钢骨混凝土框架-核心筒超高层混合结构竖向变形研究

钢骨混凝土框架-核心筒超高层混合结构竖向变形对结构的长期安全稳定影响显著。基于混凝土弹性、徐变和收缩变形的理论分析,推导了超高层建筑考虑结构施工过程的徐变计算式,依此建立了考虑超高层混合结构体系分级循环施加变荷载的竖向变形计算方法,并分析了施工过程对内外结构竖向变形差异的影响,最后,以深圳平安金融中心为工程背景,研究了超高层混合结构竖向变形规律和内筒与外框架的变形差异。结果表明:所提方法对超高层混合结构竖向变形的预测结果与工程实际测量结果误差较小,可反映超高层建筑的长期竖向变形及变形差的发展规律;超高层建筑竖向变形呈中部大、两端小的鱼腹形,结构施工期间,竖向变形最大值发生在中部位置,并随着服役期的延长,竖向变形最大值所在楼层逐渐上移;在施工期间,弹性压缩变形最大,徐变次之,收缩最小,而竣工后,徐变和收缩占总变形的比例不断增加,深圳平安金融中心竣工50a后的徐变收缩变形将达到弹性压缩变形的2～3倍;内筒剪力墙竖向变形比外框架柱大,且单层结构施工周期越短,内外结构长期变形差越大,核心筒超前外框架施工层数越多,变形差越大。

Vertical deformation of super high-rise steel reinforcedconcrete frame-core hybrid structures

The vertical deformation of super-high-rise steel reinforced concrete frame-core hybrid structures has a significant effect on the long-term safety and stability of the structure. Based on the theoretical analysis of elasticity, creep and shrinkage deformation of concrete, a method for predicting the creep effect of super high-rise buildings with the consideration of the construction process was deduced, and a vertical deformation calculation method of super high-rise hybrid structures was established which considered of the variable load applied by grade cycle. The influence of the construction process on the difference of the vertical deformation of the inner and outer structures was also analyzed. Considering Shenzhen Ping’an Financial Center as the engineering background, the vertical deformation law and deformation difference of the super high-rise hybrid structures were studied. The results show that the prediction of the vertical deformation of the super high-rise hybrid structure agrees well with the actual results, and hence the proposed method can well reflect the long-term vertical deformation and the development of the deformation difference of super high-rise buildings. The vertical deformation follows a fish belly mode with larger deformation in the middle part and smaller deformation at the perimeter. During the construction stage, the maximum vertical deformation occurs in the middle position, and with the increase of the number of years in service, upper floors start to show the maximum vertical deformation. In addition, the elastic compression deformation is the largest, the creep is the second largest, and the shrinkage is the smallest. After the structure is put into use, the proportion of creep and contraction in the total deformation keeps increasing. The creep and shrinkage deformation of Shenzhen Ping’an Financial Center after 50 years for use would have reached 2-3 times of the elastic compression. The vertical deformation of the inner core shear wall is larger than that of the outer frame column, and the shorter the construction period of the single-story structure, the greater the long-term deformation difference of the inner and outer structure, and the more number of the outer frame construction floors ahead of the core tube, the greater the deformation difference.