Flexural behaviour of reinforced concrete beams strengthened with a composite reinforcement layer: BFRP grid and ECC

• Published in: Construction & building materials 2016-07, Vol.115, p.424-437
• Main Authors: Zheng, Yu-Zhou, Wang, Wen-Wei, Brigham, John C.
• Format: Article
• Language: English
• Subjects: Analysis; Basalt fiber reinforced polymer (BFRP) grid; ECC; Flexural behaviour; Mechanical properties; RC beams; Reinforced concrete; Strengthening; Structure
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2016.04.038

•A new FRP-ECC strengthening system for RC beams was proposed in this paper.•Flexural behavior of RC beam was greatly improved after strengthened with CRL.•Good bonding behavior of CRL-to-concrete interface was observed in the test program.•An analytical model was proposed to predict mechanical responses of strengthened beam. In this paper, a new strengthening technique for reinforced concrete (RC) beams is proposed by combining Basalt fiber Reinforced Polymer (BFRP) grid and Engineered Cementitious Composites (ECC) as a composite reinforcement layer (CRL). Five RC beams externally bonded with the CRL at the soffit and one control RC beam were tested to investigate their flexural behaviour. The thickness of BFRP grids (i.e. 1mm, 3mm and 5mm) and the bonded length of CRL (i.e. 400mm, 450mm and 500mm) were selected as two main parameters in the test program, while the width and thickness of CRL were fixed approximately at 200mm and 30mm, respectively. The test results showed that there is no clear CRL debonding in the strengthened beams. The two final failure modes were concrete crushing or rupture of the BFRP grids, indicating that the proposed technique is effective in suppressing the debonding of externally bonded materials and fully utilizing the material strengths. An analytical model is also presented to predict the load-deflection responses of the strengthened beams, which was validated through comparisons with the test results.