Numerical study of wind loads on the streamlined bridge deck in the translating tornado-like vortex

Abstract

Wind load is one of the key factors affecting the structural safety of long-span bridges. However, the tornado-induced load on the streamlined bridge deck is rarely studied and the influence of the translation of tornado vortices has not been considered. This study develops a computational fluid dynamics (CFD) method to simulate the translating tornado-like vortex (TLV) to investigate the tornado-induced load on the streamlined bridge deck. First, the numerical method for simulating a translating TLV is introduced and the model of the streamlined bridge deck of a kilometer-level bridge is constructed and verified. The characteristics of the flow field around the bridge deck are then analyzed. Finally, the lift force, drag force, and torsional force on the bridge deck in the translating TLV are investigated and compared with those in the straight-line wind field and the stationary TLV. The non-dimensional forces obtained in the translating TLV are provided as a reference for calculating the tornado-induced load on a streamlined bridge deck. The result shows that the wind load on the bridge deck in the TLV changes along the spanwise direction, which is significantly different from that in the straight-line wind field. In the translating TLV, the bridge deck sustains the lift force induced by the updraft and the drag force induced by the translating velocity. The load on the bridge deck in the translating TLV is significantly larger than that in the straight-line wind and the stationary TLV, which indicates that the translation effects of tornadoes should not be ignored.