Deflections should always be considered in the design of slabs, in order to meet serviceability criteria applicable to concrete floor systems. While there are several ways to determine and calculate slab deflections, Tekla Structural Designer is arguably the most capable software solution available.
Kenny Arnott, Principal Structural Consultant at Trimble Solutions (UK) Ltd explains why.
There can be many requirements to consider when assessing deflections of concrete floors: the deflection (slope) of a slab should not be noticeable by occupants and deflections should not cause damage to attached partitions, cladding and other critical non-structural elements. The most basic requirements are stipulated in design codes, but quite often more onerous project specific limits will apply.
‘Flat slabs’ (concrete slabs supported directly by columns/walls without the stiffening effect of beams) offer the greatest concern and challenges in this area. Although buildings have been constructed using flat slabs and columns for many years, serviceability compliance (deflections) was traditionally assessed by hand, without the aid of computers. However, this traditional method relied heavily on regularity, standard conditions and limits to keep design complexity to a minimum. As structures became more individual - and complex - more innovative solutions were required to perform the necessary analysis.
Therefore, a growing choice of specialist slab design software became available to help engineers analyse and calculate deflections more easily. Despite this being good news for engineers, it did mean that a variety of different software solutions would have to be purchased to fulfil these requirements. This in turn meant engineers could end up creating separate analysis/design models in multiple software packages for one project. Any changes, such as column size/position adjustments, would need to be separately applied to keep them in sync with the project’s master model. Indeed, as you can imagine, this could become a very time-consuming and potentially error prone task.
