FIB prize for Yavuz Sultan Selim bridge
The Yavuz Sultan Selim Bridge (3rd Bosphorus Bridge) has been awarded FIB Outstanding Concrete Structure Exceptional Recognition presented at the 2018 FIB congress in Melbourne, Autralia.
The so-called "High rigidity suspension bridge" is breaking the world record for combined road/railway bridges and for railway bridges with its 1'408 m of central span. It is the first modern application of a combination between a classical suspension bridge and a cable-stayed bridge.
ln addition to the natural elegance given by the conceptual design, special attention has been given to developing a dynamic and elegant shape for the towers avoiding any intermediate crossbeam on their height. The triangular-shaped and inclined legs procure a stable and strong feeling despite their slenderness. They give a dynamic and elegant impulse towards the crossing.
The foundations, piers, towers and side span up to 24 m apart from the tower axis in the main span are made of concrete, mainly C60. The main span is a full orthotropic deck with a steel box girder. Most of the structural steel quality is grade S460. Main cables are PPWS with 5.4 mm wires in grade 1'860 Mpa. They are
protected by a dehumidification system. Hangers are PWS with dia 7 mm zinc coated wires in grade 1770 Mpa, protected by a polyethylene sheathing.
Due to their exceptional length (more than 600 m for the longest), stiffening cables are standard PSS with dia 15.7 mm strands in grade 1'960 Mpa to limit the self-weight of the stays and their consecutive sag.
The inclinations of the legs have been fixed to accommodate the vertical plan of the main cables between the roadway and the railway, placing the hangers in the central zone. This allows for a completely free lateral view for the car users on ail the central suspended part, which turns the crossing of the bridge into a dramatic experience.
By anchoring the stiffening cable laterally in the main span and between the railway and the roadway on the back span, it highlights the crossing of the main span and gives the users an unobstructed view of the great scenery provided by the steep-sided Bosphorus and the business city of Istanbul in the background. The extraordinary morning or evening natural light on site plays with the effect brought by the progressive stiffening cable line geometries along the bridge like fingers on a harp.
As a result of this conceptual design, the bridge offers an elegant and top class crossing to the straight, which perfectly symbolises the link between the two continents and could become one of the major landmarks of the extraordinary city of Istanbul. All the constitutive materials have been chosen for their best use, taking into account the local practices and procurement possibilities and the special geographical situation of the bridge in a sensible seismic area and in a maritime environment.