A Study of Appropriate Methods to Repair Prestressed Concrete I-Girder Bridges : In the Event of a Cargo Ship Collision into a Bridge Pier Structure

Bridges are an important part of the transportation system. When the bridges are used, they might be damaged due to the deterioration with age or from the accident at any time such as a cargo ship collision into bridge pier structures. This research was the study by collecting the information for structural damage in bridge due to ship-collision accident and also providing the guidelines for inspection and repair method of the bridge structure. The dimension of bridge structure used in this study would refer to actual sizes used of the Thailand. There were two traffic lanes and span length of 30 meters. Deck slabs were supported by prestressed concrete I-girder, and all loads were transferred to crossbeam and then 5 piers, respectively. A structural damage caused by a ship collision was determined based on actual survey information. Most of the outside piers supporting the crossbar were damaged. The bridge structure before and after accident was analysed in 2D and 3D using SAP 2000 program. The methods for structural repair were divided into 4 groups depending on strengthening methods such as enlarged section, post-tension technique and pier replacement with new 1 or 2 bored piles. Based on the total score from 3 evaluation criteria including technique, price and durabity, it was showed that the post-tension technique or active strengthening could carry loads immediately and had better effectiveness than the strengthening using enlarged section method or passive strengthening.