持载和冻融循环对CFRP-高强混凝土界面的影响

Influence of Sustained Load and Freeze-Thaw Cycle on Bond Performance of High Strength Concrete Reinforced with CFRP

目的研究持续荷载与冻融循环共同作用下CFRP-高强混凝土的界面粘结性能.方法利用自制的持续加载装置对CFRP-高强混凝土试件施加不同等级的持续荷载并经过100次冻融循环后,通过双面剪切试验对界面的粘结性能进行研究.结果100次冻融循环作用后混凝土强度增长了1.4%.持载冻融作用下,CFRP片材的弹性模量最大差值没有超过4%.在12 kN的持续荷载和100次冻融循环共同作用下,破坏荷载与常温环境下的对比试件相比降低了1.6%,而极限端部滑移增加了1.5%,持载冻融条件并没有对破坏荷载和极限端部滑移产生显著影响,但在靠近加载端附近产生损伤区域,此区域内界面的剪切模量降低,界面破坏形态也发生了明显的变化.结论高强混凝土和CFRP片材有良好的抗冻性,在持载冻融环境下,CFRP加固高强混凝土结构具有较好的耐久性.

This paper presented an experimental investigation for the bond performance of high strength concrete reinforced with CFRP in the environment of sustained loading and freeze-thaw cycling. Using the sustained loading device designed by the authors, different level sustained loads were applied to the specimens and then subjected to 100 freeze-thaw cycles. Double side shear test was performed to investigate the bond performance of high strength concrete reinforced with CFRP. Results show that the compressive strength of concrete subjected to 100 freeze-thaw cycles increases by 1. 4%. The maximum difference of elastic modulus of CFRP is no more than 4% under sustained freeze-thaw cycle. By the combined actions of 12 kN sustained load and 100 freeze- thaw cycles, the failure load decreases by 1.6% ,but the ultimate global slip increases i. 5% , compared with contractive specimens in the room environment. There is no significant influence on the failure load and ultimate global slip under the combined actions of sustained load and freeze- thaw cycle. However, an damaged zone near the loading end occurs in which the shear modulus decrease and the failure mode changes. It indicates that the high strength concrete and CFRP sheet have good frost resistance. In the environment of freeze-thaw cycle and sustained load, the high strength concrete structure reinforced with CFRP has good durability.