On the Creep and the Relaxation of Spiral Ropes

Abstract

Spiral ropes are widely used as standing ropes in long bridges, suspension bridges or constructions with suspended ceilings. In these constructions, creep strain occurs inevitably. Also a relaxation of stress of PC strands ( a kind of spiral rope ) used in the prestressed concrete occurs. Therefore, to estimate the creep strain and the relaxation values of spiral ropes is one of the important problems in the design of bridges and prestressed concrete structures. The authors have carried out creep and relaxation tests of spiral ropes used as standing ropes and have calculated the creep strain and relaxation values by considering the creep strain of a single wire and by applying the analytical method, whose validity has been proven for the purpose of understanding the mechanical properties of ropes. Consequently, it has been made clear that the creep strain and the relaxation are influenced by the clearance between wire layers of the rope, and that they can be estimated by the analytical method presented in this paper.