Page
11
SunFrame
Unirac Code-Compliant Installation Manual
R
1411 Broadway Boulevard NE
Albuquerque NM 87102-1545 USA
Step 2a: Determine the
Distributed Load on the rail
based on uplift and downforce, w (plf):
Determine the
Distributed Load, w (plf)
, by multiplying the
module dimension, B (ft), by the
Total Design Load, P (psf)
. Use
the maximum absolute value of the three downforce cases and
the Uplift Case . We assume each module is supported
by one rail .
w = PB
w
= Distributed Load (pounds per linear foot, plf)
B
= Module Dimension Perpendicular to Rails (ft., see Figure 3)
P
= Total Design Pressure (pounds per square foot, psf)
Step 2b: Determine the
Distributed Load on the rail
based on side load, w (plf):
Determine the Distributed Load w (plf), by multiplying the
module width B (ft) by the Total Design Load P (side)
w = PB
w
= Distributed Load (pounds per linear foot, plf)
B
= Module Dimension Perpendicular to Rails (ft)
P
= Total Design Pressure for side load (pounds per square foot, psf)
Step 3: Determine
Rail Span/ L-Foot Spacing:
Using the
distributed load, w
, from
Part II
,
Step 2
, look up the
allowable spans, L
, for SunFrame .
There are two tables,
Table 8a
for uplift and downforce and
Table 8b
for side load . Look up the allowable span for uplift/
downforce from
Table 8a
and side load from
Table 8b
. Span
for the system will be the lower of the 2 appropriate values
from
Tables 8a and 8b
.
Table 7. ASCE 7 ASD Load Combinations
Note: Table to be filled out or attached for evaluation .
Description
Variable
Downforce
Case 1
Downforce
Case 2
Downforce
Case 3
Uplift
Side
Units
Dead Load
D
1.0 x D ______
1.0 x S ______
1.0 x D ______
1.0 x P
net
____
1.0 x D _______
0.75 x S _______
0.75 x P
net
____
0.6 x D _______
1.0 x P
net
______
sin(roof angle) x D
__________
sin(roof angle) x S
__________
psf
Snow Load
S
psf
Design Wind
Load
P
net
psf
Total Design
Load P
P
Sum of above two
numbers ______
Sum of above two
numbers ______
Sum of above 3
numbers ______
Sum above two
numbers* ______
Sum above two
numbers ______
psf
Table 8a. L-Foot SunFrame Series Rail Span (uplift and downforce)
20
25
30
40
50
60
80
100
120
140
160
180
200
220
240
260
280
300
2
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
2.5
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
3
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
3.5
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
4
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
4.5
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
5
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
5.5
SF
SF
SF
SF
SF
SF
SF
SF
SF
SF
6
SF
SF
SF
SF
SF
SF
SF
SF
SF
6.5
SF
SF
SF
SF
SF
SF
SF
SF
7
SF
SF
SF
SF
SF
SF
SF
SF
7.5
SF
SF
SF
SF
SF
SF
SF
SF
8
SF
SF
SF
SF
SF
SF
SF
8.5
SF
SF
SF
SF
SF
SF
SF
9
SF
SF
SF
SF
SF
SF
9.5
SF
SF
SF
SF
SF
SF
10
SF
SF
SF
SF
SF
10.5
SF
SF
SF
SF
11
SF
SF
SF
SF
11.5
SF
SF
SF
12
SF
SF
SF
w = Distributed Load (plf)
Span
(ft)
Table 8a. L-Foot SunFrame Series Rail Span (uplift and downforce)
