Study On Mechanical Performance Of A Space Grid And Ultra-Long Steel Frame-Brace Integral Structure

Space grid structure,steel frame-brace structure and pipe truss structure have been widely used in the construction because of their good performance,large span,flexible space and diversified forms.At present,the engineering application and theoretical research of space gird and steel frame-brace structure have been quite mature.However,due to the limitation of theory,the design and calculation of the two kinds of structures are usually apart and the synergistic effect is seldom considered,leaving some problems to be solved.This paper summarized the development and trend of space gird,steel frame-brace structure and pipe truss structure and the research of assembly analysis in aspects such as static and seismic analysis,which were the background of the project.Taking Tianjin Wanhui Cultural Square indoor amusement central as the theme,some researches of its overall structure which consisted of space gird,steel frame-brace structure and pipe truss structure had been accomplished as follows.The form-finding of the roof was conducted with the improved numerical inverse hanging method by the MIDAS software.The four schemes of roof structure including single-layer lattice shells,double-reticulated shell,plate space grid and less-curved surfaced grid and the model with or without temperature seam were compared.After optimizing the six columns of the central hall and comparing the H-shaped steel beam model with Circle Tubular Steel Columns with pipe truss structure model of the hall curtain wall,the final structure scheme was determined.Taking the boundary conditions,loads and other factors into account,the static performance of the overall structure was calculated by establishing a 3D finite element model.The static performance was obtained by calculating the internal force and deformation of the structure under six different load conditions.The calculation results showed that the deformation of the overall structure met the requirements of the specifications,the stress level of components was low,and the static response was good.The independent model of five roof trusses and the main frame model were established to compare the deviation with the overall structure.The thermal action was introduced in the thesis,and the mechanical properties of the overall structure under the annual temperature load were studied.The bearing reaction force and displacement were calculated to obtain the influence of temperature on the overall structure.Under load combinations with temperature,the bearing capacity,stress and nodal displacement of the overall structure were all satisfied the design requirements and the effect of non-uniform time-varying temperature on the structure was studied simplistically.The deviation between individual structure and overall structure was compared to emphasize the importance of assembly analysis.The dynamic characteristics of the overall structure were also studied.Firstly,the characteristics and effects of seismic action were briefly introduced.Based on the obtained natural vibration characteristics of structure,the mode decomposition response spectrum analysis and time history analysis were conducted.Then the responses of structure in the X and Y directions were calculated respectively,and the seismic design of the structure was checked.The results showed that the horizontal seismic influence was not obvious.The vibration characteristics of the substructure and the overall structure were compared and the deviation of the seismic response was also compared to emphasize the necessity of assembly analysis.