PSI - Issue 78

Alberto Lemme et al. / Procedia Structural Integrity 78 (2026) 293–300

298

Fig. 7. Camorcanna vault before intervention Detail of woven cane and Intervention reinforcing the camorcanna with steel crossbands

Considerations on the rigidity of the decks In existing buildings, the regularity in plan and elevation is not always respected and the stiffness of the decks can affect the behaviour of the buildings. A very frequent mechanism is the ejection of the angle located in the connection strip between two adjoining walls. Separation of part of the angled section occurs when the interaction of forces acting on minor orthogonal panels causes the angled section block to rotate out of plane with its hinge point at a lower height. The mechanism is favoured by actions with a horizontal component and the presence of rigid horizons that counteract the natural deformation of the masonry cell, determining a concentrated out-of-plane action at the corners. In this case the seismic improvement intervention must control all the first-mode mechanisms with floor connections realised with chains, steel angle profiles arranged on the perimeter and no rigid slabs must be realised on the extrados. Another relevant aspect is the regularity in plan of the structures and in elevation, which can have different configurations, and among these it is very frequent to have rooms with a high length without transversal walls, as in the case of many places of worship or public buildings. In the case of the high school in Via Maiella in L'Aquila, the building complex consists of three buildings separated by joints, of which the central body is constrained under Legislative Decree 42/2004 and in its original conformation has an elongated rectangular shape with a ratio of approximately 6.5 between the sides (11 m x 70.50 m). The irregularity in elevation and in the distribution of transversal stiffnesses means that as a result of dynamic thrusts, the building rotates around the area that has a greater height, hinging with a displacement that induces high tensions in the longitudinal masonry. The interventions foreseen were: solid brick brakes above the vaults, reticular beams and steel profiles connecting the first floor, ring reinforcement of the slender masonry, increase of the mechanical characteristics of the masonry in line with reinforcement made of basalt fabric and transversal connections. The modal analysis of the design situation shows a significant reduction in deformations.

Transverse s�ffening interven�on

Dra� structural model with steel reinforcement

Soundproofing view of the steel reinforcement elements

Modal analysis a�er interven�on

Fig. 8. Interventions on the decks.

In the cases examined, the interaction with the historical-artistic apparatus and the structural peculiarities of the buildings do not always make it possible to achieve an acceptable level of safety (at least 60%), and even if the standard allows exceptions for these buildings, the problem of seismic safety in relation to public use remains. In the interventions illustrated, the reinforcement and consolidation of the structures and decorative apparatuses was carried out by intervening on the capacity to seismic actions of the building bodies and apparatuses.