Mindestnutzhöhen von Stahlbetonplatten für l/250 und l/500

Minimum useful heights of reinforced concrete for l/250 and l/500

The static useful height and hence the cross-sectional height of reinforced concrete slabs is determined by limiting the component sag. This restriction is necessary in order to prevent damage due to excessive sagging of the floor or in non-constructional walls. It is based on geometrical criteria (permitted flexural slenderness values) without direct calculation. The values stated in DIN 1045-1 [1] and Eurocode 2 [2] are of different magnitudes and do not comply with the limit values of l/250 and l/500 which are likewise stipulated there for the sag. Moreover, despite their distinctly lower stress and strain, slabs with biaxial stress are treated in the same way as slabs with uniaxial stress where flexural slenderness is concerned. To eliminate these differences, a suitable solution is presented for a sag of l/250 and l/500, with equations for useful heights and diagrams which are valid for both rigid and elastic linear support as well as point support in uniaxial and biaxial structural conditions.