Just completed three demonstration demountable bridges for the University of Manchester, School of Engineering. With structural engineering by Arups. The three bridge types where :box beam, with some options, an Arch and a Truss. All three where designed within very fine engineering tolerances -with some potential failure of elements and are aimed at showing detailed structural principles to the students. The box beam was simple to make, and strong. The arch has 21 separate birch ply arch blocks with the option of a tension strap through the the middle. The thrust line was deliberately kept narrow so there was alot of movement within the arch.
The truss was a complex material assembly of Douglas fir, birch ply and stainless steel nodes, connections and tie rods, with lots of repeat elements. Depending upon whether it was set up in tension or compression various elements could be swapped and elastic cord used for the tension elements.
The design and manufacture all three bridges required very close collaboration between the arup engineer and ourselves with lots of modifications and changes along the way and was quite a challenge all round. The truss and the thrust blocks to support all three being the most complicated.
Thanks to Wayne and Steve from Tyree Fabrications for making all the stainless components and to Richard at Cutting Edge Woodworking for the CNC components for the arch blocks.