**3. Codes of practice**

Due to the importance of the assessment of the response of bridges to the action of wind, codes of practice have been developed to aid the bridge engineer in the design calculations. They provide definitions, establish best practices, and give recommendations.

Most countries and regions of the world have their own codes of practice for bridge design, for example: "EN 1991, Eurocode 1: Actions on Structures" [8] in Europe; the "Specifications for Highway Bridges" by the Japan Road Association [30] or the "Design Standards of Superstructures for Long-Span Bridges" by the Honshu-Shikoku Bridge Authority [31], in Japan; the "LRFD Bridge Design Specifications" by the American Association of State Highway and Transportation Officials [32] in the USA; the "Wind-Resistant Design Specification for Highway Bridges" [33], in China; the "CAN/CSA-S6-00, Canadian Highway Bridge Design Code" [34], in Canada; and the Australian standard "AS 5100" [35], in Australia.

In the European Union, the named Eurocodes ultimately replaced the several National Codes, with differing rules, in the various Member States. It is worth mentioning the recommendations of the European Convention for Constructional Steelwork (ECCS) [13] or, in the case of the UK up to 2010, the British standard "BS 5400" [36].

Wind actions on bridges are covered in Section 8 of the Eurocode 1 Part 1–4. It is worth pointing out that the code does not apply to bridges involving civil engineering works with heights above 200 m or bridges having spans greater than 200 m. The Vila-Real Bridge to be discussed in Section 8 exceeds both these criteria.

Codes of practice tend to be conservative though, encouraging wind tunnel tests to address the susceptibility to undesirable aerodynamic phenomena, of long-span bridges and/or with atypical shape. In their numerical studies, Bruno and Mancini [20] found for decks with complex geometries errors up to 200% between the simulated forces and the predictions using standard rules (ENV 1991-2-4). Therefore, when it is difficult to fit up a bridge within the regulation in effect, it is unavoidable to resort to aerodynamic experimental studies to obtain design criteria that warrant structural safety and, in many cases, a reduction of the overall cost of the project.
