Influence of GFRP Vertical Stirrups Using NSM Technique on Shear Behavior of Reinforced Concrete Beams with Recycled Coarse Aggregate

Abstract

Shear strengthening with GFRP rods is the focus of this paper on concrete beams that contain aggregate replacement ratios of thermstone and bonza (pumice materials), obtained from the rubble of demolished buildings. A total of nine beams (2400×160×300mm dimensions) were loaded under a four-point bending load test. The parameters examined in this research were the replacement ratio of lightweight coarse aggregate (20% and 30% volumetric ratio), type of lightweight aggregate replaced by (thermstone or bonza) and strengthened in shear by GFRP rods using NSM technique. The characterization of the tested beams includes ultimate load, failure mode, load-deflection curve, load strain curves of stirrups, bottom longitudinal rebars, GFRP rods at the shear zone of concrete. The results showed that the use of GFRP rods to strengthen concrete beams was effective. As the failure mode was transformed from a shear failure in the reference beam that was cast using normal concrete to a concrete compression failure in the beams which was occurred when using suitable and sufficient amount of strengthening by GFRP rods for selected used lightweight aggregate replacement ratios.