The Analysis On Mechanical Behavior And Design Advice Of Reinforced Concrete Tube-in-tube Structure Of Large Length-width Ratio

In the recent years,with the continuous improvement of urbanization level and rapid development of community economy of our country,especially land resource is decreasing rapidly,the height of architecture are increasing and high-rise buildings of irregular shapes emerge continuously.All these bring great challenges to structure designers.This article does some research and analysis on the design problem in a high-rise building program of tube-in-tube structure.In this article,the characteristics of high-rise buildings、tube structure、tube-in-tube structure and the research status at home and abroad are reviewed and a general situation of this high-rise building of tube-in-tube structure is given.After that the influence of shear-lag effect and torsion effect with different length-width ratio.Then the design difficulty is researched and analyzed,that the displacement angle of Y-direction can not meet the design requirements.Afterwords different solutions are proposed and calculated with Midas Gen software,the results of calculations are compared and the the conclusions are summarized in the end.Through the analysis,the conclusions are as follows:(1)After the calculations under small earthquake、seismic earthquake andlarge earthquake,time history analysis of the elastic dynamic and pushover analysis,all the parameters meet the codes and the structure design meets the seismic performance objectives.(2)After the calculation of five models of different length-width ratio,the influence of length-width ratio to shear-lag effect is analyzed.The result is that with the enlargement of length-width ratio,the shear-lag effect is magnified,but the range is not large.When ascertaining length-width ratio,the shear-lag effect could be out of consideration,but the effect to lateral stiffness should be paid attention to.(3)After calculation of five models of different length-width ratio,the torsion effect is enlarged with the magnification of length-width ratio,the displacement ratio is enlarging more.To decrease torsion effect,it is inadvisable when length-width ratio is bigger than 2 and it should not be bigger than 3,and measures should be taken when length-width ratio is large to decrease torsion effect.(4)Increasing the cross-sectional area of columns and the height of beams both could enhance resist-lateral rigidity of structure,but when enlarging one of them which makes the stiffness difference between columns and beams is too huge,the effect of enhancing resist-lateral rigidity is not perfect.(5)Increasing the usage of section steel also could enhance resist-lateral rigidity and decrease the displacement angle,but the manufacturing cost is increasing rapidly,which makes the cost performance poor.(6)Setting the outrigger trusses and strengthened story could enhance resist-lateral rigidity effectively,but performing this out of the story of maximum of displacement angle works finitely.(7)Setting buckling-restrained braces of large amount could effectively decrease the displacement angle,but it could increased the cost.At the same time,the using functions of buildings are restrained.