PSI - Issue 78

Elisabetta Bersanetti et al. / Procedia Structural Integrity 78 (2026) 372–378

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The building is arranged around three internal courtyards, the largest of which is directly accessed from the main front (facing Piazza dell’Unità d’Italia), and is developed over three above -ground levels in addition to a basement floor. The levels are characterized by considerable ceiling heights; furthermore, in the western part where the representation halls are located, there is a zone of greater height compared to the others (approximately 9 m). All façades, both external and internal, are clad in marble slabs. All above-ground floors are currently in use, housing the offices of the Prefecture, the Police Headquarters, and, on the top floor, a large portion is occupied by the Livorno State Archives with its really important loads. The interior areas of the building identified as having monumental value include the entrance from Piazza dell’Unità d’Italia and the representation halls, with the related monumental staircase, located on the second floor above the entrance. The building also includes a basement level that extends over nearly the entire footprint of the structure, originally intended for the storage of equipment and animals. Over the years, this space has been almost entirely abandoned due to poor hygienic conditions. Some documents suggest the possible presence of an air-raid shelter beneath the main courtyard, but no confirmation has been found.

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Fig. 1: a) historical plan of the foundations and basement; b) Aerial view of the building and intervention area

The load bearing structure is primarily composed of solid brick masonry, with some mixed sections of stone and brick, mainly in the basement, where stone masonry predominates. Floor level tie beams have also been identified, though not consistently confirmed throughout. A small portion was constructed using reinforced concrete, with beams and columns. This construction difference is reasonably attributed to changes made during construction due to material shortages during the war period. The floors are made of reinforced hollow-brick slabs, placed at consistent elevations throughout the building. Laser scanner surveys were carried out on the building, with BIM-based restitution, along with historical research and investigations aimed at achieving a sufficiently in-depth knowledge framework. No significant cracking patterns were observed on the structure, only some material degradation and limited deformations due to local irregularities (small unsupported wall segments, slab deformations caused by the load of the State Archives, etc.). 2. Structural Behavior Analysis The first step involved the assessment of the building’s static and seismic vulnerability, conducted through both linear and nonlinear static analyses. The evaluations performed using the computational models highlighted a moderately adequate behavior under both static and seismic actions, considering the construction era and the geometric and structural features. However, this structural performance is clearly not compliant with the requirements of current technical standards. Although no changes in use are planned, the static behavior was still analyzed and found to be globally satisfactory, with only a limited number of elements, both masonry and reinforced concrete parts, failing to meet the verification criteria. A particularly delicate issue concerns the high slenderness of the masonry walls (over 9 meters in some areas), which does not satisfy the slenderness condition (λ < 20) required for Ultimate Limit State (ULS) saf ety checks in section 4.5.6.2 of the NTC2018. Eurocode, in contrast, adopts a more lenient limit of λ = 27. Given the absence of associated deformation or cracking patterns, it was agreed with the supervisory authorities that this geometric limitation should not be considered an obstacle to the static and seismic retrofit of the building. There are also deficiencies in the reinforced concrete (RC) structures that are typical of buildings designed without seismic criteria. Specifically, while cross-sections and flexural reinforcement are often substantial, they are not always sufficient, and there is a lack of adequate shear resistance. Regarding seismic behavior, the building exhibits generally fair performance beyond the elastic limit of the masonry structures (ultimate behavior at SLV – Service Life Limit State). Under these conditions, the masonry displays diffuse plasticization