ISO 4355:2013 pdf download.Bases for design of structures -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 in national standards, 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 in formation 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 this International Standard.
Specification of standard procedures and instrumentation for measurements is not dealt with in ISO 4355.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 2394, General principles on reliability for structures
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
characteristic value of snow load on the ground
load with a specified annual exceedance probability
Note 1 to entry: It is expressed in kilonewton per square metre (kN/m2).
Note 2 to entry: In meteorology, the term “weight of the ground snow cover” is also used.
3.2
shape coefficient
coefficient which defines the amount and distribution of the snow load on the roof over a cross section of the building complex and primarily depends on the geometrical properties of the roof
3.3
value of snow load on roofs
function of the characteristic snow load on the ground,and appropriate shape coefficients
Note 1 to entry: The value of s is also dependent on the exposure of the roof and the thermal conditions of the building.ISO 4355 pdf download.