Optimization And Analysis On Large-Span Roof System Of High-Rise Building

In this paper,it takes a large-span high-rise frame shear wall structure as engineering background. First, according to the roof form adopted in the engineering design schemes for further selection and optimization. Meanwhile, the paper analyze the elastic seismic performance under frequent earthquake and the elastoplastic seismic performance under rare earthquake based on seismic design specifications and high-rise building concrete structures technical regulations relevant requirements.And provided the basis for similar practical engineering. The paper research work and results as follows:(1) Further study on the roof structure selection and optimization. Propose three common roof forms for the design of project:cross beam roof, truss roof and cylindrical shell roof. Using modal response spectrum method and using SATWE and MIDAS/GEN for modeling analysis, which compares the force performance of cross beam when orthogonal or bias ply. And studied the impact of large space layer pillared force of grid and the different span ratio of shell, and compared the economic indicators of different scenarios. The results show that the program using truss roof structure are more economical and reasonable.(2)Top layer with large-span structure, the damage increased due to vertical stiffness suddenly decrease in the higher modes and under the influence of whiplash effect and very unfavorable for aseismic. By choosing three seismic waves in this paper, it conducted elastic dynamic analysis supplementary calculations under frequent earthquake for different scenarios. The results shows that the resulting elastic time history analysis of structural response was less than response spectrum method results and the response spectrum calculations are more conservative. In addition, the top layer acceleration values magnification is relatively large and verified whiplash effect of such structures.(3) Considering the impact of higher modes and study pushover analysis of structure under rare earthquake and evaluation the structure seismic performance using multi-modal load. The results show that the performance points of structure emerged, the plastic hinge first appeared in the end of the beam while the columns and walls plastic hinge did not appeared and meeting the "strong column and weak beam" design principles. In the stiffness mutation position there were no obviously weak layer and plastic hinge development and destruction process were reasonable.