PSI - Issue 44

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I. Boem et al. / Procedia Structural Integrity 44 (2023) 1260–1267 Boem I. and Gattesco N. / Structural Integrity Procedia 00 (2022) 000–000

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c d Fig. 4. F h -  h curves in samples (a) vRE-C, (b) vRE-F, (c) vRI-C and (d) vRI-F. The numerical curves are also reported in black lines. The two samples reinforced at the extrados (Fig. 4a-b) showed very similar performances, with approximately symmetric behavior in positive and negative loading direction and tri-linear backbone curves. At about 4-5 kN, cracks sequentially formed at the spring sections and at two opposite haunch sections; this determined a first visible stiffness reduction of the F h -  h . curve, in the range within  h ~15 mm. Then a further consistent stiffness decrease was observed; likely related to the beginning of the gradual slippage of the metallic anchors in tension, at the spring sections. As the test prosecuted, several cracks formed in the plaster at the extrados, almost parallel and oriented in the longitudinal direction of the vault. Even at the intrados, some cracks occurred, mainly in the mortar joints. At the end, the tensile failure of the embedded reinforcement was reached in correspondance of a haunch section. At this occurrence, the peak load reached by sample vRE-C was 11.8 kN, in correspondance of a displacement  h = 115.5 mm; vRE-F attained 10.8 kN at  h = 86.5 mm. The effectiveness ratios resulted 21.5 and 19.6, respectively, for the CRM and the FRCM technique. In Fig. 5 the global view of the vaults at ultimate displacement and some crack details at the haunch section where the fibers failure occurred are illustrated.

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b c Fig. 5. Global view at ultimate displacement in vRE-F (a) and some cracks details in (b) vRE-C and (c) vRE-F.

The performances of the samples reinforced at the intrados (Fig. 4c-d) resulted generally lower than the respective extrados application, in terms of both resistance and displacement capacity. The backbone curves approximately followed a tri-linear behavior, with former cracks at the spring sections (at about 4-5 kN), followed by the cracking of two opposite haunch sections, with a consequent stiffness reduction. However a marked unsymmetry of the F h -  h

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