Vehicle Collision into Steel Pedestrian Bridges

During 2010 a few steel footbridges collapsed in Finland as a result of over-height vehicles collid-ing into the superstructure. This caused an investigation into horizontal impact loads on superstruc-tures of pedestrian bridges and the magnitude of the collision force. To analyze the collision numer-ically, many parameters must be taken into account and a dynamic structural analysis must be per-formed. The magnitude of impact is strongly affected by the mass distributions and rigidities of the colliding vehicle and the bridge during the collision, as well as vehicle velocity, damping, changes in the geometry of both objects, the nature of the contact surface and resulting energy losses etc. The duration of collision time is short, usually only fraction of seconds, causing difficulties in the numerical analysis. In this paper a vehicle collision on bridge deck is reported. Collision forces of design codes are compared to the values obtained by simple spring mass system and results ob-tained by using dynamic nonlinear finite element analysis.