This paper studied the effect of incorporation of carbon nanotubes (CNTs) in carbon fiber reinforced polymer (CFRP) on strengthening of reinforced concrete (RC) beams. The RC beams were prepared, strengthened in flexure by externally bonded CFRP or CNTs-modified CFRP sheets, and tested under four-point loading. The experimental results showed the ability of the CNTs to delay the initiation of the cracks and to enhance the flexural capacity of the beams strengthened with CFRP. A nonlinear finite element (FE) model was built, validated, and used to study the effect of various parameters on the strengthening efficiency of CNTs-modified CFRP. The studied parameters included concrete strength, flexural reinforcement ratio, and CFRP sheet configuration. The numerical results showed that utilization of CNTs in CFRP production improved the flexural capacity of the strengthened beams for U-shape and underside-strip configurations. The enhancement was more pronounced in the case of U-shape than in the case of use of sheet strip covers on the underside of the beam. In case of using underside-strip, the longer or the wider the sheet, the higher was the flexural capacity of the beams. The flexural enhancement of RC beams by strengthening with CNTs-modified CFRP decreased with increasing the rebar diameter and was not affected by concrete strength.

本文研究了在碳纤维增强聚合物 (CFRP) 中掺入碳纳米管 (CNTs) 对钢筋混凝土 (RC) 梁的加固效果。制备 RC 梁，通过外部粘合的 CFRP 或 CNTs 改性 CFRP 片材进行抗弯加固，并在四点加载下进行测试。实验结果表明，碳纳米管能够延缓裂缝的萌生，并提高用 CFRP 加固的梁的抗弯能力。建立并验证了非线性有限元 (FE) 模型，并用于研究各种参数对 CNTs 改性 CFRP 强化效率的影响。研究的参数包括混凝土强度、抗弯配筋率和 CFRP 板材配置。数值结果表明，在 CFRP 生产中使用 CNT 提高了 U 形和底边条配置的加强梁的抗弯能力。与在梁下侧使用板条盖的情况相比，U 形情况下的增强更为明显。在使用底边条的情况下，板材越长或越宽，梁的抗弯能力就越高。用 CNTs 改性的 CFRP 加固对 RC 梁的抗弯增强随着钢筋直径的增加而降低，并且不受混凝土强度的影响。板材越长或越宽，梁的抗弯能力就越高。用 CNTs 改性的 CFRP 加固对 RC 梁的抗弯增强随着钢筋直径的增加而降低，并且不受混凝土强度的影响。板材越长或越宽，梁的抗弯能力就越高。用 CNTs 改性的 CFRP 加固对 RC 梁的抗弯增强随着钢筋直径的增加而降低，并且不受混凝土强度的影响。