ANIDIS - L'ingegneria Sismica in Italia, ANIDIS XX - 2025

Dimensione del carattere:  Piccola  Media  Grande

External steel bracing frames with energy dissipation devices for the seismic retrofit of a precast R.C. school building

Giada Frappa, Alessia Bernardotto, Samantha Lisetto, Margherita Pauletta

Ultima modifica: 2025-08-01

Sommario


The preservation of built heritage is of paramount importance for ensuring human safety, especially in the case of school buildings.

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. In addition to being highly effective, this method minimizes disruption to the building's ongoing activities.

This study presents a retrofit solution for a school building located in a high seismic risk area. The as-built structure, composed of precast concrete elements, lacks sufficient strength to meet the seismic and gravitational load requirements set by the Italian Building Code.

The proposed intervention includes the installation of external steel braced frames equipped with energy-dissipating devices. These frames increase the building's stiffness, thereby reducing displacements of structural elements. The corresponding increase in acceleration is offset by the dissipation of seismic energy through the installed devices.

The positioning of the steel frames along the building perimeter is chosen to regularize the seismic behavior by minimizing the eccentricity between the center of mass and the center of stiffness, thereby reducing the resulting torsional effects.

In addition, local strengthening interventions are proposed, like those increasing the shear strength of beams and columns and establishing a mechanical connection between the precast beams and columns, whose current interaction relies solely on friction.

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