PSI - Issue 44

Ingrid Boem et al. / Procedia Structural Integrity 44 (2023) 2238–2245 I. Boem, B. Patzák, A. Kohoutková / Structural Integrity Procedia 00 (2022) 000–000

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In the sample strengthened on one side only, the damage at the corners and at the center of the panel started almost simultaneously, at about 130 kN, with a consequent reduction of the capacity curve stiffness (Fig. 6a). The peak load was reached at 12 mm and was equal to 155 kN (corresponding to an increase of 36% in respect to the unstrengthened sample). Then, the load decrease was gradual, due to CRM: the ultimate displacement was 26.3 mm (drift 1.3%). The diagonal cracking failure mechanism mainly activated (Fig. 6b), according to the experimental test, but also elevate tensile strains were recorded at the corners.

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Fig. 6. Capacity curves and principal tensile strain at ultimate displacement for the sample strengthened with CRM at one side only.

4. Out-of-plane bending test The out-of-plane bending test concerned a double-wythe rubble stone masonry sample having nominal dimensions 1030x2480x350 mm 3 (width x height x thickness) - Fig. 7a, arranged between an upper and a lower reinforced concrete beam (cross section 350x250 mm 2 ) and subjected to three point vertical bending (span 2730 mm). The CRM reinforcement was applied on one side only of the masonry; 8 GFRP L-shape connectors and 6 artificial diatones (stainless steel treaded rods inserted in fabric sleeves injected with grout) were installed. Out-of-plane loading cycles at increasing displacement were applied by pushing and pulling the sample horizontally, at the mid height. Further details and discussion about this experimental test can be found in Gattesco et al. (2022).

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Fig. 7. Out-of-plane bending test: (a) main characteristics of the sample and (b) schematization of the numerical model.

The numerical model is schematized in Fig. 7b: the masonry wall and the reinforced concrete beams were modelled through the 20-nodes brick elements, with the multi-layer cross sections defined for the CRM strengthened masonry. The presence of the GFRP connectors and the artificial diatones were considered, in a simplified way, by connecting the nodes at the opposite wall faces with axial rigid links. Perfect bond was assumed between the masonry and the RC beams. The self-weight was at first introduced and then maintained constant; then the horizontal load at the mid-height