Curved footbridges supported by a shell obtained as an envelope of thrust-lines

Since Maillart’s curved arch bridges in concrete, different typologies of curved bridges in both steel and concrete have been constructed. On the contrary, since Musmeci’s shell supported bridge in Potenza, few shell bridges have been designed. This paper show how to design a curved shell supported footbridge shaping the shell by using the Thrust Network Analysis. As a matter of fact, a shell supported footbridge is shaped between two curved arches, the one supporting the deck and with assighed layout depending on the layout of the road, and the one that defines the shell boundary at the lower part of the shell, the latter being found as a thrust line in the three-dimensional space. The influence of the boundary conditions on the bridge shape obtained as an envelope of thrust-lines is also investigated.