Selfstressed bowstring footbridge in FRP

An original structural concept of footbridge, Taylor-made for fibre reinforced polymer (FRP) is proposed in this work. The bowstring bridge is obtained by elastic buckling of straight pipes (glass fibre). The bows are stabilized with cables and zigzag stays (carbon fibre). Crossbars at the intersection nodes of the cables with the stays support the bridgedeck. The selfstress state in the structure depends on the pipes and on the geometry. A finite element study describes the behavior of such a non-linear structure and highlights its specificities, among which variability in the stresses from one element to the other. A formfinding process based on the method of force density is then developed, to ensure an equal distribution of prestresses in the composite retainers. This method allows the optimization of the design of the structure. Preliminary static and dynamic studies show the structural interest of the concept, and its future is discussed.