Timber bridges in Sweden - On-going research and steadily expanding market

In this paper, research on timber bridges both in the past in Scandinavia and on-going in Sweden is summarised. The on-going, more recent research at Chalmers University of Technology focuses on improving our understanding of the mechanical behaviour of stress-laminated-timber (SLT) decks loaded until failure. The experimental results from three full-scale tests on SLT decks are reported. All the SLT decks were made of glulam laminations. Developments in terms of strengthening the anchorage zone where the tension in the pre-stressed bars is applied are leading to a reduction in the structural efficiency of decks. Some results of laboratory tests conducted on SLT decks reinforced in the anchorage zones by means of self-tapping screws are presented. The loss of tension in the pre-stressed bars has been recorded both instantaneously and after a few months in a climate chamber where they were exposed to moisture variation. The schedule for the on-going field studies is presented. Two case-study bridges completed in 2011 are also reported as examples of innovative solutions when it comes to the industrialised production and assembly of very large sections as examples of more spectacular projects performed in Sweden