As part of the structure replacement project carried out by the Subdirección Nacional de Carreteras del Instituto Nacional de Vías (an independent entity of the Ministerio de Transporte de Colombia), a new bridge over the Sogamoso River (Gabriel Turbay) was designed, it is located in the state of Santander Municipality of the La Fortuna – Bucaramanga Road (Route 45 crossing) at KP 17+760. The new structure replaces a suspension bridge with a span of 394 ft (120 m) that has become obsolete after 50 years of use.
After studying all the different constraints, several alternatives were considered from both a geometrical and structural point of view. The Administration chose a rigid frame bridge with three spans and an overall length of 626 ft (191 m) and a total width of 36 ft (11.20 m). The bridge has two traffic lanes 12 ft (3.65 m), two shoulders of 19’’ ft and 6 ft (0.50 m and 1.80 m) respectively, a sidewalk of 4 ft (1.2 m), and a curb of 1.15 ft (0.35 m).
The bridge structure is a ‘PI’-shaped portal frame with a center span of 394 ft (120.34 m) and two side spans of 98 ft (30.15 m) and 96 ft (29.51 m) respectively. The deck of the bridge consists of a steel-concrete composite section. The deck is a box-tub girder with variable height and a parabolic profile, which is longitudinally and transversally rigidified using flanges and bottom plates.
The portal frames of the bridge are comprised of two metal box-section columns and dividing box-section crossbeams. The columns are embedded in the deck. The lower connection of the columns was articulately designed during construction and embedded for superimposed dead loads and live load. This goal was achieved by using steel pins which allow bending over columns that are being built, and are being used as temporary supports. Once the assembly and pouring of the concrete slab has finished, side plates are placed with the purpose of achieving an embedding of the bending moment.