PSI - Issue 78

Giada Frappa et al. / Procedia Structural Integrity 78 (2026) 17–24

18

of plan and/or elevation irregularities (Frappa and Pauletta, 2025). Furthermore, many of these buildings fail to meet the safety requirements for gravity loads as specified in the current Italian building code. Consequently, one of the primary challenges faced by structural engineers today is the design of effective strengthening interventions for existing buildings. These interventions aim to ensure structural stability under both gravity and seismic loads, thereby avoiding the need for costly demolition and reconstruction. The demand for practical and non-invasive seismic strengthening solutions has led to the development of innovative techniques. For reinforced concrete buildings, one such technique involves the installation of external steel braced frames positioned adjacent to and/or perpendicular to the building façades (Erdil et al., 2024; Ferraioli et al., 2025; Frappa and Pauletta, 2022). In addition to being highly effective, this method minimizes disruption to the building's ongoing activities. The use and effectiveness of such reinforcement systems are demonstrated through the development of a case study presented herein. 2. Building description The subject of this study is a building forming part of the “Aldo Moro” school complex, located in the municipality of Resia, Italy. Constructed in 1978, the structure presents a regular rectangular floor plan measuring 45.20 m × 15.40 m measured externally to the façade cladding panels (Fig. 1), and comprises two stories with a total above-ground height of 7.00 m at the top surface of the attic floor system.

(a) (b) Fig. 1. (a) View of the building; (b) ground floor plan (from documents provided by Resia Municipality).

The structural layout is geometrically regular in plan (Fig. 1b), featuring spans of 7.20 m along the Y-axis and spans of 6.00 m and 7.20 m along the X-axis. The primary load-resisting system consists of precast Reinforced Concrete (RC) moment-resisting frames in the X direction, complemented by RC shear walls, located in the Y direction, which are highlighted in red in Fig. 1b. The foundation system comprises precast RC socket-type footings designed to house vertical elements via a steel centering insert placed at the base. These footings are interconnected by RC tie beams with a square cross-section of 300 × 300 mm². The precast RC columns have a constant cross-section of 440 × 440 mm². Their longitudinal reinforcement comprises 26 mm diameter bars placed at the corners, with additional 26 mm bars on the faces for central columns and 20 mm bars for perimeter ones (Fig. 2). At floor levels, the columns are equipped with corbels to support the beams.

(a) (b) Fig. 2. Typical cross sections of (a) central column; (b) perimeter column (from documents provided by Resia Municipality).