Analysis On The Mechanical Behavior Of Long Span Prestressed Truss Structure

Large span space truss structure has lots advantages of reasonable force, flexible layout, light weight, convenient construction and so on, so it can be widely used in large public buildings. But with the increase of truss span, more weight, cost structure, and the combination of prestressed technology and grid to create a new grid structure first, due to the common work of prestressed cable truss structure and the structure of the force is more complex, especially in the earthquake. As the important public building, the safety of long-span space truss structure should be paid enough attention. Therefore, it is very important to study the mechanical behavior of large-span prestressed space truss.Based on the ordinary large span truss and prestressed cable truss static analysis,modal analysis, seismic response analysis of cable and uniform input prestressed grid multi input seismic response analysis, to explore the structure of static, modal and seismic response of prestressed cable, comparative analysis of the influence of different methods and different initial tensile force of cable truss structure the main contents are:(1) The large span truss structure form and the application and development of prestressed grid application, introduces the layout of prestressing and prestressed cable, introduces the analysis method of structure response under earthquake action.(2) To large span truss structure of 84m * 84m as an example of non prestressed and prestressed structure is analyzed, and a comparative analysis of the different structural form and different influence on the structure of prestressed cable tension rod internal force and deflection of the structure; the ordinary non prestressed grid and its well type cable truss, prestressed the well type cable truss and prestressed cable cross prestressed grid structure modal analysis, analysis of the prestressed cable position and tension value influence on structural stiffness.(3) The time history analysis method, selects the EL-centro wave, Taft wave and Tianjin wave, respectively, of non prestressed truss, prestressed grid and bottom pit type cable winding well type cable truss and prestressed cable cross prestressed grid structure of seismic response analysis of uniform input, the ratio of different grid forms in the same role seismic wave; seismic response analysis of multi point input to the bottom well type prestressed grid and wind cable pit cable prestressed grid,and structure and consistent input were compared.Research shows that: the applied structure has the arch effect of pre tension, not only reduces the member stress, but also reduces the deflection of structure, cable prestress net maximum tensile stress and maximum compressive stress is less than the maximum lateral displacement of grid values decreased, the prestressed cable layout mainly improves the structure of vertical displacement is the deflection of the structure, in good agreement with the existing research results.The applied truss structure stiffness increases prestress, prestressed cables and cable number has great influence on the structure, lower well Bousso and well type of winding cable truss structure static and dynamic performance are very significant;the same stress value, the well type cable to the overall stiffness of the structure to improve slightly better than last quarter and with the increase of well type cable,initial prestress, the structure stiffness increases slightly. Well type in ground cable chord rod peak internal force under the action of multi point input are larger than the uniform input, traveling wave effect coefficient is greater than 1, between the different seismic wave traveling wave effect coefficient difference, affect the same seismic wave on the structure of the upper and lower chords are basically the same.