PSI - Issue 78

S. Cattari et al. / Procedia Structural Integrity 78 (2026) 1577–1584 Author name / Structural Integrity Procedia 00 (2025) 000–000

1583

7

techniques adopted for URM strengthening in the current database sample.Similarly, for RC structures, both traditional and innovative strengthening techniques are observed. For example, jacketing is a traditional method for strengthening RC columns, involving section enlargement through a new hollow concrete casing properly reinforced with longitudinal and transverse bars to work integrally with the original section. More advanced approaches include strengthening with composite materials, such as polymeric resin-based matrices combined with high-strength carbon (CFRP) or glass fibers (GFRP). These innovative techniques are now widely adopted, as confirmed by the analysed sample (Fig. 5b).

a)

b)

Fig. 5. In-depth study of the different intervention techniques that can be designer for reinforcement of masonry walls (a) and the reinforcement of RC columns (b)

The matrix presented in Table 1 provides an overview of the most common types of interventions used to improve the seismic performance of load-bearing structures. However, interventions targeting the existing vertical and horizontal structural system are not the only adopted strategies for seismic improvement. In fact, additional types of interventions emerged from the analysed sample, as illustrated in Fig. 6. Among these, the addition of new seismic resistant elements proved to be particularly significant. In URM structures, this includes the addition of new load bearing walls (present in 33% of the structural units in the database), whereas in RC structures, the intervention typically involves the introduction of new RC shear walls or the installation of bracing systems. The use of external seismic exoskeletons is also an emerging technique, often applied to RC buildings – particularly school facilities – where design constraints include not only the need to improve structural capacity but also operational requirements such as avoiding the evacuation of classrooms and, in some cases, performing work during the school year. Additional interventions currently identified only in RC structures include the insertion of seismic joints, which serve to seismically separate a building into two distinct structural units, thereby mitigating the effects associated with plan irregularities. With regard to non-structural elements, in RC buildings, interventions mainly consist of anti-overturning measures for infill walls, while in URM buildings they focus on the replacement or securing of suspended ceiling systems.

Fig. 6. Other structural interventions in the analysed database of school buildings