ISO 4355:2013 pdf free

ISO 4355:2013 pdf free.Bases for design of structures一Determination of snow loads on roofs
ISO 4355 specifies methods for the determination of snow load on roofs.
It can serve as a basis for the development of national codes for the determination of snow load on roofs.
National codes should supply statistical data of the snow load on ground in the form of zone maps, tables, or formulae.
The shape coefficients presented in this International Standard are prepared for design application, and can thus be directly adopted for use in national codes, unless justification for other values is available.
For determining the snow loads on roofs of unusual shapes or shapes not covered by this International Standard or ISO 4355, it is advised that special studies be undertaken. These can include testing of scale models in a wind tunnel or water flume, especially equipped for reproducing accumulation phenomena, and should include methods of accounting for the local meteorological statistics. Examples of numerical methods, scale model studies, and accompanying statistical analysis methods are described in Annex G.
The annexes describing methods for determining the characteristic snow load on the ground, exposure coefficient, thermal coefficient, and loads on snow fences are for information only as a consequence of the limited amount of documentation and available scientific results.
In some regions, single winters with unusual weather conditions can cause severe load conditions not taken into account by ISO 4355.
Specification of standard procedures and instrumentation for measurements is not dealt with in ISO 4355.
Roofs shall be designed to preclude ponding instability. For flat roofs (or with a small slope), roof deflections caused by snow loads shall be investigated when determining the likelihood of ponding instability from rain-on-snow or from snow meltwater.
The characteristic snow load on the ground, so, is determined by statistical treatment of snow data.
Snow load measurements on the ground should be taken in an undisturbed area not subject to localized drifting.
Methods for the determination of the characteristic snow load on the ground, So, are described in Annex A.
For practical application, the characteristic snow load on the ground will be defined in standard step values, which will yield basic values for the preparation of zone maps as described in Annex A.ISO 4355 pdf download.