version 0.0.2
September 22, 2017

Snow Drift Loading Lower Adjacent Roofs

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Snow Drift Loading Lower Adjacent Roofs

version 0.0.2
September 22, 2017

Climatic Data

Location
Province:
Ground snow load
Ss:
Rain Load
Sr:
Density
Snow density, γ:
kN/m3

Factors

Importance factor
Is:
Factors
Lower Roof, Cb:
Cw:
snow drift distribution

Upper Roof geometry

Roof Plan dimensions
Longer dimension, l:
m
Shorter dimension, w:
m
Height of parapet, hp:
m

Lower Roof geometry

Roof step, h:
m
Pitch:
/12
Slippery:
Thinking...

Specified Snow Load

[4.1.6.2]
S = Is[Ss(CbCwCsCa)+Sr]

Factors

User input values:
Ss = 1
Sr = 1
Importance Factors
ULS: Is = 1.0
SLS: Is = 0.9
Roof slope = 0 degrees
Slope Factor
For non-slippery roof:
Slope <= 30 degrees.
Cs = 1
Cb = 0.8
Density = γ = 3 kN/m3
[Structural
Commentaries
Fig G-5]

Drift Factors & Distribution

shorter roof dimension, w = 1
longer roof dimension, l = 1 m
Characteristic roof length: lc = 2w-w2/l = 1m
Factor F = greater of:
a) F = 2
b) F = 0.35(γ*lc/Ss-6(γ*hp/Ss)2)0.5+Cb = 1.41

F = 2


Ca(0) = lesser of:
a) Ca(0) = (γ*h)/(CbSs)= 3.75
b) Ca(0) = F/Cb = 2.5

Ca(0) = 2.5


xd = lesser of:
a) xd = 5(h-CbSs/γ = 3.667 m
b) xd = 5(Ss/γ)(F-Cb) = 2 m

xd = 2 m


h' = h - CbCwSs/γ = 0.733m
Min dist where (Cw = 1.0) = 10*h' = 7.333 m

Snow Load Summary

x = 0

Cw = 1
Ca(0) = 2.5

SULS = 1.0[1(0.8*1*1*2.5)+1] = 3 kPa

SSLS = 0.9[1(0.8*1*1*2.5)+1] = 2.7 kPa

0 < x &le ( xd = 2m )

Cw = 1
Ca(x) decreases linearly over 0 < x &le xd
Ca(x) = 2.5 - 0.75 * x (x in meters)

x = xd = 2m

Cw = 1
Ca(xd) = 1

SULS = 1.0[1(0.8*1*1*1)+1] = 1.8 kPa

SULS = 0.9[1(0.8*1*1*1)+1] = 1.62 kPa

x > ( xd = 2m )

Cw = 1.0
Ca(x) = 1

SULS = 1.0[1(0.8*1.0*1*1)+1] = 1.8 kPa

SSLS = 0.9[1(0.8*1.0*1*1)+1] = 1.62 kPa

By using Jabacus or information derived from this Service, you have agreed to the Terms of Service.

This information must be read or used in conjunction with Part 4 and the Structural Commentaries of the NBCC 2005. In the event of discrepancies, Part 4 and the Structural Commentaries of the NBCC 2005 shall govern.

By using Jabacus or information derived from this Service, you have agreed to the Terms of Service.

This information must be read or used in conjunction with Part 4 and the Structural Commentaries of the NBCC 2005. In the event of discrepancies, Part 4 and the Structural Commentaries of the NBCC 2005 shall govern.


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