The original construction of the school is linked to the interventions undertaken by the Solvay Company, which settled in 1912 in the area of the Municipality of Rosignano Marittimo, now named after it, for the benefit of the community associated with the factory. The school, completed in 1923, initially housed only a few elementary school classes, but soon after, it also included a kindergarten.
After various expansion and elevation interventions, the building currently consists of an E-shaped structure, developed over two floors, plus a small three-story portion of approximately 100 sq m (a section of the building, above the main entrance, where the former caretaker’s apartment was located); the building’s load-bearing structure is original, consisting of a system of load-bearing masonry walls made of solid bricks, with an exposed brick finish, typical of the era.
The building has a gross floor area of 3050 sq m per floor, well-organized with a corridor acting as a distribution spine, off which classrooms and services open.
Considerations on the Current State of the Construction
The analysis of the design documentation and the geometric-structural survey activities conducted on the work in question have revealed the following:
- The masonry structure of the third class, characterized by hollow-core concrete floor slabs. Floor tie beams are absent;
- The masonry walls are generally well-interlocked at wall intersections and well-laid transversely;
- The structure exhibits good regularity and symmetry in terms of opening distribution: the masonry piers are generally continuous up to the top of the building.
Given the absence of a connection between walls and floor slabs, the provision of specific measures (metal ties) was immediately planned to prevent first-mode mechanisms (simple overturning, characterized by the lowest safety factors) and to ensure overall structural behavior.
Structure Modeling Criteria
The calculation of structural stresses and deformations, due to static and seismic load combinations, was performed using three-dimensional structural models developed with the Aedes.PCM software, Masonry Construction Design – 2023 version. Based on the contents of the original documentation and the results of the conducted investigation campaign, the global model of the building was refined. Regarding the two western end bodies, it is noted that the elevation changes in the foundation and roof were modeled; in general, everything was implemented to represent the geometry of the structures as realistically as possible. Generally, the complex has rather regular openings: all masonry piers have vertical continuity, which avoids incorrect eccentricities and ensures optimal behavior of the elements due to a correct vertical flow of loads. In addition to the foundation system, the soil stratigraphy was implemented, in accordance with the contents of the geological report; this made it possible to directly and consistently perform bearing capacity checks of the foundations with the superstructure loads.
Installation of Tie Rods
These elements have allowed for an improvement in the structural behavior of the building, ensuring an increase in box-like behavior, and also acting as restraint against out-of-plane wall overturning mechanisms. In particular, given the absence of a floor tie beam throughout the portion of the building constructed in the 1940s, this intervention is considered fundamental.
Stitch-and-Patch Interventions and Repointing of Mortar Joints
These two types of interventions were not conceived as widespread, but localized exclusively in areas where the masonry shows evident and localized degradation (cracks). The area subject to intervention was previously subjected to a thorough and careful diagnostic phase to evaluate the feasibility of the operation in relation to possible breakages or collapses. Work proceeded in successive sections in limited areas, avoiding weakening the existing building envelope. Regarding the repointing of joints, carried out by filling the joints with appropriate mortar (and eventual insertion of a stainless steel bar), it proved particularly suitable for application on the external load-bearing masonry of the building.
Reinforcement of Masonry Columns with Galvanized Steel Fibers
Analyses highlighted deficiencies in the flexural and shear strength of the masonry columns present on both the ground floor and the first floor. The intervention involved the application of a specific horizontal and vertical wrapping made with fiber tapes. The chosen system is an in-situ impregnated type; the fabric consists of galvanized steel fibers made with steel micro-strands fixed on a fiberglass micro-mesh, offering high tensile and shear strength, improving the resistance of structural elements subjected to high loads.
In-plane and Out-of-plane Reinforcement of Masonry Piers by Diffused Plating with Natural Basalt and Stainless Steel Fiber Mesh
The analyses highlighted deficiencies in the flexural and shear strength of a wall on the ground floor. The intervention involved the application of a heat-sealed, balanced biaxial mesh made of special basalt fiber and AISI 304 stainless steel microwires, which ensures stability and performance in both directions.
Slab Consolidation using Steel Profiles on the Underside
The hollow-core concrete slabs, which analyses showed did not meet the design loads imposed by current regulations, were reinforced on the underside by introducing metal carpentry profiles. The reinforcement consists of steel profiles arranged and distributed over the entire slab surface in two orthogonal directions: one parallel to the load-bearing ribs and the other perpendicular to them.
Anti-Slab Detachment Systems
Based on the results of the health report on slab detachment, it was possible to map the areas where intervention was necessary through the introduction of a specific anti-detachment system. The planned intervention involved the introduction of a protective system against detachment, achieved by fixing an electro-welded mesh (5 mm diameter, 10 cm x 10 cm grid) to the joists and/or the extradosal screed of the slabs using M5 mechanical anchors and washers at a rate of 4 per sq m.
Foundation Consolidation
Foundation consolidation was necessary for parts of the perimeter masonry piers of the building portion used as a kindergarten and for the spine piers of the school’s entrance area. For the consolidation of superficial foundations, a reinforced concrete tie beam was planned at the top of the entire foundation strip, serving to encircle the masonry pier and increase the contact surface with the ground. Additionally, a ‘nose’ connection of the lateral tie beams was created at regular intervals.
