Modern Bridge for Modern District: The Marina Bayfront Bridge
The Urban Redevelopment Authority and the Land Transport Authority in Singapore are constructing two new bridges that will link Raffles Avenue to the Marina Bay Sands. The Marina Bay Sands is a new urban development that will include hotels, up market shops, first class restaurants, theaters and a congress center.
The first bridge is a pedestrian bridge featuring a unique double helical design and will undoubtedly become a new landmark for Singapore. The second bridge, a 6-lane dual carriageway bridge, is also an elegant structure that runs parallel to the curved pedestrian bridge. The bridge features a 19.8m wide triple cell box girder which was cast in-place using DYWIDAG form travelers. Precast wing slabs are attached to both sides of the box girder for the entire bridge width of 38.6m.
DSI’s licensee in Singapore, Utracon Structural Systems Pte Ltd, was an active participant in the planning and construction of the vehicular bridge. Besides supplying and operating the DYWIDAG form travelers for the casting of the cast in-place box girder, Utracon was also involved in the precast wing slab erection and post-tensioning work.
For the in-place casting of the triple cell box girder, 4 DYWIDAG form travelers were used at each end of the cantilever construction. Each 4.0m long segment was cast in a 10 to 14 day construction cycle, with the longer cycle needed for the forming of in-place diaphragms that had to be cast for some of the segments.
One precast wing slab measures 2.4x8.5m and weighs approximately 30t. A hydraulic truck crane was used for placing the wing slabs. Prior to the casting of the 1.6m wide closure pour and permanent post-tensioning, the wing slabs were temporarily tied back using DYWIDAG THREADBAR®.
The box girders are strengthened by DYWIDAG 12x0.6" and 19x0.6" Internal Post-Tensioning Tendons and 19x0.6“ and 27x0.6" External Post-Tensioning Tendons. The installation and stressing of the 10 external tendons was one of the main features of the bridge construction, as the tendons spanned the entire length of the 300m long bridge.
Due to the external tendons’ exceptional length, 2 strand pushers were used for the strand installation process. One pusher was stationed at one end of the tendon, while another pusher was positioned at mid-span. From here, strands were gripped and pushed towards the other end via an opening in the HDPE duct.