用约束力计算Levy型索穹顶初始预应力的方法

提出了一种通过约束力来计算Levy型（葵花型）索穹顶结构初始预应力的方法.选定便于分析的多余约束,用约束力代替约束,根据力的平衡,首先推导了轴对称Levy型索穹顶相邻节点间脊索与斜索共同传递的竖向力及水平力计算公式;然后给出了由竖向力和水平力计算杆件初始预应力的计算公式.初始预应力计算分为两部分：一部分对应约束力为零并承受竖向荷载;一部分对应约束力为P的自平衡预应力.自平衡预应力随约束力P成线性变化,可以通过增加约束力P对应的自平衡预应力水平提高整个索穹顶结构的初始预应力水平,达到满足各种荷载工况下的受力要求.最后,通过算例描述了方法的计算过程并验证了方法的正确性.此方法计算简单,便于结构计算和调整初始预应力值.

A method to calculate the initial prestress of Levy domes via constraint forces

A method using the constraint force to calculate the initial prestress of Levy domes is proposed in the paper.The redundant constraint,which is replaced by constraint force,is selected in order to calculate easily.The vertical force and horizontal forces transferred between adjacent nodes are calculated for the axial symmetry Levy domes based on the equilibrium of forces.The equations for the initial prestress of the ridge cables,down cables,hoop cables and struts are derived.The initial prestr~ can be divided into two parts,the first part corresponds to the zero constraint force and supports the vertical loads,the second part corresponds to the self-equilibrating initial prestress of the constraint force P.The self-equilibrating initial prestress is linearly changed with P.The initial prestress of the cable dome can be increased by increasing the constraint force P so as to satisfy different working conditions.An example is introduced to validate the present method in the section of numerical results.