Analysis Of The Key Problems On The Design Of A Large Span Spatial Steel Structure

In recent decades, with the rapid development of the large-span space steel structure, its spatial performance and seismic behavior needed to be researched deeply. In this paper, based on the background of greenhouse design of a botanical garden, employing the advantage of FEM software SAP2000 and ANSYS, the static performance, stability and seismic behavior of the space steel structure were analyzed systematical y. The main researches and relevant conclusions are as follows:(1)Based the review literatures of the development of large-span space steel structure and research status, the basic information, structural layout, load value and load cases combination were introduced in detail, and the key problem in the engineering design was summarized.(2)The flow field around the building and the wind pressure distribution on the building were researched with the method of numerical wind tunnel, and the difference was discussed through the comparison with the results of wind tunnel tests. Based on all above, the wind distribution around the building was discussed in detail. The results indicated that the outcome of two methods coincided well, but result obtained from the numerical method was lower than that from wind tunnel test in general. Consequently, for the sake of safety, the design of this structure should be accordance with wind tunnel test and the numerical method could be s considered as reference.(3)The influence caused by internal stress distribution under main load cases, eigenvalue buckling analysis of whole structure, second-order elastic-plastic capacity of stability, and the initial geometric imperfections induced by consistent mode imperfection method was calculated. The results showed that the internal stress mainly distributed over and the stress of structure was smal er overall, and the maximum deformation could meet the requirement of L/400; the whole structure was not sensitive to the initial geometric imperfections. Furthermore, the determination of column design length was discussed and the proposed value of coefficient of effective length of column was presented.(4)The self-vibration characteristics was analyzed with SAP2000 software; and through the combination of response spectrum analysis and time-history analysis, the displacement of controlling point, stress of key component under principal directional earthquake were navigated; besides, the displacement and stress response of input seismic excitation in XZ and YZ direction was studied; meanwhile, the comparison of results of response spectrum analysis and time-history analysis was performed and the reason for the difference was analyzed. The results demonstrated that the basic frequency was small and local vibration did not occur in the first ten modes, and the vertical earthquake imposed slight influence on the structure, indicating that although the structure was flexible, its integrity was excel ent. The first 80 mode vibration could meet the requirement of Seismic Code, and the maximum story drift under unidirection elastic seismic input could meet the demand of drift limit value; the outcome obtained from response spectrum analysis exceeded that from time-history analysis, which was caused by the combination of envelop values, which could not achieved the maximum simultaneously, of structural response of spectral analysis.