PSI - Issue 44

Rebecca Fugger et al. / Procedia Structural Integrity 44 (2023) 2166–2173 Author name / Structural Integrity Procedia 00 (2022) 000–000

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and 3.3 N/mm 2 and 4.4 N/mm 2 for T9-L and T15-L. After that, a combined failure mode occurred, consisting of out of-plane buckling of the mortar layer and some yarns break at their loaded ends. 3.2. Displacements and crack pattern detection using Digital image correlation Fig. 5 shows the crack pattern of the composite system in the proximity of fracture. Real crack pattern is shown in Fig. 5a together with the one detected through DIC, both with the vertical displacement (u v ) and vertical tensile strain (ε v ) fields. Starting from the creation of the first horizontal crack, all cracks that developed during the test can be clearly seen through DIC (Fig. 5b-c). In particular, for the displacement field cracks can be found at the boundaries between two different colors, while, in the strain field where is a discontinuity between zones with zero vertical deformation. A good correspondence can be observed between the crack pattern observed visually on the surface of the specimens and those detected by DIC.

Fig. 5. Crack pattern of composite specimens (a) before reaching the shear strength; (b) corresponding vertical strain and (c) corresponding vertical displacement field obtained through DIC. 4. Conclusions Bare textile specimens, both T9 and T15, demonstrated to have a sensibly lower shear strength per unit width (τ* max ), with respect to that achieved from matrix specimens (τ* max is about 4.59 kN/m for T9, 5.63 kN/m for T15 respect 66.43 kN/m for cement-based mortar and 24.16 kN/m for lime-based mortar). Nonetheless, there is a clear increment in shear strength per unit width is observed for both types of mortar, in particular for T9-C and T15-C, τ* max is equal to 70.1 kN/m and 86.27 kN/m respectively and for T9-L and T15-L, τ* max is equal to 32.9 kN/m and 43.86 kN/m respectively, due to the presence of the textile in the composite specimens. In addition, the composite specimen with T15, thanks to the larger free space between yarns, achieved the maximum τ* max . Hence, there is also a composite enhancement effect ensured by a better adhesion between the two layers of the mortar. On the other hand, the shear stiffness of the composite, is not influenced by the presence of the textile. Acknowledgements This work was carried out within the Research Projects “DPC-ReLUIS”, funded by the Italian Department of Civil Protection (2019-2021) and “RIPARA Integrated systems for the seismic protection of architectural heritage” funded by Regione Lazio (2021-2023). Funding is also acknowledged from the Italian Ministry of Education, University and Research (MIUR), in the frame of the Departments of Excellence Initiative, attributed to the Department of Engineering of Roma Tre University (2018-2022). References American Concrete Institute (ACI) 549, 2020. Guide to design and construction of externally bonded fabric-reinforced cementitious matrix (FRCM) systems for repair and strengthening concrete and masonry structures, ACI 549.6 R-20. Farmington Hills, MI, US. American Society for Testing and Materials, 2007. ASTM E519-07. Standard Test Method for Diagonal Tension (shear) in Masonry Assemblages.