THE SECTION MODEL
Once the bridge cross-section has been selected, testing of a section model is usually prescribed. A precisely constructed model is placed in the wind tunnel using a dynamically scaled mounting system. The wind conditions of the site are simulated in our state-of-the-art wind tunnel, using both turbulent and smooth flow. This determines the aerodynamic response characteristics of the bridge section and alerts designers to critical wind speeds at which instabilities, such as vortex shedding or flutter, arise. These tests are detailed and thorough in order to provide a sound understanding of the behaviour of the bridge section.
If stability characteristics are not satisfactory, modifications to the aerodynamic cross-section of the section model can easily be made and tested immediately. This is an interactive process with the designer, providing quick and accurate feedback to ensure an optimum design.
Wind tunnel test results from the section model are then combined with the meteorological information for the region in which the bridge is situated. The resulting predictions are placed into a format suitable for the design engineer, namely, Equivalent Static Loads (ESL).