Technical Guidance Note Level 3, No. 2: Axial shortening

This Technical Guidance Note concerns the concept of axial shortening – a phenomenon that occurs in vertical loadbearing elements within all structures, but whose effects are especially pronounced in those over 15–20 storeys high. Reinforced concrete frames are most prone to axial shortening due to the impact of shrinkage and creep on composite materials. This note covers the causes of axial shortening, how it is assessed and predicted, and the mitigation measures structural engineers and building contractors employ to counter its effects, particularly in relation to fit-out and facade installation following building construction. The note also refers to ways in which current codes of practice offer a means to analyse structures for axial shrinkage.