PSI - Issue 44

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Marta Del Zoppo et al. / Procedia Structural Integrity 44 (2023) 2158–2165 Del Zoppo et al./ Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 6. (a) FRM_2S specimen, (b) deformed shapes, (c) capacity curves. The deformed shapes derived from the LVDTs records are in agreement with those derived for the URM specimen, given the same location of the crack. The peak load achieved by the specimen is 66 kN, corresponding to the opening of the horizontal crack in the FRM on the side in tension of the wall. After the cracking, a sudden degradation of the out-of-plane capacity is observed leading to the failure of the specimen. 3.4. Discussion of results To assess the effectiveness of the FRM system, the experimental results are herein compared. In terms of deformation capacity, the experimental deformed shapes corresponding to an external load of 30 kN are compared in Fig. 7a. The plot shows that the out-of-plane deformation capacity of both strengthened panels, FRM_1S and FRM_2S, is significantly lower that of the URM panel. This is partially related to the cross-section enlargement due to the strengthening system (i.e., thickness of URM panel = 120mm, thickness of FRM_1S=135 mm, thickness of FRM_2S=150 mm), but also to the effect of the FRM itself that limited the development of the cracks in the masonry. This is clearly visible from Fig. 7b, which shows the comparison in terms of force-displacement curves at the mid-span of the specimens. The performance of FRM strengthened specimens is almost linear elastic up the formation of the first crack in the FRM layer, and the out-of-plane stiffness of both strengthened walls is quite similar. Conversely, the performance of the URM wall is clearly nonlinear due to the progressive damage of the