<p>RESEARCH NEEDS FOR Structures TAG</p><p>EFFECTIVE/UPDATED 8/15/2017</p><p>ISSUE: Longitudinal Keyways on Precast Concrete Deck Beam (PPCDB) Bridges</p><p>SUMMARY OF PROBLEM: PPCDB bridges have been used on the local agency roadway network for many years with great success. Depending on the location and the preference of the facility owner, some deck beam bridges receive an overlay as part of initial construction and some do not. With age, some bare surfaced deck beam bridges receive an overlay to improve water resistance and to improve ride quality. On very low-volume roadways, this initial or follow-up overlay is many times a simple oil and chip, or sealcoat, surface which is generally very thin (< 1/2-inch). </p><p>An integral part of deck beam bridge design is the keyway between each deck beam. The deck beams are generally tensioned together and the keyways are grouted to provide a solid bridge deck, which should act and respond uniformly to applied loadings. With age and distress, some of the keyway joints may deteriorate slightly, allowing for slight rotational movements and independent beam movements with applied loadings. </p><p>The application of a thin seal coat overlay to a deck beam bridge that is experiencing these slight independent movements will naturally produce a longitudinal crack on the surface along the length of the bridge over the keyway. The bridge is still functioning properly and has many years of life left.</p><p>The presence of the crack in the overlay on the surface has resulted in some bridge evaluators automatically reducing the condition rating for the bridge superstructure. The problem is that the rating reduction may be unfounded. Currently there is not a good evaluation tool for the condition of keyways on deck beam bridges, especially on those bridges that have been overlaid.</p><p>DESIRED RESULTS/OUTCOME: The desired outcome of this research effort would be an evaluation method and scoring criteria for the condition of in-service keyways on deck beam bridges (both with and without overlays). </p>