Colorado School of Mines
connection details, finite element analysis, I-25, mechanically stabilized earth walls (MSEW), SCC, seismic design
The concrete abutments at the Mead Bridges on I-25 deteriorated in recent years due to unexpected freeway embankment movements. In many places the concrete had spalled off and exposed the steel reinforcement. The north abutments were especially affected by the embankment progressive movement towards the bridge. This movement forced the abutment against the steel girders, and progressed to the point where the abutment cover was crushed and the girders came in direct contact with the abutment reinforcement. It also resulted in buckling of the concrete deck, which was lifted off of the girders, resulting in a gap between the deck and the girders. To mitigate the problems described above, CDOT decided to ÛÏlockÛ the girders to the abutments with the use of SCC. The intent to use SCC was based on the need to have a flowable, yet stable concrete that could encapsulate the ends of the steel girders and the space in between them, without leaving voids at the interface of the new concrete and the existing deck slab, and without the need to vibrate the new concrete during placement. To achieve these goals, a high flowability concrete was designed with the intent of placing it through a number of holes at the deck within the encased area. One year after completion of the repair, inspections of the abutments were made in order to verify the performance of the repair after a full cycle of seasonal temperature changes. The inspection found that the concrete placed around the girders is performing as intended. No significant cracking or other indications of concrete failure were seen.