Viaducto sobre el río Arnoia

A High Speed Train Viaduct ,1014 m long divided into two parts. The first, 802 m long and 55 m maximum span, was in situ built with movable scaffolding. The deck running over the river Arnoia rests on a 110 m span pointed arch. The second, 212 m long and 37 m maximum span, was built with a precast deck to cross the current Zamora – Orense railway line with a pronounced skew. The deck in the first part is formed by a continuous prestressed concrete beam with a constant depth of 3.65 m. Its cross section is box shaped with a bottom width of 5.50 m and 3.58 m side overhangs. The section was cast in two stages in order to simplify the interior box formwork and its movement. The piers are hollow reinforced concrete prisms with a flat octagonal cross section, inscribed in a rectangle 3.40 m deep by 5.50 m wide. The maximum pier height is 57 m at the arch springers. The piers have a pair of bearings in their head which restrict torsion. All bearings are longitudinally guided sliding POT except the fixed bearings in the piers adjacent to the arch. A 110 m span, reinforced centre arch was built for crossing the river Arnoia. This arch is formed by two semi-arches built in a vertical position and then lowered to their final location. The arch cross section is constant along its whole length and is formed by a hollow rectangle 3.60 m deep and 5.50 m wide. The arch acts as the deck’s fixed point for the whole viaduct. The deck is joined to the arch by means of a buffer inserted into the bottom slab of the box cross section. The precast deck cross section is formed by two juxtaposed, U shaped beams looking like a single box from outside. The deck is joined to transversal beams at the points closest to the current railway line. These beams are framed with the precast longitudinal beams. To the effects of longitudinal movements only, the prefabricated deck is joined to the main viaduct’s deck by means of prestressed bars.