Rehabilitation and Retrofit of Babolsar Concrete Pedestrian Settled Bridge

The Settled Concrete Bridge or the Second Bridge of Babolsar is considered the oldest pedestrian bridge in Babolsar city of Iran along Caspian Sea shoreline. This utility bridge is constructed on Babolrud River in 1949 to facilitate commuting along its eastern and western sides for residents and tourists. The parts of the bridge are reinforced concrete and consist of four concrete piers in the river and five spans with a hinge support of almost equal lengths and a width of 2 m and length of 101 m. The bed of Babolrud River bed is too loose and unreliable because of sedimentation of deposits resulting from erosion and general scouring in upstream and there are geotechnical problems such as low bearing capacity and high settlement probability. The non-uniform settlement of 580 mm to 1320 mm had occurred in three piers of the bridge’s middle spans due to the river flooding in 1964 and local scour around the shallow foundation under the piers. Because of excessive settlement and rotation of the piers, the decks are locally bent in the support locations. In order to rehabilitate and repair the aforementioned bridge, some studies have been carried out about the geotechnical situations, hydrological conditions, the strength of structural elements of the bridge, damages estimation and approaches to rehabilitate the bridge. According to the surveys, the best approaches selected and implemented for the rehabilitation and repair of the bridge include: raising the bridge deck in three settled piers by deck seated jacking method and the use of braced metal chassis as a new piers. Then rehabilitation was done in destructed seat using concrete high-strength fibres to prepare link between the deck and the pier. The results after three years of rehabilitation and utilization have proved the functionality of the applied system in the rehabilitation of Babolsar first pedestrian bridge.