ETL 1110-2-534
30 Sep 94
A-3. Example Problem
fallow = 97 MPa
(2) From Table A-2, the section properties for
a. Problem definition. The guardrail in
the post are:
Figure A-4 has 10 spans and has a change of direc-
tion at both ends. Both the toprail and posts are
= 129,000 mm4
I
38-mm, schedule 40 pipe, from 6061 T6 Aluminum.
The posts are spaced at 1.2 m on center and are
= 5,340 mm3
S
welded to a round aluminum plate with a 15 cm
diameter (d = 11.4 cm). The plate is attached to a
(3) Determine the load proportion factor Pf
concrete surface via four symmetrically spaced
based on the relative stiffness R:
10-mm-diam wedge-type concrete anchors. The
manufacturer-specified pullout strength for the
anchors is 18.2 kN per anchor (including the safety
ERail
IyRail
factor). Determine whether the guardrail system
kRail
L
R
can safely withstand the USACE-specified 890-N
kPost
EPost
IPost
(200-lb) horizontal concentrated loading.
h
(69 103 MPa)(129,000 mm 4)(1,040 mm)
(69 103 MPa)(129,000 mm 4)(1,220 m)
0.85
From curve "L" of Figure A-1, Pf = 0.53
(4) Calculate the applied moment:
Mapplied
P
h
Pf
(890 N) (1,040 mm) (0.53)
491,000 N
mm
(5) Compare applied stress to allowable stress:
Mapplied
491,000 N mm
fapplied
5,340 mm 3
S
97 MPa) ⇒ Good
92 MPa < (fallow
Figure A-4. Railing for example problem
b. Existing condition. Prior to any analysis,
the guardrail system should be carefully inspected
d.
Railing analysis.
for deterioration as described in paragraph A-2b.
(1) Calculate the applied moment:
For this example, it will be assumed that the guard-
rail system is in good condition and thus no reduc-
tions will be made to the allowable stresses or
P
L
(890 N)(1,220 mm)
Mapplied
section properties.
5
5
217,000 N
mm
c.
Post analysis.
(1) From Table A-1, the allowable stress for
Aluminum 6061 T6 pipe within 25 mm (1 in.) of a
weld (Refer to footnote in Table A-1) is:
A-8
Previous Page
