Tahuando Bridge in Ibarra

Key facts

This 290 m central span cable-stayed bridge is part of the north section of Ibarra ringroad. This bridge was put forward as the solution to span across a 180 m deep gorge, without requiring support and access from the bottom of the gorge during construction. To achieve this, the main span is constructed as cantilevered deck sections tied back to the pylons with the stay cables. The total length of the bridge is 430 m and the pylons stand 65 m above the deck.

The challenge that the seismic action imposed on a bridge of this significance, in a country located between the Nazca and South American tectonic plates, was addressed by implementing the following strategies in the design:

– Resisting low intensity and frequent earthquakes as an isolated and dampened bridge

– Allowing the bridge deck to be horizontally restrained against the pylons following an elastic response for the design earthquake

– Taking advance of the abutment’s passive resistance and the limited ductility at the base of the pylons in the case of the maximum credible earthquake event.