Temporary Repairs In order to accommodate the time required for the funding, design and construction of a new garage to replace the current facility, the existing garage required some repairs so that it could remain in service. Therefore, the following measures were recommended in order to extend the life of the structure another ten years: 1) Remove approximately two inches of existing concrete at the underside soffit of all level-three cast-in-place, post-tensioned girders and precast, prestressed girders, and approximately 25% of the level-two precast, prestressed girders, for the full length of the beams in order to inspect the condition of the tendons and mild reinforcing. If no further repairs were required, replace the removed concrete with high-strength grout, otherwise repair the girder reinforcing as required (Figure 1). 2) Install a passive galvanic protection system, such as Galvanode ASZ+ manufactured by Vector Corrosion Technologies, by coating the sides and bottoms of all cast-in-place, post-tensioned and precast, prestressed girders with the repair product (Figure 2). A detailed discussion of the protection mechanism and installation of this type of product is available in the manufacturer’s literature. The passive galvanic system should limit the amount of future deterioration of the girders for an additional five years based on the recommendations of the manufacturer. 3) Due to the lengthy anticipated funding, design and construction timeline for a new garage -- beyond the extended five-year service life provided by the passive galvanic system -- it was also recommended the concrete girders be shored (Figure 3). The purpose of the proposed shoring posts, located at third points of all of the girders in the garage, was to reduce the stresses imposed on the beams due to transient loads, such as those from cars and snow. However, installation of the shoring would not reduce the existing residual dead load stresses, because it was impractical to jack the beams up at each shoring location in order to relieve the existing dead load.
Posted on: Mon, 12 Jan 2015 10:20:00 +0000
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