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SP-165 The ACI Technical Session "Repair and Strengthening with Adhesive Bonded Plates" was held in Washington, D C on March 15-16, 1992. The papers presented at the technical session and the additional papers included in this special publication provide the first comprehensive publication of information on this subject in the United States. The papers cover research, design, construction methods, and case histories. The research described includes not only theoretical analysis and short-term experimental programs but also test programs that involve long-term outdoor exposure. research in the use of fiber reinforced plastic plates instead of the more commonly used steel plates is also described. The design papers illustrate practical engineering approaches and include details of anchoring plates, effect of plate dimensions, adhesive performance, and temperature limitations. Construction methods described include preparation of the plates, application of adhesive, and installation of the plates. The case histories provide a broad and historical view of the use of adhesive bonded plates to strengthen buildings and civil engineering structures.

The plate bonding technique has been known and established in Europe for more than 20 years. Up to the present time, however, it has only been used in some specific applications. This is mainly due to the lack of an integral system approach. The increasing demand for strengthening, repair, and rehabilitation measures, especially in the field of the maintenance of structures, and the seismic upgrading or the change in use of structures ask for structural reliability and cost effectiveness. Both can be met with a new system approach for the plate bonding technique focusing on the requirements of engineering based design fundamentals; increase in ductility and strength, provided with permanent pressure applied to the steel plate; safe and easy handling on jobsite with adequate application system; overall quality control and assurance; integration of other plate/strip materials; and extension of the system to other subground material (masonry, wood, steel). A new system for the end anchorage of the bonded steel plates has led to a pronounced increase in ductility of the overall structural system so that the stringent requirements for structural elements used in engineering design can be met in full. A new design procedure is in development, based on extensive laboratory tests and preliminary field tests, as well as on finite element calculations. The new design procedure is fully in length with current developments in reinforced concrete design.

The use of steel plates bonded with epoxy adhesives to reinforced concrete structures is a technique more than 25 years old. In this paper, the applications of using this technique for construction of new structural members and strengthening of existing members are reviewed. For the strengthening of reinforced concrete beams and columns, preloading prior to bonding of steel plates is studied to simulate the in situ strengthening process. For upgrading of columns, the transfer of stresses, lateral confinement of the concrete section, and failure modes are described. From the experiments carried out, it is concluded that strengthening with epoxy- bonded steel plates alone will not increase the ultimate strength of the column, though the stiffness in enhanced marginally. However, additional inclusion of lateral confinement plates improves its strength. In particular, the post-failure mode and post-failure strength may lead to highly potential applications. Test results of scale models are discussed and tentative design criteria recommended.

The steel plate bonding technique appears to be a reliable strengthening and repair method to rehabilitate existing reinforced concrete structures. An overview of concrete deterioration is presented, in which the plate bonding technique as a repair and strengthening method for concrete structures is included. By presenting some repair projects conducted under the supervision of the author, the technique of gluing steel to concrete in different damage situations is illustrated. The possibilities, advantages, limits, and practical implementation aspects of the technique are discussed.

Although strengthening by bonded steel plates, where adhesive is used to bond the steel plates to the structural members, has been established for more than two decades, it was not until recently that this strengthening technique has been used in Singapore. A number of reinforced concrete structures have been successfully strengthened using this technique over the last three years. This paper describes this strengthening technique with particular reference to the material selection and design considerations, as well as the strengthening and construction methodologies. A case study on one of the structures strengthened is also presented. The structural members strengthened include bonding of steel plates to beams to increase flexural as well as shear capacities and encasing columns to prevent buckling and increased load carrying capacity.