Investigation On Shape-state Optimization And Vertical Seismic Design Method Of Large-span Truss String Structure

Large-span tension structure are extensively used in china now, because of stress fit distribution, large stiffness, light weight, easily making and installing, such as truss(beam) string structure. On the base of data of designing and pre-stress stretching execution of Guangzhou International Convention & Exhibition Center, analyzed all acquired data about truss(beam) string structure , generalized effect of pre-stress on it , at the same time, a method of truss string structure designing is presented in this paper. Truss string structure designing include two steps, shape design(initial shape) and stiffness design, it decreased designing variables and well satisfied shape-state requirement. It is main investigating shape-state optimization and vertical seismic design method of large-span truss string structure in this paper.It is brought forward that shape-state optimization method of truss string structure. First adopt structure discrete method, truss string structure should be divided into truss, string, strut substructure, every substructure has its optimization model. In order to assure coordination, transmitting deform parameter adopted transfer matrix method. This optimization method main is shape optimization, so it is very important that applicability of acquired results, in order to assure results are expectant and meet effective demand, add CAD assistance design, ensured controllability and predictability of calculation results. Meanwhile, shape-state optimization model of truss string structure is founded, and advanced optimization algorithm is adopted, such as genetic algorithm.Optimization model of truss substructure is created, arch axial line shape optimization design of it is studied in this paper, many strut design method are presented through researching of strut, deepgoing analyzed affect factors of truss and strut. Optimization design method of string force, simplify computing method of string force is derived, and analyzedits affect factors. It is adopted that shape-state optimization method of truss string structure on practical structure, results compared with practical truss string structure, effectiveness is verified of established optimization method in this paper. It is studied that affect of pre-stress and geometric large deformation adopting nonlinear analysis method, ultimate bearing capacity and stability are also studied.It is studied that natural frequency, vibration mode and influencing factor of large-span truss string structure. Analyzed by time history method and response spectrum method on 60m, 80m, 100m, 125m, 150m span model, it is got that maximal seismic internal force factor and distribution of truss string structure under small earthquake and large earthquake, structure response difference under different seismic wave, results' difference of time history method and response spectrum method, influence of span on seismic response, change law of deflection, influence of cable slackness etc. It is given that seismic internal force calculation sketch and relative parameter of truss string structure under earthquake.It is got that equivalence vertical seismic load and distribution law of seismic internal force, through statistical analysis of calculated results adopted much seismic wave input, and compared with results got by response spectrum method. Against with seismic design standard, adoption two stage design method, it is studied that value and distribution of seismic load and seismic internal force, and equivalence vertical seismic load of different yard condition is also studied. It is the results that equivalence vertical seismic load distribution is triangle(medium span large, couple of end small), number value related on yard condition.New method of fit design and calculate equivalence vertical seismic load of truss string structure is presented through studying shape-state optimization and seismic response. Investigation main problem of large-span truss string structure, the conclusion also could be referred by other large-span structure.