PERFORMANCE OF REPAIRED REINFORCED CONCRETE T-BEAMS

Abstract

This research study deals with the performance of reinforced concrete T-beams strengthened in shear under static and cyclic loads. A total of six T-beams was tested simply supported under a point load at the midspan. Except for the control beam, all beams were strengthened with the provision of additional stirrups and galvanised wire mesh in a thickened section cast using non-shrink grout. Three of the beams were strengthened using prefabricated stirrup cages and two types of anchorage system were utilised, through the web and through the flange. The other two beams were strengthened using the conventional way of attaching additional stirrups, inserting U-shaped links through pre-drilled holes in the flange and bending them to form closed links. The original and additional stirrup spacings for all the beams were maintained at 200 mm. To simulate actual loading conditions of reinforced concrete structures during their service life, the strengthened beams were subjected to cyclic loading prior to static loading to failure. Their performances were compared with respect to cracking behaviour, concrete and steel strains, midspan deflections, stiffness deterioration, ultimate strengths, and mode of failure. The effects of static and cyclic loading are also discussed. The semi-empirical equation proposed by Sabarathinam[23] was used to estimate the static shear strengths of the strengthened beams and it was found to give better predictions compared to predictions in accordance to codes of practices, BS 8110[35] and ACI 318[34].