Safety Design Of Lightweight Roofs Exposed To
Snow Load
Author(s)
M. Holický
Abstract
The collapse of a number of lightweight roofs during the winter period of
2005/2006 initiated an international discussion concerning the reliability of roofs
exposed to permanent snow load. In some countries, all available measurements
of snow loads have been newly evaluated and relevant standards have been
promptly revised. Newly developed maps of snow loads are based on the
principles of the European standards specifying the characteristic value of snow
load on the ground as the 98 fractile of annual extremes (50 year return period).
This paper provides a critical analysis of presently accepted design procedures
taking into account available data of snow load. In the reliability analysis
permanent load is described by normal distribution, snow load by Gumbel
distribution and resistance by lognormal distribution. It appears that the partial
factor design method provided in the present European standards may not
guarantee an adequate reliability level of lightweight roofs. An alternative
procedure for the safety design of roofs exposed to self weight and snow load
only is therefore proposed.
Keywords: lightweight roofs, snow load, safety, design.
1 Introduction
The reliability of lightweight roofs has become an important topic of structural
design, particularly after the winter period 2005/2006 when a number of roofs in
Europe collapsed. In some countries, available measurements of snow loads have
been newly evaluated and relevant standards have been promptly revised. Newly
developed maps of snow loads take into account the principles of valid European
standards [1–3] specifying the characteristic value of snow load on the ground as
the 98 fractile of annual extremes. The design value of snow load is then
determined using the partial factor 1,5.
Keywords
lightweight roofs, snow load, safety, design.
Related Book
Other papers in this volume
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