Technical Guidance Note (Level 1, No. 10): Principles of lateral stability

Once the concept and scheme for a structure has been settled upon, the initial sizing of the elements that it is made up of commences. This Technical Guidance Note provides a set of hints as to how to initially size elements, prior to carrying out the detailed design. This process allows the engineer to gain an appreciation of the form of the structure and the changes that may be required if element sizes prove to be too onerous following this size estimation process. Access more Technical Guidance Notes through our series homepage .

This Technical Guidance Note is an introduction to the assessment of floor vibrations. Since the adventof lighter structures that have longer spanning elements within them, the built in dampening effectbuildings have had historically has become less pronounced. Despite this, floor vibration canbe an overlooked criterion during the design process. This can lead to expensive remedial works being carried out on structures after they have been built, as occupants complain of discomfort due to excessive movements and vibrations. (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.)