A Study On Cooperative Work Between A Long-Span Roof And The Supporting Structures

With the development of the economy and the higher pursuit of people for material and cultural life, more and more large span stadiums and exhibition halls have been built.Upper structure of the project is generally large span steel roof and lower structure adopts reinforced concrete structure. Due to the division of structural design, the upper structure and lower support systems are often considered separately and using fixed hinge support to simulate the supporting of truss structure, it’s obviously improper.The resulting result will be unreliable in structure safety or huge waste in economic. A project is taken as a research object in this article and the finite element analysis software Midas/gen is used for the analysis of three kinds of simplified model (hinged support, elastic support, and support taking into account of the mass and stiffness of lower supporting structure), and the variation of axial force of the upper and lower chords of the truss and the vertical displacement of the node with span are concluded and the results are compared with the overall model. Mode decomposition response spectrum method is used for the whole structure to study the influence of variation of lower support stiffness and different damping ratio on the seismic performance of the whole structure. The results show that the influence of the interaction working between the roof and lower supporting structure at the combination of static load condition is limited, the stiffness of lower supporting structure have a great influence on dynamic response of truss structure, so it can not be simply to simplify the lower support as the hinged support and the elastic support, otherwise the design is unsafe.Owing to the different material’s damp of composite structure, "group of damping ratio" method is used to input in the calculation, and get the overall comprehensive equivalent damping ratio. The safety of the structure analysis can be further improved by determining the appropriate structural damping ratio.