Steel Buildings in Europe

Part 3: Actions 3 - 16 7 SNOW LOADS 7.1 General This document gives guidance to determine the values of loads due to snow to be used for a typical single-storey building according to EN 1991-1-3. The design procedure is summarized in a flowchart (Figure 7.5). A worked example dealing with the determination of the snow loads on a single-storey building is given in Appendix A. The guidance does not apply to sites at altitudes above 1500 m (unless otherwise specified). Snow loads shall be classified as variable, fixed actions, unless otherwise stated in EN 1991-1-3. For particular conditions like exceptional snow loads and/or loads due to exceptional snow drifts, they may be treated as accidental actions depending on geographical locations. Snow loads should be classified as static actions. Two design situations may need to be considered:  Transient/persistent situation should be used for both the undrifted and drifted snow load arrangements for locations where exceptional snow falls and exceptional snow drifts are unlikely to occur.  Accidental design situation should be used for geographical locations where exceptional snow falls and/or exceptional snow drifts are likely to occur. The National Annex may define which design situation to apply. 7.2 Methodology 7.2.1 Snow load on the ground Different climatic conditions will give rise to different design situations. The possibilities are:  Case A: Normal case (non exceptional falls and drifts)  Case B1: Exceptional falls and no exceptional drifts  Case B2: Exceptional drift and no exceptional falls (in accordance with EN 1991-1-3 Annex B)  Case B3: Exceptional falls and exceptional drifts (in accordance with EN 1991-1-3 Annex B) The National Authority may choose the case applicable to particular locations for their own territory. The National Annex specifies the characteristic value s k of snow load on the ground to be used.