The Rollout Stress Ribbon Bridge

THE ROLLOUT STRESS RIBBON BRIDGE Stress ribbon bridges are light and visually elegant. At sites with solid conditions for tension based anchoring, they can also be very economical. This paper presents the concept of a roll-out stress ribbon bridge where the load-carrying element is a plane deck plate. By the principle of rolling the entire bridge deck to a coil at a steel-mill or workshop and un-coiling on site, stress ribbon footbridges can be built with minimal construction on site. The coiled bridge-deck can easily be transported on one truck and the construction can be done without heavy vehicle access to both ends of the bridge. This paper suggests how to launch this type of bridge and discusses some basic material as well as structural properties regarding static and dynamic performance. Similarly to stress ribbon bridges in general, basic design criteria relate to anchoring the horizontal forces at abutments and to dynamic properties in relation to pedestrians. In addition, the Rollout Bridge has some particular design issues related to the procedure of un-coiling and to pulling the bridge deck over the span. As the bridge deck is heavier than the tension elements in stress ribbon bridges where tension elements and bridge deck are separate, the horizontal forces during construction requires more attention. Briefly analysing some alternatives concerning span length and slope at abutments indicates that the concept is promising and worth further studies in tuning geometry, materials and weights and developing more explicit design of a bridge to be constructed in real.