FRP lift bridge over the Oud Rijn: engineering slenderness

In a design contest, RHDHV architect Joris Smits entered a challenging asymmetric design for a lift bridge for the Oude Rijn, Katwijk, the Netherlands. Using the lightweight stiffness of Fiber Reinforced Polymers (FRP) for the deck structure, he created an extremely thin structure, for its beauty and to reduce the number of openings of the bridge by increasing the height of the vertical clearance. The client was thrilled by the design but hesitant to believe the concept was feasible: such complex shape and slenderness. Royal HaskoningDHV was asked to further develop the design and demonstrate the technical and economic feasibility of the design. Could such long slender deck really be achieved? How would it respond to its single lifting arm? This paper discusses the challenges of the asymmetric design of the bridge and explains the FRP engineering solution. Dutch Design Recommendation CUR96 [1] has been used for the structural design.