Collapse of Twelve-Mile Creek Bridge
The collapse of a prestressed I-section occurred during the erection of a 3-span continuous prestressed concrete bridge. The bridge was to be constructed using prestressed I-sections consisting of segments over each pier, segments between the abutments and pier unit, and "drop-in" segments at mid-length of the structure. After erection, the segments were to be grouted and post-tensioned, forming a continuous bridge.
Following collapse of one of the segments, CTLGroup was retained to investigate the cause of collapse. The work was done within the scope of a field inspection, laboratory tests, review of drawings, review of design calculations, and independent structural analysis. Investigation determined that soon after one of the first two segments had been placed, one of the girders "exploded" at a location between a temporary end support and the first pier. The other girder that had been erected was not damaged and remained in place.
CTLGroup's investigation resulted in a determination of the cause of this collapse. Based on these findings, changes were made that allowed the bridge to be erected without further incident.