Steel Buildings in Europe

Part 3: Actions 3 - 17 For locations where exceptional snow loads on the ground can occur, they may be determined by: s Ad = C esl s k where: s Ad is the design value of exceptional snow load on the ground for the given location C esl is the coefficient for exceptional snow loads (the recommended value is = 2,0) s k is the characteristic value of snow load on the ground for the given location. The National Annex may recommend another value of C esl , or the design value of exceptional snow load on the ground s Ad . 7.2.2 Snow load on roofs The load acts vertically and refers to a horizontal projection of the roof area. Snow can be deposited on a roof in many different patterns. Two primary load arrangements shall be taken into account:  Undrifted snow load on roofs  Drifted snow load on roofs. Snow loads on roofs are derived from the snow loads on the ground, multiplying by appropriate conversion factors (shape, exposure and thermal coefficients). They shall be determined as follows:  Persistent (conditions of normal use)/transient (temporary conditions) design situations: s =  i C e C t s k  Accidental (exceptional conditions) design situations where exceptional snow load is the accidental action: s =  i C e C t s Ad  Accidental design situations where the accidental action is the exceptional drift and where EN 1991-1-3 Annex B applies: s =  i s k where:  i is the snow shape coefficient. It depends on the angle of pitch of roof  (Table 6.1) C e is the exposure coefficient ( C e = 1,0 is the default value) C t is the thermal coefficient ( C t ≤ 1; C t = 1,0 is the default value). The National Annex may give the conditions of use for C e and C t .