e-mosty March 2019 Long Span and Multiple Span Bridges - Page 11

Figure 9: Ground improvement for tower foundations Wall panels are pre-assembled and lifted into position. They are connected with horizontal block joints, welded skin plates and bolted splice connections of the longitudinal stiffeners. the decks of the approach viaducts at each end. This means that they are set back from the end of the 770m suspension bridge side spans. The suspension cables are formed of PPWS – Prefabricated Parallel Wire Strand – which are continuous between the anchorages. The tie- down, each comprising 4 No. tensioned bars, is clamped to the main cable and transfers load directly to the piled foundation of the side span pier. This method enables fast construction with the possibility to erect further blocks above before finalising welding works. Anchorages and Cables The ground conditions for the anchorages are critical in order to resist the massive forces from the suspension cables. Superstructure The deck of the bridge will be at a maximum height of 72.8m creating a clearance of 70 x 1600 m, and will have a total width of 45.06m and an overall depth of 3.5m. It will carry six lanes (three in each direction), together with a maintenance walkways on each side. There is weak soil on both the European and Asian shorelines, so the side spans were increased to take advantage of founding the anchor blocks within the Miocene rock further from the shore. Like the Osmangazi Bridge, the anchorages are designed to minimise their height so that the tension forces are transmitted directly to the foundation blocks, reducing the over-turning moment. The anchorages are positioned below The bridge deck comprises two stiffened steel box girders spaced 9m apart, connected by 3.5m deep cross-girders every 24m. Figures 10 and 11: Ground conditions – anchor blocks 1/2019