大型柔性摩天轮轮辐索预张力确定方法研究

Spoke Cable Pre-stress Determination of Large Scale Flexible Ferris Wheels

以北京朝天轮结构设计为背景,通过分析确定轮辐索预张力需考虑的因素,给出了确定大型柔性摩天轮结构轮辐索预张力的方法,包括预张力值域的确定方法及其调整方法,在值域范围内调整预张力需考虑的各种因素,及估算合理预张力的简便算法.指出轮辐索预张力值域上限由180度索是否满足轮辐索安全系数确定,值域下限由0度索是否松弛确定;减小轮缘自重或适当减小轮辐索的安全系数可增大值域范围,而增大轮辐索截面积可能引起调整预张力的恶性循环;轮辐索预张力的确定还需考虑轮缘平面内外的刚度及90度索的松弛;由于轮辐索预张力和轮缘自重的比值R可大致决定结构的受力特性,故大型柔性摩天轮结构可采用与北京朝天轮相近的R值初步预估轮辐索预张力值.

This paper provided a practical method to decide the reasonable spoke cable pre-stress for flexible Ferris wheels. By analyzing the factors influencing spoke cable pre-stress, this paper proposed a method to determine pre-stress value range and a method to adjust the value range, pointing out that the lower limit is determined by the slack of the 0 degree cable, and the upper limit is controlled by the safety factor of the spoke cable. The reduction of wheel weight and spoke cable safety factor can both expand val- ue range, but the increase of spoke cable section area may cause a vicious cycle in spoke cable pre-stress ad- justment. Other factors affecting spoke cable pre-stress, including wheel rigidity and cable sag, were also analyzed. Besides, since the mechanical property of flexible Ferris wheels can be generally decided by the ratio R of spoke cable pre-stress and wheel weight, flexible Ferris wheels of different scales can take simi- lar R value as Beijing Great Wheel to decide an approximate pre-stress value.