Exploring GFRP bars as reinforcement for rectangular and L-shaped beams subjected to significant torsion: An experimental study

• Published in: Engineering structures 2014-02, Vol.59, p.776-786
• Main Authors: Deifalla, A., Hamed, M., Saleh, Amin, Ali, Tarek
• Format: Article
• Language: English
• Subjects: Applied sciences; Bars; Beams (structural); Bent GFRP stirrups and L-shaped beams; Bonded GFRP stirrups; Building structure; Buildings. Public works; Construction (buildings and works); Exact sciences and technology; GFRP bars; Glass fiber reinforced plastics; Materials; Plastics; Reinforced concrete structure; Reinforcement; Shear strength; Stirrups; Structural steels; Torsion
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2013.11.027

•A new adhesively bonded GFRP stirrup is presented and implemented.•Bonded GFRP stirrups were found to be more effective compared with bent stirrups either steel or GFRP.•Fourteen beams were found in the literature and five beams were constructed and tested under significant torsion.•The increase in the GFRP transversal percentage increased the ultimate strength, the toughness and the ductility. Steel corrosion related problems have been a heavy burden on countries economically and socially for many decades. Therefore, the inevitable quest to find an alternative for steel reinforcements is long overdue. On the other hand, fiber reinforced polymer (FRP) bars have non-corrosive nature and could be the solution for this problem. In this study, the objective is exploring the usage of glass fiber polymer (GFRP) bars as torsion reinforcement for L-shaped beams. New adhesively bonded GFRP stirrups are presented and implemented. Five beams were constructed and tested under significant torsion. The bonded GFRP stirrups were more effective as transversal reinforcement compared with the bent steel stirrups and the bent GFRP stirrups. It improved the ultimate torsional strength and increased the corresponding unit angle of twist and the maximum stirrup strain as well as the major concrete crack width. In addition, the increase in the GFRP transversal reinforcement percentage improved the ultimate torsional strength, the toughness, and the deformability. Moreover, the usage of a stirrup strain value of 0.4% resulted in overly conservative predictions for the ultimate torsional resistance; however, it provided adequate torsional deformability index and toughness.