A new approach to fl oor loading
-
Alastair Hughes [1]
-
[1] MA
-
- Localización: The Structural Engineer: journal of the Institution of Structural Engineer, ISSN 1466-5123, Vol. 99, Nº. 1, 2021, págs. 36-38
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
-
Resumen
For most buildings of more than one storey, the important variable action – the payload, so to speak – is gravity loading imposed on fl oors.
Currently, in the Eurocodes, values for design are derived from the intended occupancy of the space in question, according to a table in EN 1991-1-11 – or strictly speaking its National Annex (NA), because nations do not always see eye to eye.
These assumptions aff ect safety, so EN 1991-1-1, while off ering RVs (Recommended q- and Q-values), has to tolerate a credibilitystretching range of national choice for its 12 categories or subcategories of occupancy. The UK NA2 generates multiple sub-subcategories, each with its own pair of values. The motive may have been to ease the transition from predecessor standards, but the result is complexity and disharmony. In 2021, with fi rstgeneration Eurocodes up for revision, we have an opportunity to do better.
This article explores the idea of categorising the opposite way round: not by occupancy but by loading. Four categories, with q = 2, 3, 4 and 5kPa (kN/m2 if preferred), will cover most normal building fl oors. As now, each of these equivalent uniformly distributed loads is partnered by an alternative singly applied roving point load, Q, of 2, 4, 4 and 5kN respectively (with one outlier: car parking fl oors at 10kN, to allow for a wheel change).
Instead of quoting two values (in kPa and kN) for every variant of occupancy, the table can simply list the occupancies that each category is good for. This new approach is not revolutionary in any other sense. There is no intention to overturn the traditional loadings or their modus operandi. It does, nevertheless, provide opportunities to tidy up, to refresh and to promote borderless structural safety.
