预应力CFRP布及预紧螺栓加固RC梁试验研究

Experimental analysis on RC beams strengthened with the pre-stressed carbon fiber sheets and pre-screwed bolts

为提高碳纤维布加固RC结构的效果及其可靠性,提出了预应力碳纤维布与预紧螺栓联合加固技术。结合在役RC梁的损伤特点及目前的RC梁加固方法,分别采用不同的碳纤维布加固技术对完整梁和破坏梁的抗弯性能进行了对比试验研究。针对目前碳纤维布张拉设备的缺陷,研发了便于现场应用的新型碳纤维布布张拉设备,分析了预应力大小对加固效果的影响。结果表明,预应力碳纤维布及预紧螺栓联合加固技术是一种更可靠的桥梁加固方法,不仅能够提高RC梁正截面的抗弯承载能力及正常使用阶段的截面刚度,而且螺栓预紧锚固碳纤维布能够很好地抑制其在混凝土表面的剥离,提高碳纤维布与混凝土表面之间粘结强度,对碳纤维布施加预应力能够充分发挥其高强性能,有效抑制混凝土裂缝开裂和开展。

To improve the strengthening effect and reliability of concrete structure strengthened with carbon fiber sheets, a new hybrid bonding pre-stressed carbon fiber sheets technique is developed. This technique combines the pre-stressed carbon fiber sheets with mechanical fastening of pre-screwed bolts. In accordance with the fracturing characteristics and the strengthening method of aging RC beam bridges, different carbon fiber sheets strengthening technology were applied on the intact and destructive RC beams. And a series of experiments were conducted to examine and assess the flexural performance of RC beams. Then, a new type of tensioning equipment was invented to meet the need of tensioning carbon fiber sheets in practical engineering. The experiment results show that the hybrid bonding pre-stressed carbon fiber sheets is a more reliable strengthening technique which can not only improve the flexural capacity and the section stiffness of RC beams during normal use stage, but atso can increase the cohesive force between carbon fiber sheets and concrete interface. It can make full use of the tensile strength of carbon fiber sheets and can restrain the opening and developing of the cracks.