The Lali Bridge crosses the Karun River, with this section being transformed into a reservoir formed by the presence of a new dam downstream. This cable-stayed bridge is located south of the city of Lali, in the Khuzestan province of Iran. It has a central span of 256 metres and two side spans each of 102 metres, for a total length of 460 metres.
The classic concept of a cable-stayed bridge was carefully optimised so as to consider the installation and service requirements as well as the particular conditions to which the towers are exposed, since they are either in the open air or partially submerged, depending on the water level in the reservoir. The pylons were founded on caissons cut into the rock walls of a deep gorge and were constructed of concrete with slipforms. The bridge itself is a composite steel construction with a deck of precast concrete elements joined by cast joints. It supports two lanes of traffic as well as oil and gas pipelines.
The structure’s behaviour during the strong earthquakes expected in the region was carefully studied by the professional team, particularly with regard to the hydrodynamic effects on the immersed pylons. For improved seismic behaviour and to reduce maintenance costs, the deck was monolithically anchored to the pylons. The dynamic behaviour under the action of the wind was validated by means of wind tunnel tests.
For this project, NCK was part of the engineering team for the development of the concept and was responsible for the certification of plans, studies, and estimates.