Norgesporten road bridge, the gateway to Norway

Abstract

ABSTRACTThe Norgesporten bridge, in the town of Ørje in Norway, provides a landmark on arrival in Norway on the E18 Stockholm‐Oslo highway. The bridge was completed in 2017 for Staten vegvesen, the Norwegian Public Roads Administration (NPRA). The bridge, with two traffic lanes and a pedestrian/cycle path, carries local traffic over the E18. A 75m span cable stayed bridge with a curved steel deck and a 50m high, slender steel pylon asymmetrically located on the outer curve. There are 10 deck cables and five backstay cables connecting the pylon to a concrete counterweight foundation. All cables are ϕ60mm locked coil strand. The main architectural feature of the bridge is the slender, spindle‐shaped pylon, 1.9m maximum diameter, which is restrained in three directions by the cables that cross to create a complex shape and volume. The steel deck is a multi‐cell box girder, 2.1m deep, with cantilever ribs at 6m centres. The orthotropic top plate is stiffened longitudinally with trapezoidal sections. The bridge's complex geometry was analysed using both frame and shell FE models with SAP2000. A full 3D geometric model was used to develop the project drawings and as a basis for the Contractor's own 3D Tekla fabrication model. The bridge has been designed and fabricated in accordance with NPRA Handbooks N400, R410, and R762, with strict requirements for future inspection and maintenance and the box girder is fully accessible and includes dehumidifying plant. The pylon section is designed as inaccessible and airtight. The steel is painted with a duplex system for corrosion protection. The steel deck made up of 25 sections, and the pylon, in three parts, were fabricated in Riga, Latvia before transportation and site welding. During the fabrication process strict controls of the bridge geometry were carried out including partial trial assemblies of the completed sections.