“Fondo de Adaptación”, seeking to rehabilitate the hotspots of the road Málaga – Los Curos, proposed the construction of 850 m in bridges (3 structures). Hisgaura will be the longest bridge of this project which will improve the connection between the provinces of Boyaca and Santander.
Pedelta proposed an Alternative Construction Design of a 653 m long cable-stayed bridge over the Hisgaura Gorge in the State of Santander (Colombia). The bridge has a main span of 330 m, two back spans of 125 m each and two approach spans of 36.5 m each. The elevation reaches heights over 120 m above the bottom of the valley. The deck, 13.7 m wide, accommodates 2 traffic lanes and is suspended on two lateral stay planes. The deck consists of two longitudinal prestressed concrete girders -1.40 m in depth- which are supported by the stays spaced at 10 m, with floor beams 5 m apart, supporting the concrete deck.
The inverted Y-shape towers reach 70 m high above the deck level and consist of two concrete pylons connected with transverse concrete girders in a classic “H” below the deck. The highest tower is 148 m tall. The north abutment and the intermediate pier take the back stays uplift force and allow longitudinal movements of the deck.
This bridge concept was the preferred option after a study on a set of cable-stayed bridge alternatives, which included various bridge span configurations, tower types, and materials. Highly variable foundation conditions at the site represented one of the major challenges to assess the most cost-effective solution. During the study of alternatives, Pedelta conducted the preliminary design (30%) of two cable-stayed bridge alternatives with a main span of 416 m and 330 m, respectively.
Special considerations were taken in the design in order to address high seismic demands and slope instability issues along the valley. A time history analysis was carried out to evaluate the seismic effects. Higher forces than the ones evaluated with a simplified modal analysis method were found. Four seismic dampers, 2500 kN capacity each, were designed to optimize the seismic behavior of the bridge. A reduction of 50% in the seismic force has been reached by the use of the seismic dampers. A wind engineering analysis including laboratory sectional wind tests and a wind climate analysis was carried out to prevent aerodynamic instabilities.