多高层建筑结构考虑施工过程的内力分析

Analysis of the Internal Force in Tall Building Considerd by Construction Process

多高层建筑的结构自重是逐层施加的,施工过程中结构自重只作用于已施工完成的结构上,对上层未建结构内力无影响,而常规设计方法是以整体结构为计算模型进行设计计算,因此设计的计算模型与实际施工情况不吻合,结构内力的设计值将与实际值出现偏离.根据结构力学原理以多高层框架为研究对象建立了采用常规设计法计算所得的梁、柱弯矩偏离实际值大小的相对差公式.进而分析了结构的层数、结构的跨数、梁柱线刚度比、结构的自重荷载等各种因素对框架梁、柱弯矩偏离实际值的影响.当采用常规设计法以整体结构为计算模型时,由本文提供的梁柱弯矩相对差曲线对结构各构件控制截面处内力进行修正,可以满足设计的要求.

Construction process should be considered in structural analysis because the self-weight only affects the finished part of the structure and does not act on the unfinished part. However tall buildings are generally designed on the basis of the whole structure under total loads so that the internal forces are different from the real value. In this paper, the formula for estimating the relative deviation of internal forces obtained by the normal design and by considering construction process is provided applying the principle of structural mechanics. Some factors such as floors、spans、sites、loads and the stiffness ratio of column to beam having influence upon structural performance are discussed. Through calculating reinforced concrete frames, the bending moments obtained by considering construction process are compared to that of design model. Then the relationship between the relative moment deviation and the stiffness ratio of column to beam is drawn. It is suggested that calculated model should accord with the construction process in the design of tall buildings. Lastly, the simple method is put forward to modify the internal forces of design model.