Design Study Of Space Tubular Structure Under Design-build Mode

In recent years,with the increasing demand for architectural aesthetic,in order to reflect the three-dimensional effect of buildings,there had built a lot of special-shaped,innovative and complex large-span space steel structures.The pipe truss structures,because of the characteristics of simple manufacture,lightweight property,high material utilization,are accepted by more and more structural engineers.At the same time,according to the statistics of scholars,at the present stage of the accident events,nearly eight layers occurred in the construction phase,the main reason was that the structures at the design stage did not consider the impact of the construction phase and the period might be significant weak links,the design side and the construction side were not effectively linked.Based on the design-construction general contracting pattern,this paper took SAP2000 structural analysis and design software and took a typical large-span space pipe truss structure as an example,from the perspective of structural engineering,analyzed the design phase and the construction phase of the whole process for the engineering case.In the stage of design,the site conditions of the project were assumed to be related to the seismic grade,wind load,thermal action,dead and live load.There had been considered analysis of static calculation,analysis of natural vibration characteristics,analysis of seismic action and performance-based design of buildings and so on.The results of the above analysis showed that the truss element transforms the complex stress state of the curved beam into a simple tensile and compressive stress state of the truss bar,and the force flow is clear and the rod is mainly subjected to axial force.Secondly,for this kind of large-span cantilever pipe truss structure,the vertical rigidity of the structure is weak and the structure itself has torsional coupling effect.Finally,under the action of earthquake,the project was calculated by the vibration response spectrum method and the elastic time history analysis method,and satisfied the seismic performance target of the small earthquake elastic and the important components of medium earthquake did not yield.In the stage of construction,the temporary state of the structure is not considered in the original design.With the development of every step of the construction,structure analysis of each construction phase is a linear analysis,but for the whole construction process,the quality,stiffness,load and boundary conditions of the structure are constantly changing,each analysis based on the prev ious analysis results,so the construction stage analysis is a special type of nonlinear static analysis.According to the load conditions which may occur in the construction stage,the hoisting analysis,load analysis and unloading analysis are carried ou t.Through the analysis of the hoisting of the component unit,the suitable hanging point was selected,and there was no excessive deformation in the process.Secondly,two kinds of loading schemes were selected to simulate the loading process,and the pro cess and results were analyzed.In the case of both the strength and the plan of the minimum deformation was the final loading scheme.At last,the unloading of the frame was the key problem of the project,the unloading process was the process of structural system conversion,and the redistribution of the internal force of the structure was very important to the final shape of the structure.Through the analysis and comparison of six unloading schemes and the results of the deformation of the unloading sta ge and the change of the reaction value of the support,the equivalent unloading method was selected as the final unloading scheme.