FRP索与钢索的求解计算和极限跨度

随着跨度的增大,自重对单索的影响就越明显,FRP(纤维增强复合材料）索的自重小,在大跨度结构中应用具有优势。单索的理论计算是索结构进行设计的基础。单索在自重作用下的求解,按照不同的假设,有弹性的悬链线解答、悬链线解答和抛物线解答。针对工程应用,以索端张拉轴力为已知量,推导了3种解答方法的求解方程,得到了关于张拉轴力的一元方程,方便了工程应用。另外,分别对斜拉索和水平索的悬链线解和抛物线解的精度进行了分析和比较,建议了2种近似求解方法的使用范围。根据求解结果,对FRP索和钢索的极限跨度进行了分析；结果表明FRP索有利于实现更大的跨度。FRP索的极限跨度可达钢索的4.4倍。

Comparision of Theoritical Solutions and Ultimate Span-Length between FRP Cables and Steel Cables

As the self weight of cable affects mechanical behavior obviously with the inerease of span length.FRP (fiber reinforced polymer) cable that has the lighter weight than the conventional cables has advantage for long span structures.The analysis of single cable is the fundamental theory for the design of cable structures.Based on different considerations of gravity loads.the solutions of the single cable on gravity loads have three sets of solutions: parabola solution.catenary solution and elastic catenary solution.And the equations for the three sets of solutions are derived by taking the end tension force of cable as the control parameter.The comparison between FRP cables and steel cables is conducted by elastic catenary solution.and the results show that the lager span structure can be realized by FRP cables.The precision for the parabola solution and catenary solution is compared for stay cables and horizontal cables.and the proper ranges of both approximate methods are proposed.Based on the above methods.the ultimate span length of FRP cable and steel cable are analyzed.It is concluded that the ultimate span of FRP cable is 4.4 times larger than that of steel cable.