Structural Rehabilitation on Continuous Post-Tensioned Prestressed Concrete Box-Girder Bridge Exposed to Explosion: A Case Study

This paper focuses on a case study of a fourspan continuous prestressed concrete box-girder bridge that developed extensive damages to the deck and webs in two successive spans due to an explosion by a trailer charged with high explosive materials. The eight cell box-girder bridge is connecting Baghdad city with the other southern provinces of Iraq. The bridge is 166 m long, the deck and soffit slab widths are 20.5 m and 16.3 m, respectively, and the overall cross-sectional depth is 1.30 m. The importance of this structure from economic and traffic points of view has made it impossible to think of the total replacement. Accordingly, the possibility of the replacement of the four spans was ruled out due to the tedious nature of the process, the time and cost. The main two goals of the study were how to keep the prestressing effect and how to compensate the continuity in the nondamaged spans. To achieve these goals, mechanism for restraining was implemented directly at each cross-sectional web of a span at a pier location. Also, a strengthening of the two non-damaged spans of the box-girder bridge was performed by installing a series of steel plate strips at the top concrete fibers of the deck slab and bottom concrete fibers of the soffit slab. This approach improved the stress distribution in the deck and maintained the original load resistance mechanism provided by the prestressing arrangement in the box-girder.