Static Analysis of a Suspension Bridge with Modified Hangers and Eliminating Slackness

Two kinds of hangers are used in suspension bridges: vertical and inclined hangers. Inclined hangers provide a damping system in the bridge structures to reduce vibration produced by lateral loads, whereas this kind of damping is not available for vertical hangers. Some of inclined hangers become slack because of their arrangement in bridges and some others are overstressed under external loads. In this paper a case study of a suspension bridge with inclined hangers has been investigated. Special attention has been made to reduce internal forces and fatigue in inclined hangers, as well as to eliminate slackness problems in hangers. A horizontal cable, attached to existing hanger system, has been proposed by the authors. The attached horizontal cables transfer the tension forces from overstressed hangers to the adjacent slack hangers. A Finite Element program in FORTRAN language has been provided to analyze the bridge. The results of analysis of the bridge with this program show that the modified system has improved the behavior of the bridge.