Technical Guidance Note (Level 1, No. 4): Derivation of wind load

Imposed load is defined as the load that is applied to the structure that is not permanent and can be variable. In Eurocode phraseology, it is described as a 'quasi-permanent variable action'. Please be aware that this note does not cover lateral loads onto barriers, balustrades and axle loads from vehicles. These will be covered in a forthcoming note. (This article was updated in October 2016 to reflect errata issued since its original publication.)

While the advancement of computer based analysis continues to grow exponentially within the field of structural engineering, the tools that are used to analyse structures by hand are no less relevant. Many would argue that such tools are even more vital today than they have ever been if we are to fully understand the output of analysis applications. With this in mind, this Technical Guidance Note describes one of the most powerful analysis tools available: moment distribution. Moment distribution is a method by which statically indeterminate structures are analysed elastically. It’s based on the relative stiffness of elements that make up a structure and shifts bending moments from one section of the structure to another until they become balanced. Once this balance has been achieved, the forces and bending moments within the structure are modelled. (This article was updated in October 2016 to reflect errata issued since its original publication.)

This Technical Guidance Note describes the concept of biaxial bending of columns, as well as the effect direct bending has on column design. The guidance given here can be applied to columns made from any material, be it steel, concrete, timber or even glass.