PSI - Issue 44

Gabriele Guerrini et al. / Procedia Structural Integrity 44 (2023) 2214–2221 Gabriele Guerrini et al. / Structural Integrity Procedia 00 (2022) 000–000

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Fig. 1. Test specimen dimensions. Units of cm.

Specimen P1 was strengthened on both sides with CRM (Fig. 2a) consisting of GFRP meshes within a M15-class hydraulic lime mortar. Vertical GFRP bars (weft) were spaced at 120 mm and horizontal bars (warp) at 80 mm, for a total mesh weight of 400 g/m 2 . The nominal thickness of 30 mm could not remain constant throughout the wall, to obtain a flat finish over the stone masonry irregular surface. The CRM layers were mechanically connected to the wall by a total of 18 helicoidal steel bars (Fig. 2b and 2c) passing through both masonry leaves, 8 of which were located within the pier. Instead, an FRCM system was applied to both faces of specimen P2 (Fig. 2d). A PBO textile weighting di 22 g/m 2 in each direction was embedded in a M20-class, glass fiber-reinforced cement mortar. The nominal thickness was 10 mm and the irregular stone masonry surface resulted in a wavy finish of the FRCM. Fig. 2e shows the anchorage of a typical PBO through connector (joint) between FRCM and masonry. A total of 11 joints were provided, 5 of which located within the pier (Fig. 2f). 2.2. Material properties Natural stones were cut from Credaro-Berrettino calcareous sandstone rocks in the province of Bergamo, Italy. According to the quarry documentation, they are characterized by mean density of 2580 kg/m 3 , mean compressive strength of 149 MPa perpendicular and 144 MPa parallel to the sedimentation layers, and mean tensile strength of 19 MPa. Compressive ( f mc ) and tensile ( f mt ) strengths of masonry and jacketing mortars (CEN, 2006) are shown in Table 1, while Table 2 summarizes the mean masonry properties obtained from vertical (CEN, 1998) and diagonal compression tests (Frocht, 1931; RILEM, 1991; ASTM, 2015) on stone masonry wallettes (Guerrini et al., 2021b). Compressive strength ( f c ), elastic modulus ( E ), Poisson’s coefficient ( ν ), and shear modulus ( G ) were all obtained from vertical compression tests, while the tensile strength ( f t ) was evaluated from diagonal compression tests. The GFRP meshes embedded in the CRM strengthening of specimen P1 were characterized by mean tensile strengths of 74 kN/m and 86 kN/m in the weft and warp directions, respectively. Based on the manufacturers’ technical sheets, the mean tensile strength was 16 kN for the helicoidal steel connectors. The bidirectional PBO textile used for FRCM jacketing of specimen P2 was certified with a mean tensile strength of 45 kN/m each way. The mean tensile strength of PBO joints was certified as 26 kN.