Mohamed Khalid, Abdalla Jamal A, Hawileh Rami A
Formerly Graduate Student, American University of Sharjah; Sharjah P. O. Box 26666, UAE.
Civil Engineering, American University of Sharjah, Sharjah P. O. Box 26666, UAE.
Materials (Basel). 2020 Sep 30;13(19):4350. doi: 10.3390/ma13194350.
Reinforced concrete (RC) beams strengthened in shear with carbon fiber reinforced polymer (CFRP) laminates as externally bonded reinforcement (EBR) usually fail due to debonding. This paper presents an experimental and analytical investigation on the use of groove-epoxy as an anchorage system for CFRP plates and sheets bonded on both sides of shear deficient RC beams. The aim of this study is to assess the effectiveness of using groove-epoxy in enhancing the shear capacity of RC beams. Nine rectangular RC beams were strengthened with CFRP plates and sheets with groove-epoxy anchorage systems of different groove widths and tested under four point bending. It is observed that the RC beams strengthened with the groove-epoxy anchorage system showed an increase in the shear-strength over the unstrengthened control beam up to 112 and 141% for plates and sheets, respectively. Also, the increase of shear-strength contribution of the groove-epoxy system to that of CFRP without grooves ranged between 30-190% for CFRP plates and between 40-100% for CFRP sheets. Generally, the contributions of groove-epoxy on shear-strength decreased with the increase of groove width. Moreover, shear strength prediction models, based on modifications of the ACI440.2R-17 shear model, were developed by incorporating groove factors as a modifier to the FRP shear-strength contribution. The developed models predicted the experimental shear-strength of the tested RC beams with a good level of accuracy, with an average mean absolute percent error (MAPE) = 3.31% and 6.68%, normalized mean square error (NMSE) = 0.072, 0.523, and coefficient of determination R = 0.964, 0.691, for plates and sheets, respectively.
采用碳纤维增强聚合物（CFRP）层压板作为外部粘结增强材料（EBR）进行抗剪加固的钢筋混凝土（RC）梁通常会因脱粘而失效。本文对采用凹槽 - 环氧树脂作为CFRP板和片材的锚固系统进行了试验和分析研究，这些CFRP板和片材粘结在抗剪能力不足的RC梁两侧。本研究的目的是评估使用凹槽 - 环氧树脂提高RC梁抗剪能力的有效性。九根矩形RC梁采用不同凹槽宽度的凹槽 - 环氧树脂锚固系统的CFRP板和片材进行加固，并在四点弯曲下进行测试。观察到，采用凹槽 - 环氧树脂锚固系统加固的RC梁，其抗剪强度相对于未加固的对照梁分别提高了112%（板）和141%（片材）。此外，凹槽 - 环氧树脂系统对抗剪强度的贡献相对于无凹槽的CFRP，对于CFRP板在30% - 190%之间，对于CFRP片材在40% - 100%之间。一般来说，凹槽 - 环氧树脂对抗剪强度的贡献随着凹槽宽度的增加而降低。此外，基于对ACI440.2R - 17抗剪模型的修改，通过纳入凹槽系数作为FRP抗剪强度贡献的修正因子，开发了抗剪强度预测模型。所开发的模型以良好的精度预测了测试RC梁的试验抗剪强度，对于板和片材，平均平均绝对百分比误差（MAPE）分别为3.31%和6.68%，归一化均方误差（NMSE）分别为0.072、0.523，决定系数R分别为0.964、0.691。
