Structural Behaviour of Externally Bonded, Steel Plated RC Beams after Long-Term Exposure

The main aim of this paper is to evaluate the structural behaviour of externally bonded, steel plated reinforced concrete beams which were initially exposed to the natural elements for periods of 11 to 12 years and then subsequently tested to failure in the laboratory. Twenty-one beams were tested, of which eight were kept under sustained load and the rest left unloaded during the exposure period. No maintenance or cleansing of the beams was carried out during exposure. The main variables investigated included thickness ofthe adhesive layer, number of steel plates, and number and location of plate laps. The beams were extensively instrumented prior to load testing, and concrete strains, deflection, cracking and steel plate strains were continuously monitored during testing through to failure. The structural behaviour of the beams at the service and ultimate limit states and their failure modes are reported and analysed. Judged on the basis of stiffness and failure loads, the performance of the beams after 11-12 years' exposure was very satisfactory. Many beams retained their structural integrity and ductility, and all the beams failed at loads of 1 % to 29% higher than those of the equivalent control plated beams.

Professor R.N. Swamy, Professor B. Hobbs and M. Roberts