Searching for new architectural forms of steel arch footbridges

Nowadays, in Poland as well as in the whole world many footbridges over motorways or ring roads of cities are being constructed to improve the safety of pedestrians. An important issue becomes the architectural diversification of neighbouring structures. In the paper a project of an unusual steel structure of an arch footbridge over motorway with span exceeding 50 m is presented. A specific solution for hangers is proposed where originally shaped 8 mm thick steel shells are applied. For this kind of structure numerical analysis by means of two types of Finite Element models is performed and its selected results are presented and discussed. To represent the geometrical nonlinearity in the behaviour of a thin shell subject to transverse loads the application of an advanced FE model of the hanger taking into account large deformation theory is indispensable. A special attention is paid to fatigue analysis of the shell hanger subject to lateral wind action. The results of analyses confirm that the steel shell may be quite freely shaped to achieve the architectural purpose. In the paper various possibilities of shaping the steel shell are also shown. The proposed solution seems to be relatively attractive and at the same time to be cheaper than structures with traditional hangers made of steel wire ropes or rods.