Technical Guidance Note (Level 1, No. 3): Derivation of imposed loads

This Technical Guidance Note concerns the derivation of wind load onto structures. It is based on Eurocode 1: Actions on Structures Part 1-4; General Actions – Wind Actions. With this being focused on a load that is sensitive to the environment, the UK Annex to the Eurocode plays a significant part as it makes reference to wind speeds that are unique to the British Isles. There are a large amount of variations and conditions the designer must be aware of when determining wind loads on structures. It is for this reason that the reader is referred to the code text more often than in other notes in this series.

This Technical Guidance Note concerns lateral loads that are applied to barriers and wheel axle loads from vehicles. Barrier loading is dealt with slightly differently to other forms of imposed loading. The nature of the loading can vary from people leaning against barriers to vehicles colliding with them at speed. Axle loading from vehicles has to be treated somewhat differently to other forms of imposed loading. While it is possible to assume a blanket area load to represent them, it is the point load from each wheel that needs closer attention.

This Technical Guidance Note concerns the concept of notional loading, which the Eurocodes classifies as Equivalent Horizontal Forces. These are loads that exist due to inaccuracies and imperfections introduced into the structure during its construction. The following text explains how notional lateral loads are incorporated into the design process. (This article was updated in October 2016 to reflect errata issued since its original publication.)