Calabrese Angelo Savio, D'Antino Tommaso, Colombi Pierluigi, Carloni Christian, Poggi Carlo
Department of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, 20133 Milan, Italy.
Department of Civil Engineering, Case Western Reserve University, Cleveland, OH 44106, USA.
Materials (Basel). 2020 May 21;13(10):2368. doi: 10.3390/ma13102368.
Several reinforced-concrete (RC) structural elements are subjected to cyclic load, such those employed in highway and railroad bridges and viaducts. The durability of these elements may be reduced as a consequence of fatigue, which mainly affects the steel reinforcement. The use of externally bonded (EB) fiber-reinforced cementitious matrix (FRCM) composites allows the moment capacity to be shared by the internal reinforcement and the EB composite, thus increasing the fatigue life of the strengthened RC member. The effectiveness of EB FRCM composites is related to the composite bond properties. However, limited research is currently available on the effect of fatigue on the bond behavior of FRCM-substrate joints. This study provides first the state of the art on the fatigue behavior of different FRCM composites bonded to a concrete substrate. Then, the fatigue bond behavior of a polyparaphenylene benzo-bisoxazole (PBO) FRCM is experimentally investigated using a modified beam test set-up. The use of this set-up provided information on the effect of fiber-matrix interface shear and normal stresses on the specimen fatigue bond behavior. The results showed that fatigue loading may induce premature debonding at the matrix-fiber interface and that stresses normal to the interface reduce the specimen fatigue life.
一些钢筋混凝土（RC）结构构件承受循环荷载，例如公路和铁路桥梁及高架桥中使用的构件。由于疲劳，这些构件的耐久性可能会降低，疲劳主要影响钢筋。使用外部粘结（EB）纤维增强水泥基复合材料（FRCM）可使抗弯承载力由内部钢筋和EB复合材料共同承担，从而延长加固RC构件的疲劳寿命。EB FRCM复合材料的有效性与复合材料的粘结性能有关。然而，目前关于疲劳对FRCM与基体界面粘结性能影响的研究有限。本研究首先介绍了不同FRCM复合材料与混凝土基体粘结的疲劳行为的研究现状。然后，使用改进的梁试验装置对聚对苯撑苯并双恶唑（PBO）FRCM的疲劳粘结行为进行了试验研究。该试验装置的使用提供了纤维-基体界面剪应力和正应力对试件疲劳粘结行为影响的信息。结果表明，疲劳加载可能会在基体-纤维界面处引起过早脱粘，且垂直于界面的应力会降低试件的疲劳寿命。
