in this test meet the requirements. (4) the vibration analysis in large-span steel arch structure with BRB. Under 3-D seismic excited, the effect of different arrangement of BRB, seismic fortification intensity, seismic waves, height-span ratio, length-width ratio, boundary conditions, substructure influence are studied. The results showed it has some influence on the vibration of large-span steel arch structure with BRB, but its effect subject to a greater impact on these parameters.