Edinburgh Napier University

  This paper describes the experimental part of a research programme carried out at Napier University in collaboration with the UK's Forestry Civil Engineering, Forestry Commission, to develop a series of new laminated modular systems for timber bridges. It details some of the practical/construction issues relating to their off-site manufacture and on-site assembly. The work follows on from recent research studies by the authors on developing vertically stress laminated timber arches. It is focused on using stress lamination technique to utilise the UK grown small-sections of low-grade timber to form strong low cost sustainable bridges. The main advantages of this form of lamination are the lateral distribution of load, the dispersement of defects in the timbers and the use of timber in compression. The very low cost of early arch bridges was offset by the expensive installation/ erection costs; so ways of reducing these costs have been the focus of current work. For large span bridges, modular construction was considered an effective way of reducing scaffolding costs; whereas, for the short-span ones, complete manufacture of bridges in the workshop was regarded as the best way of reducing site costs. The use of nailing, screwing and gluing was also examined to facilitate the modular construction, to improve stiffness and strength and to reduce cost of stressing.