PSI - Issue 78

Paolo Petrella et al. / Procedia Structural Integrity 78 (2026) 2062–2069

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modelled with frame elements. The foundations were modelled with restraints at the base. The roof, that does not interfere with the structural response of the building, was taken into account in terms of load carried. The floors were considered rigid in their plane as the insertion of a steel bracing system of the floor fields is planned. Analyses were carried out with the limit state method, using the partial coefficients provided by codes. The actions considered for the design purposes include dead loads, permanent loads, variable loads, and are combined using the standard coefficients for two classes of combinations: (i) combinations of static actions at ultimate limit state (SLU); (ii) seismic combinations at life-safety limit state (SLV). Seismic analyses were carried out using non linear static analyses considering the different vertical distributions of the seismic action provided by the code and accidental eccentricities equal to 5%. 3.3. Designed works The following is a list of the interventions (Fig.4) planned to achieve the seismic adaptation of the building. Closing of existing niches and holes with a stitch-and-stitch procedure The procedure is aimed at reconstituting the wall structure in correspondence with tampering such as cavities and spaces of various kinds, created during the life of the building and can be traced back to that of the "stitch-and stitch" procedure. The reconstructions are carried out with solid block masonry appropriately bonded to the existing masonry both in the plane of the masonry and, if necessary, in its thickness. Consolidation of masonry with lime-based mortar injections To improve the mechanical characteristics of the poorest masonry, an intervention of injections of binding mixtures is planned. In these types of masonry, the presence of a significant quantity of voids has been detected. The injected mixtures are made up of pre-packaged superfluid mortars with a non-cement base, characterized by a low elastic modulus, compensated shrinkage, and chemical and physical compatibility with the existing masonry that is bound with lime and clay mortars. The injections are made at low pressure to avoid the expansion of the masonry. Consolidation of masonry with repointing and transversal connection of the facings The strengthening of the masonry walls (Fig.3) involves the insertion of artificial diatones made with unidirectional fabric in very high-resistance galvanized steel fibre, formed by micro-strands of steel produced according to the ISO 16120-1/4 2017 standard fixed on a micro-mesh in glass fibre, obtained from a width of fabric with certified technical characteristics. The intervention is carried out in the following phases: a) any restoration treatment of the damaged surfaces; b) creation of the entrance hole, with a size (diameter and depth) suitable for the nature of the subsequent connector, and subsequent removal of the mortar in the area adjacent to the hole created; c) packaging of the metal connector by cutting, “flaking”, and final rolling of the galvanized steel fibre fabric, with blocking of the same with a plastic tie; d) insertion of the connector inside the hole (number, anchoring depth, distances between centres to be carried out by a qualified technician); e) insert the polypropylene and glass fibre injector into the steel fibre diatone so as to bend the terminal part of the bow by 90°; f) collaboration of the connector by means of low-pressure injection of geomalta®, with certified technical characteristics, highly hygroscopic and breathable, hyperfluid, with high water retention based on pure natural lime, mineral geobinder® and controlled aggregates; g) fixing of the “flaked” strands, with concealment of the entire connector, and simultaneous pointing of the joints by means of geomalta® and so on, as in point f). Localized consolidation of masonry with natural basalt fibre mesh The strengthening of masonry walls (Fig.3) involves the use of an inorganic matrix composite system FRCM, made with balanced biaxial fabric in basalt fibre and AISI 304 stainless steel, with a special alkali-resistant protective treatment with solvent-free water-based resin. The intervention is carried out in the following phases: a) possible preparation of the surfaces to be reinforced, by demolition and removal of the existing plaster, repair of any lesions by stitching and/or consolidation with injection of fluid mortar and final dust removal by low-pressure hydro-washing; b) laying of a first layer of geomalta®, with a thickness of approximately 3 – 5 mm; c) with the mortar still fresh, proceed with the installation of the mesh, taking care to ensure complete impregnation of the fabric and avoid the formation of any voids or air bubbles that could compromise the adhesion of the fabric to the matrix or support; d) execution of the second layer of geomalta®, with a thickness of approximately 2 – 5 mm in order to completely enclose the reinforcing fabric and close any