Civil Engineering Reference
In-Depth Information
Figure G12-2
(
Continued
).
which results in a total load (balanced plus surcharge) of 35.1 lb/ft
2
. The
horizontal extent of the gable roof drift on the storage building is
8
3
hS
=
8
3
273
(.
ft) 12
=
252
.
ft
d
Roof Step Drifts
The heated storage building is also subject to leeward roof step drifting due
to wind from the west and windward roof step drifting due to wind from the
east. For the leeward drift, the upwind fetch distance, C
u
, is 100 ft. Hence, the
height of the leeward drift is
l
−
3
−
h
d
=
0.43
3
p
g
+
10
1.5
=
0.43 100
30
+
10
1.5
=
3.51 ft
4
4
u
For the windward drift, the upwind fetch C
u
=
150 ft. Therefore, the height
of the windward drift is
h
d
=
0.75 0.43
p
g
+
10
1.5
=
0.75 0.43 150
3
30
+
10
1.5
=
3.18 ft
3
4
4
u
