CFRP-混凝土界面的疲劳性能

Fatigue Behavior of CFRP-Concrete Interface

为探明碳纤维增强复合材料(CFRP)-混凝土界面的抗疲劳性能,以碳纤维薄板(CFL)与混凝土的粘结界面作研究对象,设计了改进的双剪疲劳试件,在循环荷载下对CFL-混凝土界面的疲劳性能进行了实验研究;给出了CFL-混凝土界面的相对滑移演化曲线(相对滑移-疲劳寿命实验曲线),分析了界面的应变及其粘结滑移规律.实验结果表明:在疲劳荷载作用下,CFL上的应变演化主要由加载初期快速传力阶段、界面稳定传力阶段、界面失稳传力阶段构成,其中界面稳定传力阶段约占其疲劳寿命的95%左右;试件相对滑移的演化也分为初期快速增长、稳定增长、失稳增长3个阶段.在稳定增长阶段,试件的相对滑移与疲劳寿命之间呈近似的线性关系.最后,提出了基于刚度系数的CFL-混凝土界面的疲劳损伤模型.利用该模型,可较方便地推定CFL-混凝土的界面在疲劳过程中的损伤演化规律.

In order to verify the fatigue resistance performance of the CFRP （Corbon Fiber Reinforced Plastic）- concrete interface, the bonded interface is taken as the research objective and the double-shear fatigue specimens are designed to test the fatigue performance of the CFL （ Carbon Fiber Laminate） -concrete interface under cyclic loading. Then, the relative slip evolution curves （the relative slip of the specimen-fatigue life experimental curves） of the CFL-concrete interface are presented, and its strain and bond-slip laws are analyzed. The experimental results show that （ 1 ） under the fatigue load, the strain evolution on the CFL consists mainly of three steps of force transmission, namely, the early rapid step, the stable step and the instable step, in which the stable force transmis- sion step accounts for 95 % of the whole process; （2） the relative slip evolution of the specimens is also divided into three steps, namely, the early rapid growth step, the stable growth step and the instable growth step; and （3） at the stable growth step, there exists a near-linear relationship between the relative slip of the specimen and the fatigue life. Finally, a fatigue damage model of the CFL-eonerete interface is proposed based on the stiffness coefficient. By using this model, the damage evolution law of the CFL-concrete interface in the fatigue process can be conveniently derived.