Effect of Confinement Techniques on Mechanical Behavior of Over- Reinforced HSC Beams

Abstract

Over-reinforced high strength concrete, HSC, sections are restricted in most design codes to avoid the brittle compression failure of concrete which occurs suddenly without warnings. Recently, there have been significant improvements in construction industry that needs to use over-reinforced sections in huge projects such as, high-rise buildings and bridges. Limited trials have been carried out to strengthen the over-reinforced section by using proper confinement in the compression zone. This confinement restrains the lateral expansion and failure of concrete in the compression zone. HSC provides high strength but lower ductility than normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. This study investigates experimentally the effect of installing different configurations of confinement techniques in the compression zone of over reinforcement high concrete beams. These configurations contain confined by square ties, wrapping fiber reinforced epoxy sheet, and fiber reinforced concrete in compression zone. Four groups of beams made of HSC were cast and tested under three-point loading, with emphasis placed on the mid span deflection. The first group served as a reference beam. Results of testing the four groups proved that the suggested techniques of confinement for HS reinforced concrete beams gave highest values for first crack and ultimate loading and maximum beam deflection. Moreover, the crack pattern and mode of failures were changed from sudden compression-shear failure for control beam to multiple tensions cracking for confinement beams