Partially Strengthened Main Cable System for the Rehabilitation of an Old Suspension Bridge

Bridge rehabilitation projects for enhancing the safety and serviceability of old bridges are carried out widely around the world. Especially, suspension bridges are intensively maintained with high construction budgets. The damaged hanger rope, stiffening girder and main tower in suspension bridges can be repaired, strengthened or replaced. However, in the case of a main cable, the remedy until now only removes rust and applies surface repainting. Basically, the main cable consists of thousands of small wires, which is not replaceable. A damaged or disconnected wire also cannot be repaired or replaced. This paper suggests a new method for strengthening a main cable that is deteriorated by the aging effect. By small cables connecting a couple of cable bands on both sides from a pylon, the strength of the main cable can be increased and the possibility of slip of the cable bands are decreased. This suggestion is introduced by an example of an old suspension bridge that has been opened to traffic for forty years. The reinforcing level of the main cable should be decided by the extent of damage. Hence, the level of strengthening of the main cable can be easily controlled by only the amount of ancillary cables.