External Plate Reinforcement for Concrete Beams

Strengthening concrete beams for shear forces by means of attaching steel plates to the external surfaces could provide a practical solution to the program of upgrading concrete bridges for carrying heavier loads. The experimental study carried out on three beams with 2, 4, and 6 mm plates attached by bolting to the vertical sides (web) of the beams resulted in considerable enhancement to the shear strength capacity. External plate attachment can also be designed to give simultaneous enhancement to flexural capacity. Although the beams failed in shear, as expected, the mode of failure was ductile, controlled by the yielding and local buckling of the external plates. The experimental study, although limited in terms of number of tests, showed that the method of construction could prove to be both practical and reliable for strengthening the existing in-situ concrete beams.