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在预应力混凝土塔筒的挠度和裂缝宽度计算中 ,截面的刚度是必不可少的基本资料。虽然我国《混凝土结构设计规范》给出了截面刚度的计算公式 ,但由于其形式复杂 ,原高耸结构设计规范没有采用 ,而是给出了一个适用于普通钢筋混凝土塔筒的刚度降低系数。为了适应预应力高耸结构变形和裂缝宽度计算的需要 ,本文在混凝土结构设计规范公式的基础上 ,提出了利用预应力度来求解截面刚度降低系数的简单方法。由混凝土结构设计规范给出的公式可以看出 ,刚度降低系数与预应力、外荷载及截面配筋率等很多因素有关。而预应力度是一个把外荷载和预应力及截面配筋率联系起来的量 ,因此本文利用了预应力度的这个特点 ,通过选取承受不同荷载的各种塔筒截面 ,计算其在不同预应力度配筋情况下的刚度降低系数值。根据计算的结果 ,分析了预应力塔筒截面刚度降低系数随预应力度的变化趋势 ,并拟合出刚度降低系数与预应力度之间的关系曲线和计算公式。为预应力高耸结构的设计计算提供了参考。
In the calculation of deflection and crack width of prestressed concrete tower, the stiffness of cross section is the essential data. Although the formula of concrete structure design gives the calculation formula of section stiffness, because of its complicated form, the original design code of high-rise structure does not adopt, but gives a stiffness reduction coefficient suitable for ordinary reinforced concrete tower. In order to meet the need of prestressed high-rise structure deformation and crack width calculation, this paper proposes a simple method of using prestress force to solve the stiffness reduction of cross-section based on the formula of concrete structure design. According to the formula given by the design code of concrete structure, it can be seen that the coefficient of stiffness reduction is related to many factors such as prestress, external load and section reinforcement ratio. However, the prestressing degree is an amount that connects the external load with the prestress and the ratio of the section reinforcement. Therefore, this paper makes use of the characteristic of the prestressing degree. By selecting various tower sections with different loads, Stiffness reduction factor value under stress reinforcement. According to the calculation results, the trend of the stiffness reduction coefficient of the prestressed tower section with the prestressing force is analyzed, and the curve and formula of the stiffness reduction coefficient and the prestressing force are fitted. It provides a reference for the design and calculation of prestressed tall building.