冻融循环下预应力CFRP板加固钢筋混凝土梁的耐久性研究

预应力CFRP加固混凝土结构技术由于具有显著优势,越来越多地被应用在桥梁加固中,本文针对冻融循环作用下预应力CFRP板加固钢筋混凝土梁的耐久性能进行了实验研究。通过12片加固梁试件的实验研究了不同次数冻融循环作用下预应力CFRP板加固梁的破坏形态和承载性能,分析了混凝土强度等级、冻融循环次数、CFRP初始应力水平等因素对加固梁耐久性能的影响。实验结果表明:经历冻融循环后试件的开裂荷载和极限承载能力都有了不同程度的下降,冻融侵蚀对CFRP加固混凝土结构产生了明显的不利影响;随着冻融循环次数的增加,加固试件的破坏模式逐渐由混凝土保护层剥离转变为界面剥离的破坏形态;冻融循环作用对预应力加固试件的整体不利影响要大于非预应力试件;混凝土强度为C60的预应力CFRP加固试件在冻融侵蚀作用下的退化要较强度为C30的加固试件显著。

Durability Study of Reinforced Concrete Beam Strengthened with Prestressed CFRP Plate Under Freeze-thaw Cycling

Reinforced concrete structure strengthening technique by using prestressed CFRP laminates is applied more and more extensively in bridge strengthening due to its significant advantages. A total of 12 reinforced concrete beams were manufactured first, a part of which were strengthened with prestressed CFRP plate and the remains with non-prestressed CFRP plate, then experimental study of specimen's durability under freeze-thaw cycling was conducted. The failure mode and load-carrying capacity of the beams subjected to different freeze-thaw cycling times were investigated, and the influences of concrete strength, CFRP initial stress level and the freeze-thaw cycling number on the load-carrying behavior of the strengthened specimens were analyzed. Experimental results show that the cracking load and ultimate load of specimen decrease after freeze-thaw cycling, which indicates that freeze-thaw cycling weakens the load-carrying capacity of strengthened beams. With the increase of freeze-thaw cycling number, the failure mode of specimen transforms from peeling off the protective layer of concrete to debonding of interface between CFRP plate and concrete. The negative effect of freeze-thaw cycling on the beams strengthened with prestressed CFRP seems more significant than that of the beams strengthened with non-prestressed plate. The degradation of specimens with concrete strength of C60 under freeze-thaw cycling is more significant than that of specimens with concrete strength C30.