Structural Rehabilitation Work On The Viaduct Over The River Po On The A7 Motorway

Abstract

The work consisted of the static and seismic retrofitting of the bridge over Po River, on northbound carriageway of highway A7, managed by Milano Serravalle Milano Tangenziali S.p.A. under concession of Italian ministry of transportation. The bridge, designed in the 1960s, is made of reinforced concrete, 800 m long, and consists of 11 identical spans, each with a length of about 69 m. The deck width is 18.4 m, of which 14 m is available for traffic.Over the years, the structure has undergone various strengthening and restoration works, of which the most important took place in 1992, when an integrative slab was built over the existing deck and an external cable pre-stressing system was installed for both the caissons and the buffer beams.The continuous inspections of the structure detected deterioration in various parts of the structure, as well as defects in the realization of the pre-stressing system, which has significantly lost its effectiveness.This article will describe the results of the in-depth investigations carried out on the viaduct, the design of the static and seismic interventions of retrofitting, to restore the structure to a level of complete adequacy to current regulations, and the methods of carrying out the works.