Stovner Tower – accessible pedestrian walkway

Abstract

ABSTRACTThe Stovner Tower forms part of an activity park in the Stovner district of Oslo. The tower, providing a serpentine walkway through the tree tops with a maximum height of 15m, is designed to be universally accessible. The route is based on a series of straight lengths connected with abrupt changes of direction based on a turning radius of 4m or 7.5m. The 2m wide walkway has an overall length of 270m with a constant 1:15 slope. There are four intermediate horizontal platforms intended as relaxation and viewing areas. Each platform is of variable size with minimum and maximum dimensions of 5.1m and 7.1m respectively. The principal deck structure is steel, formed from a central tube with a diameter of 750mm. The tube is made up of a series of 2m long segments which are faceted as the walkway changes direction. Steel cantilever ribs are located at 1.5m centres to support both the solid timber decking and the 1.3m high guardrail. The central steel tube is supported at multiple locations by tripod columns formed from three glulam timber sections. The GL32c glulam columns vary in size from 200×200mm to 350×350mm depending on their height. The timber columns are anchored directly to the bedrock located close to the surface in this area. Steel walkway sections were shop welded in transportable lengths with bolted connections for on site. Timber to steel connections are also bolted. Steel is painted for corrosion protection. All timber, both solid C24 for decking and glulam columns, is treated for external use. A 3D SAP2000 FE model was used for verifications including a buckling analysis for the slender timber columns and a modal analysis to check for frequencies that would make the structure susceptible to pedestrian‐induced vibrations.