Shear Repair of Reinforced Concrete Beams Using Post-Tensioning

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Title: Shear Repair of Reinforced Concrete Beams Using Post-Tensioning

Author(s): A. R. Khaloo

Publication: Special Publication

Volume: 193

Issue:

Appears on pages(s): 519-550

Keywords: beam; concrete; deflection; ductility; flexural strength; post-tensioning; repair; shear strength

Date: 8/1/2000

Abstract:
In this paper, shear strengthening of RC beams by confining shear critical region is experimentally and theoretically investigated. Confinement is implemented using vertical post-compression force in the shear critical region with steel plate, bolts and angles. The loading tests include (1) loading beams to first major shear crack, then shear strengthening, and reloading to complete failure, (2) strengthening beams from beginning and loading to complete failure, and (3) loading unrepaired beam to complete failure. Influences of concrete strength, shear span length, longitudinal tensile reinforcement, level of post-tensioning, presence of shear reinforcement, use of continuous plates, and presence of shear crack are studied by testing twenty-four RC beams. Test results show that in the presence of post-compression stress, as low as 0.04f'c for strengthening, shear strength increases significantly and the mode of failure of the beams changes from brittle shear to ductile bending. Also, for this level of post-compression, influence of all other parameters is limited, while a ductile failure is dominant. Calculations based on Mohr’s theory also indicate that this method of strengthening is very effective, and provides ductile flexural behavior in beams with inadequate shear strength.