Valladolid, was the capital of the Spanish kingdom in the early XVII Century, and now is the seat of the regional Government of Castilla-León. As a new urban belt was to be built, we got the commission for the design of this crossing over the Pisuerga river, in which we regarded an opportunity for improving the urban quality of the South districts of the city.
The result is an urban cable stayed bridge with a quite special design, consisting mainly as two triangular, elevated concrete frames that, combining a compressed mast and a tensile stressed inclined “sail”, give rise to a carefully designed concrete “head” where the fan of stays born. The organization of the 30 m wide deck consist of two longitudinal concrete hollow-box girders, 25 m apart in the transverse direction, supporting transverse steel trusses spaced at 9 meters. The latter carry a set of longitudinal concrete top slab, of 18 cm thickness.
The main span of 120 m, flies over the Pisuerga, while the lateral counterweight span is 36 meters long. Its construction procedure was based on free cantilevering, with gentries able to accept girder segments of 9 m length.
The presstressed “sails”, conceived to substitute the classical backstays, reduce, thanks to their increased axial rigidity, the maximum bending moment in the main span due to live load to about one fifth of the bendings arising with normal backstays. Thus the greater difficulty in the erection of these impressive pieces is partially overcome by means of the improved static behavior of the structure.
The frames constitute concrete sculptures marking the entrance to the South districts of Valladolid. The bridge creates an architectonical space that is clearly perceived by the passerby. There are corners with particularly surprising views at the connecting zones of a sail, the lateral span girder and the counterweight. Somehow, this public work approaches the idea that concrete structures should have a minimum aspiration to become useful art.