Experimental research on bending performance of structural cable

• Quasi-static bending tests on semi-parallel wire cables, stranded ropes and steel spiral strands (Galfan) were performed.
• Different end conditions and the present and magnitude of pretension were considered.
• Bending behavior of cable was analogous to an elastic–plastic metallic beam.
• Welded end can add integrity to the cable but this strengthening effect is weak.
• Pretension can increase the cable flexural stiffness.

Studies on bending properties of cables have long history but those researches are mainly around electrical conductors with very limit experimental discussions on structural cables. One approach on dynamic problems are through understanding changes in bending stiffness and utilized the varying bending rigidity into beam theory or beam finite element analysis. Therefore, a serial of quasi-static bending tests on semi-parallel wire cables, stranded ropes and steel spiral strands (Galfan) were performed to understand the cable bending response, with considering different factors like end conditions and the present and magnitude of pretension. The effective flexural stiffness of those structural cables were then determined and compared. Test results indicated that the unstressed cables under bending had an elastic–plastic like force–displacement response, which was analogous to an elastic–plastic metallic beam. Galfan strands showed better wire bounding behavior and cooperative bending due to different winding method. Welded end measurements can add integrity to the cable but this strengthening effect is weak and limited. Flexural response of the cable under a constant tension force was more like a linear relation with sag deflection. Pretension can increase the cable flexural stiffness, and this strengthening effect increased with the pretension level but decrease with the cable dimension. A simplified evaluation method of effective flexural stiffness was also proposed.