User documentation
This calculation is presented in three layouts – Full, Standard and Brief
Dialogue
National annex selector
Combobox "National Annex" is used for selecting proper annex for calculation of the snow load.
Snow load requires selecion the national annex, because in Standard EN are not defined characteristic values of snow load on the ground.
For explanation of the National annex parameters related to snow load select national annex from the list below.
General properties
General properties are similar to all snow load forms.
Checkbox "Print headline" represent official name for calculation. User can change it by uncheck "Print headline" and check "Print userdefined headline" and write his own headline into appropriate string line.
Checkbox "Print the dimensions of the construction" show/hide block with Dimensions of the construction
Checkbox "Print the calculation of the load at unit lenght of the roof" show/hide calculation of the Load at unit length in the direction of roof
Checkbox "Undrifted snow" show/hide the calculation of undrifted load case (i)
Checkbox "Drifted snow" show/hide the calculation of drifted load case (ii)
Checkbox "Use calculation according Annex B3" is availabile if national annex allows its use.
Geometry of the roof
Slope of the higher roof is in degrees. Limits are from 0 to 90 °.
Width of the higher building is in meters. Limits are from 0 to 100 m.
Width from the ridge of a roof to the edge of the higher building is in meters. Limits are from 0 to 100 m.
Length of the lower building is in meters. Limits are from 0 to 100 m.
Height of the higher eaves from the lower ridge is in meters. Limits are from 0 to 100 m.
Parameters of the snow load
These parameters are depended on selected National annex.
Exposure coefficient
These parameters are depended on selected National annex.
Thermal coefficient
These parameters are depended on selected National annex.
Calculation
Dimensions of the construction
Values in this block are defined in the dialog. This block can be hidden by checkbox "Print the geometry of the roof".
Characteristic value of snow load on the ground and Coefficients
These parts of calculation are described in the annotation for Coefficients for the snow load
Minimal and maximal parameters of the snow load
These values depend on selected national annex.
Standard values:
μw,min = 0,8
μw,max = 4
ls,max = 5 m
ls,max = 15 m
Dimensions of the construction
Slope of the higher roof is in degress with limits from 0° to 90°.
Width of the higher building is in meters with limits from 0 to 200 m.
Width from the ridge of a roof to the edge of the higher building is in meters with limits from 0 to 200 m.
Length of the lower building is in meters with limits from 0 to 200 m.
Height of the higher eaves from the lower ridge is in meters with limits from 0 to 200 m.
Width of the lower roof loaded by snow is calculated
2*h ≤ ls,min ⇒ ls = ls,min
2*h ≤ ls,max ⇒ ls = 2*h
2*h ≥ ls,max ⇒ ls = ls,max
ls have to be between 5 and 15 meters. These values depend on selected national annex.
Calculation of the snow load
If Calculation according Annex B3 is used, more details about this calcualtion can be found on National annex page.
Two ways of calculation are possible. First when ls ≤ b2, second if ls ≥ b2.
Drifted and undrifted cases are calculated.
Shape coefficient μ1 = 0,8
Coefficient of the sliding snow from the higher roof is calculated
α ≤ 15° ⇒ μs = 0,0
α ≥ 15° ⇒ μs = 0,8*(b1,s/ls)
Coefficient of drifted snow μw = (b1 + b2)/2h ≤ γh/sk
Drifted snow coefficient μw have to be between 0,8 and 4. These values depend on selected national annex.
Weight density of snow can be defined in National annex, standard value γ = 2 kN/m3
Explanation of symbols
b1 - Width of the higher construction [m]
b2 - Width of the lower construction [m]
h - Height of the higher eaves from the lower ridge [m]
ls - Drift length [m]
lmax - Maximal drift length [m]
lmin - Minimal drift length [m]
sk - Characteristic value of snow load on the ground [kN/m2]
γ - Weight density of snow [kN/m3]
μs - Snow load shape coefficient due to sliding of snow from the upper roof
μw - Snow load shape coefficient due to wind
μw,max - Maximal snow load shape coefficient due to wind
μw,min - Minimal snow load shape coefficient due to wind