First infused Japanese bridge

For decades GRP Constructions, Inc in Japan has designed and built hardwood (mostly pedestrian) bridges on the Japanese market. In addition GRPC built several composite bridges based on pultrusion elements. Looking for alternative designs and production processes which do not have the geometrical and structural limitations associated with pultrusions, GRPC came in contact with the Netherlands based company Infra Composites B.V.

Infra Composites has designed and built full composite bridges in the Netherlands, all based on the vacuum infusion process and a structural boxbeam concept. In this concept glass/polyester parts (two sides, one or more girders, deck and bottom shells and bulkheads) are infused and assembled using an adhesive. The concept has proven to be efficient and flexible in terms of easy change of geometries and change between pedestrian and vehicle loads.

Two years ago a co-operation was created between GRPC and Infra Composites in which knowledge about the design and production was transferred to Japanese engineers. Last year a full-scale segment of a vacuum infusion bridge was produced in the Infra Composites production facility during a two-week session in which GRPC workers were trained. In parallel various smaller test articles were produced like bridge deck samples and parapet attachment sections.

A few weeks later a complete bridge was produced in a new dedicated production facility of GRPC in Japan under the supervision of an Infra Composites project manager. This bridge was used for extensive mechanical testing and for promotional activities, while the employees were further trained during the production.

The boxbeam design for the Japanese market could be kept identical to the original design, with two exceptions due to local challenges. Firstly, the occurrence of an aggressive type of fungus in certain districts in Japan prohibited the use of balsa wood as a core in the sandwich deck. Fibre reinforced polyurethane cores were used alternatively. For higher loaded traffic bridges, a multiweb type of bridge deck design will be employed. Secondly, the supports for the bridges also needed to keep the bridges in place in typhoon season while still allowing for thermal expansion.

This year GRPC sold and produced its first vacuum infused boxbeam bridge and installed it in Nagano-ryokuchi in Fukuoka, Japan, and more will follow shortly.

More information:www.grpc.jp – www.infracomposites.com