Technical Guidance Note (Level 1, No. 5): Derivation of snow load

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.)

The twisting of elements within structures due to eccentric loading is something that is best avoided as far as is possible. Such actions develop torsion forces in elements against which they were not designed to withstand. This Technical Guidance Note concerns this buildability and detailing issue that structural engineers must become familiar with in order to avoid otherwise unforeseen problems that can lead to significant remedial works on site and in some cases failures.

This Technical Guidance Note acts as an introduction to the core design concepts that are found within the current codes of practice used within the UK. It also explains the relationship between each of the other guidance notes and how the reader is to navigate and use them. All of the subsequent notes make reference, be they direct or implied to this core guide; it is therefore imperative that anyone seeking to use these guides must be fully conversant with what is contained within this note.