Wind Forces on Medium-Span Bridges: A Comparison of Eurocode 1 Part 4 and Computational Fluid Dynamics

Abstract

Bridges often have complicated geometries in complex terrain where they can be exposed to high wind loading. Current practice in designing for wind can be conservative. The drive for more lean construction motivates the study of computational modelling as an alternative to traditional methods of determining these wind loads. This paper compares wind forces determined using Eurocode 1 Part 4 with those determined by CFD modelling for a given bridge geometry, taking variations in altitude, location, wind speed and wind direction into account. Results indicate that the exposure factors used in Eurocode 1 Part 4 inflate the net wind force values. It was also found that the directional factor is conservative for wind forces on bridge decks but ineffective for wind forces on bridge piers in the x-direction. Furthermore, the Reynolds-Averaged Navier–Stokes equations (CFD) appear to produce smaller values of net wind force than Bernoulli’s equation (Eurocode). Bernoulli’s equation can only be applied to an ideal fluid, and Reynolds-Averaged Navier–Stokes equations can be applied to any viscous fluid—a further concern with the current practice.

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“…Likewise, for constructing highrise buildings and long-span bridges capable of withstanding wind forces, knowledge of strength and structure is required for simulation rules prior to construction. Wind is an important consideration in structural design, and bridges frequently have complex geometries and are located in complex terrain that can be exposed to high wind loads [6].…”