Analysis of Cables as Equivalent Two-Force Members

Abstract

In recent years, cable structures have become more widely used because of growing demand for long-span construction for aesthetic, economic, or other practical reasons. Aside from classical suspension bridges, examples of this type of structure are tall guyed towers, cable-stiffened bridges, and suspended roofs. The methods of analysis of suspension bridges have been extensively explored, and will not be discussed herein. Instead, this paper presents a simplified analysis of cable members ordinarily encountered in the other types of structures mentioned above, by treating them as equivalent two-force members. The nonlinear behavior of such cables is accounted for by the use of an equivalent modulus of elasticity as well as equivalent strains. Problems commonly associated with cables, such as stresses (and change of sags) caused by a change of temperature or superimposed loads, or resulting from relative displacement of supports, can be readily solved by this method. It should be noted that the proposed procedure is also applicable to the analysis of transmission lines.