Renovation and expansion of the municipal building in Ponte in Valtellina (SO)

The building was designed and constructed in the early 1940s, featuring a functionalist rationalist style characteristic of the period. It is subject to heritage protection.

Preliminary to the design phase, diagnostic investigations were carried out directly by the technicians of FOPPOLI MORETTA e ASSOCIATI s.r.l.. The investigations allowed the achievement of knowledge level LC3.

The structural project included the following interventions:

• Demolition of the perimeter masonry above the access stairs to the town hall;
• Creation of new openings and infill of existing openings with seismic-resistant masonry in the main building;
• Construction of a two-way reinforced concrete slab in front of the rustic building adjacent to the former “cinema” and construction of retaining walls on the north and south sides (with seismic joint) to support the slab;
• Construction of reinforced concrete elevator shaft, access ramps, and connecting walkway to the square;
• Installation of roofing canopies;
• Demolition and reconstruction of the existing slab and roof of the rustic building and the west-side wall on the first floor, construction of a mezzanine slab, infill of existing openings, and construction of load-bearing masonry to support the new slab.

The structure was upgraded to meet seismic load requirements according to the 2008 Italian Building Code (D.M. 2008) by executing necessary connections between floors and vertical structures and reinforcing the most stressed masonry piers with fiber-reinforced lime mortar panels.

A level LV3 seismic vulnerability assessment was carried out. The analysis was based on the following regulatory parameters:

• Building type: 3 (strategically important structure)
• Usage class under seismic actions: Class IV (construction with significant occupancy)

The analysis was performed using three-dimensional numerical modeling, representing masonry with shell/plate finite elements. The seismic verification was carried out using linear static analysis.

Intrinsic nonlinear behavior of the masonry was accounted for by identifying crack patterns and representing the resulting discontinuities in the model, validated through recursive comparison with the calculated tensile stresses.