The Grenland bridge consists of a single pylon cable stayed bridge across the Frier fjord. With a ship channel of 50 x 100m, a back-span area of approximately 67m on the north side, and an approach viaduct of total length 236m on the south side. The 305m main span of the cable-stayed bridge is designed with a steel/LWA concrete composite deck structure. The rest of the deck is designed with a ND concrete slab in composite with the steel box. The pylon is H-shaped with a top elevation of +166m. Most of the back stays are anchored directly to the solid rock via a steel transition structure and rock anchors to an accessible cavern on each side of the road.
Why Expanded Clay:
The bridge design was the winning proposal in an architectural competition. It was the most elegant bridge in harmony with the dramatic bridge site. However, it was clearly recognised that a design with two pylons would have given a more economic design. For the single pylon bridge the anchorage of the back stays in the existing steep rock face in combination with the rock tunnel entrance is a major visual and structural element.
The design of the main span with a steel box in composite with a LWA-concrete LC 55 slab and edge beams was found to give the minimum cost. The slab itself was designed with LWA elements, thickness 130mm, and a composite cast-in-place LWA-concrete LC 55 topping, t = 120mm min. Composite action with the steel box was provided by welded studs in the joints. An expansion joint was provided in the main span 14.0 m from axis 3.