Viaduct over the river Ulla

Abstract

The Ulla Viaduct is the crossing of the N-NW Spanish High Speed Railway over the Ulla-Deza Fluvial System", Place of Community Interest (LIC), with height above that level of 115 m. Strong winds are usual in this valley. The viaduct is 630 m long. A lightly pointed arch, 168 m of span and 105 m of rise, crosses over the river. The access viaducts are made of spans that are 52 m length each. The deck is a prestressed concrete box, 3,89 m height constant. It is made using a selfcast formwork. The arch itself is a box section, dimensions 7,7 × 3,50 m the arch axis is a polygonal line. The concrete of the arch is poured on site using a self-launnching formwork girders and the aid of 24 temporary stay cables. The piers over the ground have a variable box section. The piers over the arch are constant cross section columns. The shape of both, the main piers and the piers over the arch, are laterally rounded in order to reduce the effect of the wind loads. The efficiency of the adopted shapes has been verified using wind tunnel tests."