Shear strengthening of RC beams with prestressed NSM CFRP: Influencing factors and analytical model

• Published in: Composite structures 2024-08, Vol.342, p.118262, Article 118262
• Main Authors: Guo, Hengliang, Liao, HaoHan, Su, Miao, Zhang, Bai, Li, Shaofang, Peng, Hui
• Format: Article
• Language: English
• Subjects: Modified compression field theory; Near-surface-mounted; Prestressed carbon-fiber-reinforced polymer; Shear-strengthening; Web concrete cover separation
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2024.118262

This study proposes the application of prestressed near-surface-mounted (NSM) carbon-fiber-reinforced polymer (CFRP) technique in the field of the shear-strengthening of bridges for the first time. Fourteen reinforced concrete (RC) beams shear strengthened with prestressed NSM CFRP were tested under static load. The effect of the CFRP prestressing level, spacing, angle, and end-anchorage measures on the shear-strengthening behavior was evaluated. The experimental results demonstrate that the ultimate shear capacity of prestressed NSM CFRP shear-strengthened beams increased by 65–127% when compared to that of the reference beams, and the width of shear cracks was effectively suppressed. The failure mode of prestressed NSM CFRP shear-strengthened beams without end-anchorage measures was web concrete cover separation, which can be suppressed using a CFRP U-jacket and through-beam screw. Increasing the CFRP prestressing level and percentage enhanced the ultimate shear capacity and cracking resistance of the strengthened beams. However, an excessively high CFRP percentage and prestress level combination resulted in large shear crack angles and decreased the shear contribution of CFRP and concrete. Finally, an analytical model based on the modified compression field theory (MCFT) was proposed to predict the flexural-shear load response of strengthened beams, which was in agreement with the experimental results.