PSI - Issue 78

Vincenzo Calvanese et al. / Procedia Structural Integrity 78 (2026) 1134–1142

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These new masonry sections will be connected to the Horrea's load-bearing elements through perforations (8-10 mm diameter hole, 6-8 mm bar diameter). This will re-establish continuity between the new masonry and the existing structure. Finally, the remaining facade walls, after being sealed with fluid mortar injections, will be connected to the vault-supporting walls. This will be achieved through 18 mm diameter AISI 304 stainless steel bars inserted into 20 mm diameter holes. The precise location of these connections will be determined based on the specific conditions encountered on site. Figs. 5 and 6 show the details defined on site. Another interesting intervention is the consolidation of the front wall of the Bath of Sarno. It is very complex, having been caused by the significant damage of the impact of the pyroclastic flow during the eruption of AD 79. This impact caused overturning and deformations, resulting in the clear out-of-plumb position of the facade. This impact also led to a detachment of the front wall from the lateral walls. At the lower level, several lunettes are present. These lunettes have a poor material, the masonry in the lunette sections was depleted during the impact of pyroclastic event and subsequently crushed. The resulting sequence of vertical cracks directly indicates a crushing failure. The primary step of the interventions is to consolidate the masonry at the lower level. This will be achieved through a system of injections that will homogenize the masonry (injections and reinforced perforations). The reinforced holes will have a length equal to three-quarters of the wall's thickness. The boreholes will be 10 mm in diameter, and the helical bars, 12 mm in diameter, will be installed without injection mortar, relying instead on percussion. These helical element insertions will resist to bending movements and shear forces through friction between the stainless steel and the masonry. The masonry will consolidate areas where the structure was altered by this compression-bending phenomenon, which manifested the characteristic vertical cracks. All these interventions then need an evaluation of efficiency though a new diagnostic campaign and continuous monitoring as explained in the flowchart in Fig. 2.

Fig. 5 Structural details defined on site

Fig. 6 Details of the interventions in the Horrea