In the last decades, the increasing need for strengthening and retrofitting of existing masonry members has led the scientific community toward the development of innovative strengthening systems. Among these systems, inorganic-matrix composite materials have been gaining increasing popularity due to their effectiveness, relatively low cost, ease of the application, and reversibility of the intervention. Inorganic-matrix composites, usually referred to as fiber- (or fabric-) reinforced cementitious matrix (FRCM) composites, were successfully used as externally bonded reinforcement (EBR) of masonry members subjected to various load combinations. However, their effectiveness is strictly related to the FRCM-substrate bond behavior. Therefore, numerous set-ups were employed to investigate the bond properties of FRCM composites. Among them, single-lap direct shear test set-ups were the most commonly employed and are now recommended by available design guidelines for FRCM composites.

In this paper, a modified beam (MB) test set-up is used to study the bond behavior of two different FRCM composites: a polyparaphenylene benzobisoxazole (PBO) FRCM and a carbon FRCM. The parameters studied are the dimensions of the blocks used in the MB tests and the presence of bare or embedded fibers at the gap between the blocks. The bond behavior observed is compared with that of single-lap direct shear tests of the same FRCM composites. The results obtained provide an insight on the influence of normal stress components at the matrix-fiber interface on the FRCM bond behavior, which may play an important role in the capacity of FRCM strengthened curved members.

在过去的几十年中，对现有砌体构件进行加固和翻新的需求日益增加，这促使科学界开发了创新的加固系统。在这些系统中，无机基复合材料由于其有效性，相对较低的成本，易于使用和干预的可逆性而日益受到欢迎。无机基质复合材料，通常称为纤维（或织物）增强水泥基（FRCM）复合材料，已成功用作承受各种荷载组合的砌体构件的外部粘结增强材料（EBR）。但是，它们的有效性与FRCM-底材的键合行为密切相关。因此，采用了许多方法来研究FRCM复合材料的粘结性能。其中，

在本文中，使用改进的梁（MB）测试装置来研究两种不同FRCM复合材料的键合行为：聚对亚苯基苯并双恶唑（PBO）FRCM和碳FRCM。研究的参数是MB测试中所用块的尺寸以及块之间的间隙中是否存在裸露或嵌入的纤维。将观察到的粘结行为与相同FRCM复合材料的单圈直接剪切测试进行比较。获得的结果提供了对基体-纤维界面处的正应力分量对FRCM粘结行为的影响的见解，这可能在FRCM增强的弯曲构件的承载能力中起重要作用。