Soto de Ribera Bridge

Name and location
Cable stayed bridge over the Caudal river, in the municipality of Soto de Ribera, Asturias (Spain).

Key features
Tipology: Cable stayed bridge of two main spans of 93m. Deck made of precast elements.
Total Length: 204m (9m + 93m + 93m + 9m)
Average height: the deck is 10m above the river and 20 m above the existing railway tracks. Pylon 38m high over the deck.
Use: Road
Materials: Reinforced concrete for the tower and prestressed precast “U” beams plus concrete compression slab “in situ” for the deck.
Construction: Assembly of the precast elements supported on temporary steel towers, and then cable stays stressing.

Gobierno de Asturias. (Asturias Government, Spain).


BT Intervention
Project tender.

General information
Construction pictures

General information

In order to decrease the cost of the structure and reduce the number of cables and the height of the tower, two small 9m spans are disposed at the entrance and exit of the bridge. Therefore, the final spans are: 9 + 93 + 93 + 9m . These compensation spans stiffen the deck in the furthest area from the tower, where the cables are less effective against overload and help to control the bending moments .

The fixed point of the deck is in the tower, creating a continuous lintel with only two joints in the abutments at the entrance and exit of the bridge .

This solution requires the deck to be vertically bracket by vertical prestressing tendons that compress the sliding support bearings. These tendons must acquire significant horizontal movement capability by appropriate construction details.

The board is 11.65 m wide with a cross-section formed by two edge precast ribs, 1.50m depth and 2.00 m wide at its bottom. A variable thickness slab between 20 and 35 centimeters is poured at the top. Thus the total depth is 1.85 m in the axis of the bridge. The board is suspended by two planes of cables, each plane located at the edge of the board. Cables are approximately spaced 10.00 m . The choice of this cross section has been motivated by criteria of structural efficiency, economy of materials, constructive simplicity, shortening execution time and reducing the number of straps. Besides that, it is a classic bridge section, quite slender, reducing bending efforts. This slenderness requires the use of temporary supports for mounting the deck, as if it was mounted on cantilever would be required at least 2.50 m of total depth.

The precast beams come with pre-tensioned reinforcements from the workshop. During the construction process, once they are placed on the temporary supports, the beams are longitudinally linked by prestressing bars to then threading a few tendons, which are spliced to one side of the joints, straining and completing its prestressing in order to resist the flexo-compression efforts of the deck.
The morphology of the tower has been conditioned by the criterion of easiest construction, what reduces the cost and enhances the constructive performance, reducing the construction time. From that point, and following simple criteria of architectural composition, an “H” tower is projected with a completely vertical shaft, what allows to be constructed using climbing or sliding formworks. Horizontal braces, executed after the climbing/sliding process, control the efforts and horizontal movements caused by the wind actions crossing the line of bending moments in the shafts and impeding the rotation in the joints.


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General definition

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Longitudinal sections general definition

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Cross sections general definition

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Construction pictures