The Chiani Suspension Bridge: A Complete Overhaul

The paper presents the rehabilitation works carried out on the Chiani suspension bridge in Algeria. The bridge, designed by the French engineer Arnodin at the beginning of the last century, has a main span of 105 m and a mixed cable supporting system with a stayed deck portion near the towers. The bridge was designed and built before the similar Sidi M'Cid one in Constantine, Algeria. The strengthening works carried out on this bridge by the same authors during the 1990s was reported in Structural Engineering International (4/2000). Following the successful experience of the Sidi M'Cid bridge, the authors have been asked to engineer a complete overhaul of the Chiani bridge, a beautiful structure completely abandoned and closed to traffic because of its severe state of degradation. The works included the complete substitution of the suspension system, the widening of the superstructure with new pedestrian sidewalks moved out of the parapet girders and a new concrete deck to allow for unrestricted vehicular traffic to transit on it. Works have been carried out without supports from below, with the deck weight transferred from one suspension system to the other while the bridge remained open to pedestrian, motorbikes and herds. An innovative suspension system with resin-encased strands has been used for main cables, stays and hangers in lieu of ropes and steel bars. New saddles, made of welded plates following a concept originally developed for the third generation suspension bridges, have been placed over the existing ones with the two systems working in parallel during the load transfer.