Numerical Simulation of Dynamic Wind Load of the Foot-bridge

Pedestrian bridge structures are usually sensitive to the effects of wind due to their relatively high slimness and low weight. The arising forces can excite both oscillation in the direction of the wind and also crosswise torsion-flexure oscillation which can result in a local or (in the case of coupled torsion-flexure oscillation) complete loss of aerodynamic stability of the structure. This study examines, among others, the influence of the parapet on the resultant force affecting the profile of the bridge deck. It is possible to consider partially permeable panels made from perforated metal sheets with the use of a so-called porous medium. However, the evaluation of the force which affects this part of the structure is relatively difficult. For this reason, two ultimate variants were examined: a bridge deck with a perfectly permeable parapet and another with a non-permeable parapet. Transverse oscillations of the cross-section known as a galloping are referenced and a quasi-static approach of its solution is adopted. Basic assumptions for arise of these vibration produced instabilities are named. Key-Words: Dynamics, Foot-bridge, Cycle loading, Vortex shedding, Steel structure