In the new road heading from Kvesheti to Kobi, in Georgia, one of the bridge sites, is located in a deep valley where the difficulty of the access combined with steeply slopes suggested the development of an arch type bridge solution. Due to the extensive experience and successful in this field Arenas & Asociados was commissioned to collaborate in this unique task.
The arch has been designed with a main span of 285.00 m. The arch rises up to 51.50 m. The deck is supported on a set of pillars and spandrel columns spaced 19.00 m, being the span length the same both in the approach viaducts and over the main arch. This span arrangement intends, first to set out enough supports over the arch in order to guarantee its good antifunicular behaviour with a curved (not polygonal) geometry and, second, to allow the use of a cantilever construction method with temporary diagonals.
It has been designed in steel for two reasons: during construction, the deck works mainly in tension and the use of steel makes it possible to minimize weight, which becomes important during cantilever construction and reduces seismic effects in service state.
The arch is formed by two parallel hexagonal sections, linked together by means of diaphragms beneath the spandrel columns. These arches are designed in high‐performance concrete, and have pronounced external chamfers, looking for an appropriate aerodynamic behaviour that will reduce its drag coefficient, mandatory parameter in long‐span bridges. These improvements become essential in such a large-span structure.