Static Load Tests of Franklin Steel Signpostsby
and Dean L. Sicking
Texas A&M Research Foundation Texas Transportation Institute
Texas A&M University College Station, Texas 77843
Submitted to
December 1981
We are sorry but some of the older reports or AS IS.
The pictures are of poor quality.
FOREWORD
This report presents the results of a series of static load tests of
Franklin Stee 1 Company signposts conducted by the Texas Transportation
Institute (TTl). The work was conducted in accordance with the following
Franklin Steel purchase orders:
F5185 dated May 6, 1980: Initial test program involved static
tests of 2. 5 1 b/ft and 4.0 1 b/ft Eze-Erect systems with 5/16
in., grade 5 splice bolts.
F6286 dated October 9, 1980: This purchase order expanded the
work plan to include static testing of a 4.0 lb/ft Eze-Erect
system with 5/16 in., grade 8 splice bolts.
F6884 dated November 24, 1980: This purchase order expanded
the work plan to include a series of static tests wherein in­
strumented bolts were used to measure splice bolt loads.
Subsequent to the test program described herein, Franklin Steel Com­
pany contracted with TTl to conduct additional static load tests of sign­
posts. These tests were conducted to evaluate the strength of the Eze­
Erect system when 3/8 in., grade 8 splice bolts were used. Results of
these tests will be presented in TTl research report No. 4277-2F.
ACKNOWLEDGMENTS
The authors wish to express their appreciation to James W. Young of
Franklin Steel Company for his assistance and cooperation during the test
program. We are also appreciative of the work of Sylvia Velasco in
typing the report and correcting our grammatical miscues. Thanks also go
to Richard Zimmer for his help in the use and calibration of the instru­
mented bolts.
APPENDIX B - COMPARISON OF THEORETICAL DEFLECTIONS AND 80 ROTATIONS WITH EXPERIMENTAL RESULTS
APPENDIX C - TENSILE TESTS, 2.5 LB/FT AND 4.0 LB/FT SIGNPOSTS 92
APPENDIX D - TENSILE TESTS, 5/16 IN. GRADE 5 BOLTS 95
APPENDIX E- TENSILE TESTS, 5/16 IN. GRADE 8 BOLTS 97
REFERENCES 99
Results of Bending and Torsion Tests - 2.5 lb/ft Posts
Results of Bending Tests - 4.0 lb/ft Posts
Results of Bending and Torsion Tests - 4.0 lb/ft Posts
Results of Torsion Tests - 2.5 lb/ft Posts
Results of Torsion Tests - 4.0 lb/ft Posts
Results of Bending Tests - 4.0 lb/ft Posts
Results of Bending and Torsion Tests - 4.0 lb/ft Posts
Res~lts of Instrumented Bolt Tests - 2.5 lb/ft Posts under Bending Loading
Results of Instrumented Bolt Tests - 4.0 lb/ft Posts under Bending Load Configuration
Effective Moment Arm in Splice
Results of Instrumented Bolt Tests - 4.0 lb/ft Posts under Bending and Torsion Loading, Front Load
Results of Instrumented Bolt Tests - 4.0 lb/ft Posts under Bending and Torsion Loading, Front Load
Results of Instrumented Bolt Tests, 2.5 lb/ft Posts under Torsi on
Results of Instrumented Bolt Tests, 4.0 lb/ft Posts under Torsion
Results of Instrumented Bolt Tests, 2.5 lb/ft and 4.0 lb/ft Posts under Torsion with Modified Spacer Strap
Summary of Results of Static Tests
Comparison of Predicted Failure Loads with Test Results Bending Load, 2.5 lb/ft Posts
iv
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16
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19
32
33
36
37
42
43
47
49
50
53
54
55
63
70
LIST OF TABLES (continued)
Comparisqo of Predicted Failure Loads with Test Results, Bending Load, 4.0 lb/ft posts
Comparison of Bending Maximum Loads with Bending and Torsion Maximum Loads, 2.5 lb/ft and 4.0 lb/ft Posts
Comparison of Average Bolt Loads for Bending and Bending and Torsion Loading, 4.0 lb/ft Posts
Theoretical and Average Actual Deflections for 2.5 lb/ft Posts
Theoretical and Average Deflections for 4.0 lb/ft Posts
Tensile Tests of 2.5 lb/ft Signpost
Tensile Tests of 4. lb/ft Signpost
Tensile Tests, 5/16 in. Grade 5 Bolts
Tensile Tests, 5/16 in. Grade 8 Bolts
v
Page
71
74
75
84
85
93
94
96
98
Signpost Connection Details
Basepost-to-Signpost Connection Hardware
Load Configurations for Bending and Bending and Torsion Tests
Bending and Torsion Test Setup
Bending Only Test Setup
Bending Tests - 2.5 lb/ft Posts, Front Load
Bending Tests - 2.5 1b/ft Posts, Rear Load
Bending and Torsion Tests - 2.5 lb/ft Posts, Front Load
Bending and Torsion Tests - 2.5 lb/ft Posts, Rear Load
Bending Tests - 4.0 lb/ft Posts, Front Load
Bending Tests - 4.0 lb/ft Posts, Rear Load
Bending and Torsion Tests - 4.0 lb/ft Posts, Front Load
Bending and Torsion Tests - 4.0 lb/ft Posts, Rear Load
Typical Front Load Failure Mechanism for Bending Only and Combined Bending and Torsion Tests - 2.5 lb/ft and 4.0 lb/ft Posts
vi
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3
4
5
6
6
8
9
9
10
11
11
12
20
21
22
23
24
25
26
27
28
LIST OF FIGURES (continued)
Rear Load Failure Mechanism for 2.5 lb/ft Posts as a Result of Bending Only and Combined Bending and Torsion Tests
Typical Rear Load Failure Mechanism for 4.0 lb/ft Posts as a Re~ult of Bending Only and Combined Bending and Torsion Tests
Torsion Tests - 2.5 lb/ft Posts
Torsion Tests - 4~0 lb/ft Posts
Bending Tests - 4.0 lb/ft Posts, Front Load
Bending Tests - 4.0 lb/ft Posts, Rear Load
Bending and Torsion Tests - 4.0 lb/ft Posts, Front Load
Bending and Torsion Tests - 4.0 lb/ft Posts, Rear Load
Applied Load vs Bolt Load- 2.5 lb/ft Posts, Bending
Applied Load vs Bolt Load- 4.0 lb/ft Posts, Bending
Applied Load vs Bolt Load- 4.0 lb/ft Posts, Bending and Torsion
Applied Torque vs Bolt Load - 2.5 lb/ft Posts
Applied Torque vs Bolt Load - 4.0 lb/ft Posts
Basic Retainer-Spacer Strap used with 2.5 lb/ft Eze-Erect System
Basic Retainer-Spacer Strap used with 4.0 lb/ft Eze-Erect System
Modified Retainer-Spacer Strap used with 2.5 lb/ft Eze-Erect System
Modified Retainer-Spacer Strap used with 4.0 lb/ft Eze-Erect System
Splice Analysis
Transfer of Torque from Signpost to Basepost by the Connection
vii
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30
34
35
38
39
40
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44
45
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56
57
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59
60
61
67
73
Deflection Model for 2.5 lb/ft and 4.0 lb/ft Posts
Load vs Deflection - Comparison of Actual and Theoretical Results, 2.5 lb/ft Posts
Load vs Deflection - Comparison of Actual and Theoretical Results, 4.0 lb/ft Posts
Angle of Rotation vs Torque - Comparison of Theoretical with Actual Results, 2.5 lb/ft Posts
Angle of Rotation vs Torque - Cmoparison of Theoretical with Actual Results, 4.0 lb/ft Posts
viii
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76
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91
INTRODUCTION
Static 1 oad tests and fu 11-sca 1 e crash tests of the "first genera­
tion" Eze-Erect system were conducted at TTl during March, 1977 (!). Al­
though the test results met all requirements, analysis of these tests in­
dicated that improved performance could be gained by slight changes to the
design. After making these changes, further static load tests and full­
scale crash tests were conducted at TTl to evaluate the "second genera­
tion" assembly (£). Results of static load tests and full-scale vehicular
crash tests of a 6. 0 1 b/ft back-to-back U-post design were a 1 so presented
in reference 2.
The objective of the initial series of tests presented herein was to
further evaluate the static load carrying capacity of the Eze-Erect sys­
tem. Tests of 2.5 lb/ft and 4.0 lb/ft Eze-Erect systems were made with
5/16 in., grade 5 splice bolts. Bending, bending combined with torsion,
and pure torsion tests were conducted.
Subsequent to the initial series of tests it was determined that ca­
pacity of the 4.0 lb/ft Eze-Erect system could be increased by use of
grade 8 bolts. The next series therefore involved bending tests and bend­
ing combined with torsion tests of the 4.0 lb/ft Eze-Erect system with
5/16 in., grade 8 splice bolts.
The final series of tests involved the use of instrumented bolts in
the splice to measure bolt tension. The purpose of these tests was to
gain an insight into the load transfer mechanism through the post-to-base
splice.
1
TEST PROCEDURES
Phase I
A series of static load tests of 2.5 lb/ft and 4.0 lb/ft Eze-Erect
assemblies was conducted in Phase I. Cross-sectional properties of Frank­
lin Steel 2.5 lb/ft and 4.0 lb/ft U-posts are shown in Figures 1 and 2.
Each assembly consisted of a 3.5 ft basepost and a 12.5 ft signpost lapped
and nested together. The two posts were separated by a retainer-spacer
strap and fastened together with four 5/16 in., grade 5 bolts. Details of
the splice and hardware are shown in Figures 3 and 4.
Each signpost/basepost assembly was cut from the same stock. Coupons
were also taken from the stock and used to determine tensile strengths.
The pieces were assigned an ID number so each basepost/signpost assembly
could be matched with the appropriate tensile test results. Results of
these tensile tests, provided to TTl by Franklin Steel Company, are given
in Appendix C. Tensile tests were also performed on a representative sam­
ple of bolts used in the basepost-to-signpost splice, and the results are
given in Appendix D. These data were also provided by Franklin Steel Com­
pany.
Three basic types of static tests were conducted. Bending tests were
conducted on both sizes of signpost assemblies to determine ultimate mo­
ment capacities. Bending and torsion tests were made on both sizes of
signpost assemblies to determine the effect of an eccentric load on the
ultimate moment capacity. Pure torsion tests were conducted on the two
sizes of signposts to determine their torsional stiffnesses.
2
0.1875 11
T yy
Zxx = • 383 in. 3
0.23'!
I y-y = 1.190 in.4
s = .560 in.3 x-x ~ \. 1 I \ \ n ?~"---- I I s = .680 in.3 y-y
Zxx = .714 in.3
U"l
I
:---o-0 --o--0 _Q_(Q)_Q 1 (Q)-0- -o- _Q_(Q)_ I L --- - - -- - -- - - - - -- -1- - - - -- - - - - -
(Q)
- - - - - - -- - - -r- - ~ -- --1 -1 - ~ ----;.-- -- ------- L....! ..__- --r ---- -----L - -- -- -- -- -- -- -- -- -- -- 1;-.-:..rr-', I I _,.,
SIGNPOST
&..<1 -- 1----~----- 1: ;~,r-------- 1 I I ¥"-;" LJ I !...J
BASE POST
~l1112'~
~ ~ % 1/ }
Figure 5. Assembled Post in Fixed Connection.
6
Bending and bending and torsion tests were conducted on signpost as­
semblies cantilevered from a fixed connection as shown in Figure 5. Load­
ing configurations for these tests are shown in F1gure 6. The load, 11 P11 ,
was composed of the we(ght of the loading apparatus (bucket, bracket, and
bolt) plus lead shot added to increase 11 P11 to the desired value. The mo­
ment arm remained constant at 145 in. for both sizes of post. The eccen­
tricity, .. e .. , of the load in the bending and torsion tests was 4.5 in. for
the 2.5 lb/ft posts and 5.4 in. for the 4.0 lb/ft posts. These .. e .. values
are representative of those specified by the American Association of State
Highway and Transportation Officials (AASHTO) (l) for the size signs typi­
cally used on these signposts. Figures 7 and 8 show the actual bending
and bending and torsion tests as they were conducted.
Pure torsion tests were conducted on a 10-ft section of signpost
only, with no intermediate splice to a basepost. A special device devel­
oped to perform these tests is shown in Figure 9. Direct reading of the
applied torque was made by use of calibrated strain gages mounted along
the shaft of the testing device. Use of the torsion testing device is il­
lustrated by tests on a 4.0 lb/ft post shown in Figures 10 through 12.
Phase II
Test procedures in Phase II were the same as Phase I with three ex­
ceptions. First, grade 8 bolts were used in the signpost-to-basepost
splice. Second, tests were conducted on the 4.0 lb/ft post only. Repeat
of the 2.5 lb/ft assembly tests was unnecessary since it was obvious the
grade 8 bolts would not change the elastic strength of the 2.5 lb/ft as­
sembly. Third, no pure torsion tests were conducted.
7
co
p .---------.
2.5 lb/ft Posts - e = 4.5 11
BENDING ONLY 4.0 lb/ft Posts - e = 5.4 II (Typical for 2.5 and 4.0 lb/ft Posts)
BENDING AND TORSION
Figure 6. Load Configurations for 11 Bending 11 and 11 Bending and Torsion 11 Tests.
Figure 7. Bending and Torsion Test Setup.
Fi:,:l'e E~. Bending Only Test Setup.
9
• I • " •,
l 0
Figure 10. 4.0 lb/ft Post Torqued to 45°.
F i gu 1· ~ 11 . 0 4.0 1b/ft Post Torqued to 90 .
11
I
1 2
Given in Appendix E are results of a series of tensile test"s of
5/16 in., grade 8 bolts, taken from the lot used in Phase II. These re­
sults were provided by Franklin Steel Company.
Phase III
Testing in Phase III involved the use of instrumented bolts in the
signpost-to-basepost splice. The bolts, manufactured by Strainsert Corpo­
ration (!), were calibrated to provide the tensile load in the bolt.
Bending and bending and torsion tests were conducted, with both front and
rear loads, on the 4.0 lb/ft Eze-Erect system. Bending tests were conduc­
ted, with both front and rear loads, on the 2.5 lb/ft Eze-Erect system.
Pure torsion tests were conducted on 2.5 lb/ft and 4.0 lb/ft Eze-Erect
systems.
13
Test results are presented in both tabular and graphical formats.
Tables and graphs of bending test data contain the following items:
Load - Load applied 145 in. from the fixed connection;
includes weight of test fixtures and equivalent
dead weight due to the post itself.
Moment - Moment induced by 1 oad in the basepost at the
fixed connection.
applied.
An ID number for each signpost/basepost combination is included (e.g.,
S-5-2.5), along with the load at failure and the location of the failure
for each test.
Tables and graphs of the bending and torsion test data contain the
following information:
Load - Same definition as above.
Eccentric Load - Portion of load that acts a distance "e" offset
from centroid of signpost.
Effective Torque - Torque induced on signpost by eccentric load and
adjusted for rotation in signpost.
Rotation - Rotation of signpost at cross section where load
is applied, measured in degrees.
As in the bending tests, the ID number for each assembly is included,
along with the load at failure and location of the failure for each sepa­
rate test. Reference should be made to Figure 3 for bolt failure loca­
tion.
14
Tables and graphs of the pure torsion test data contain the following
information:
Torque- Pure torque applied at end of post.
Phase I
Results of Phase I tests with the grade 5 bolts are given in Tables 1
through 4 and Figures 13 through 20. These tests produced distinct fail­
ure modes dependent on the type of test, size of post, and direction of
loading. Failure modes in the splice observed were generally consistent
with the theoretical analysis presented in Appendix A.
The mode of failure for both 2.5 lb/ft and 4.0 lb/ft posts front
loaded under bending and bending and torsion is shown in Figure 21. In
each case, bolt .. A .. (see Figure 3) fractured, causing collapse of the
signpost assembly. Bolt failure occurred before significant yielding of
the basepost or signpost. Failure mode for the 2.5 lb/ft posts rear
loaded under the action of bending and bending and torsion is shown in
Figure 22. In this case, fracture of the post occurred. The mode of
failure for the 4.0 lb/ft post rear loaded under the action of bending and
bending and torsion is shown in Figure 23. In this case, bolt 11 811 frac­
tured before yielding of the signpost or basepost. Analysis of the re­
sults indicates that the eccentrically loaded posts (bending and torsion)
fail at a load that is not appreciably less than the failure load for
bending only. Typically, failure loads for the eccentrically loaded posts
were within 10 percent of the failure loads for bending only.
It is noted that the "design moment .. capacity of the posts, computed
by multiplying the section modulus (Sxx) by the minimum yield strength
{60,000 psi), is as follows:
15
Table 1. Test Results: Bending, 2.5 lb/ft Posts
Front Load Rear Load Load Moment (lbs) (lQ-in) S-5-2.5 S-6-2.5 S-7-2.5 S-12-2.5 S-13-2.5 S-14-2.5
45.0 6525 6.8 9.1 10.6 .7.2 7.3 7.4 55.0 7975 8.5 10.9 12.3 9.1 8.8 9.1 65.0 9425 10.2 12.4 14.0 10.8 10.4 11.1 75.0 10875 12.4 14.4 15.8· 12.6 12.2 12.9 85.0 12325 14.3 16.2 17.6 14.6 14.0 14.9 95.0 13775 16.3 18.2 19.6 16.5 15.6 16.1
105.0 15225 18.3 20.1 21.4 18.0 17.5 17.9 __. 115.0 16675 20.2 22.1 23.4 20.3 1!9.4 19.7 0\
125.0 18125 22.2 24.1 25.2 22.2 .. 21.3 21.7 135.0 19575 24.0 26.2 27.0 24.0 23.1 23.3 145.0 21025 25.9 28.2 28.8 25.9 24.9 25.2 155.0 22475 28.2 30.2 30.8 27.8 . 27.0 27 .• 1 165.0 23925 30.7 32.4 32.6 29.9 28.5 29.1 175.0 25375 33.4 35.0 34.5 32.1 30.3 31.1 185.0 26825 36.6 37.9 36.5 35.0 33.3 . 33.4 195.0 28275 Failure Fai 1 ure 38.5 38.9 35.3 36.2 205.0 29725 (B!)lt 11A11 ) (Bolt "A") Fai 1 ure Failure 38.8 39.6 215.0 31175 (Bolt 11A11 ) (Basepost) 43.1 Failure 225.0 32625 Failure (Signpost)
{Basepost)
Moment Ar~ = 145 in. {See Figure 6) Grade 5 Bolts
Table 2. Test Results: Bending and Torsion, 2.5 lb/ft posts.
Front Load Rear Load
S-1-2.5 S-2-2.5 S-3-2.5 S-8-2.5 S-10-2.5 S-11-2.5 Moment Eccentric Eff. Eff. Eff. Eff. Eff. Eff.
Load (1b-in) Load Torque Rot. Torque Rot. Torque Rot. Torque Rot. Torque Rot. Torque Rot. ( 1 b) ( 1 b) (lb-in) (deg) (lb-in) (deg} (lb-in) (deg} (lb-in) (deg) (1b-in) (deg) (lb-in) (deg)
46.4 6728 25.8 99.2 11.0 100.1 10.5 99.2 11.0 98.3 11.5 98.3 11.5 99.2 11.0 56.4 8178 35.8 129.1 14.5 129.1 14.5 129.1 14.5 129.1 14.5 129.1 14.5 130.3 14.0 66.4 9628 45.8 160.2 16.0 155.2 17.5 156.9 17.0 156.9 17.0 155.2 17.5 "'156. 9 17.0 76.4 11078 55.8 187.0 18.0 178.7 20.0 180.8 19.5 187.0 18.0 174.4 21.0 180.8 19.5 86.4 12528 65.8 210.7 20.0 198.0 22.5 203.1 21.5 208.2 20.5 195.4 23.0 200.6 22.0 96.4 13978 75.8 231.1 22.0 219.1 24.0 225.1 23.0 231.1 22.0 213.0 25.0 219.1 24.0
106.4 15428 85.8 254.8 23.0 237.7 25.5 241.1 25.0 251.4 23.5 230.7 26.5 241.1 25.0 __. 116.4 16878 95.8 276.9 24.0 249.7 27.5 253.6 27.0 269.2 25.0 249H 27.5 257.6 26.5 -.....J
126.4 18328 105.8 288.8 26.0 267.0 28.5 262.5 29.0 293.1 25.5 271.4 28.0 275.7 27.5
136.4 19778 115.8 297.0 28.0 292.2 28.5 257.8 32.0 311.3 26.5 287.3 29.0 292.2 28.5 146.4 21228 125.8 322.7 28.0 317.4 28.5 258.3 34.0 333.1 27.0 301.6 30.0 306.9 29.5
156.4 22678 135.8 325.5 30.0 284.7 33.5 254.9 36.0 353.9 27.5 319.8 30.5 319.8 30.5 166.4 24128 145.8 324.6 32.0 267.2 36.5 234.6 39.0 361.8 29.0 337.1 31.0 337.1 31.0
176.4 25578 155.8 * 257.7 38.5 250.7 39.0 380.0 29.5 353.6 31.5 360.2 3t.O
186.4 27028 165.8 * Failure 397.4 30.0 369.1 32.0 369.1 32.0 196.4 28478 175.8 (Bolt "A") 421.4 30.0 276.2 33.0
F~ilure 206.4 29928 185.8 Failure Failure (Ba~epost)
(Basepost) (Signpost) *These tests were suspended before failure due to the
limits of the testing device. Modifications were Moment Arm = 145 in. made and the third front load test was carried on (See Figure 6) to failure.
Grade 5 Bolts
Load Moment FrQnt Load Re~r L.oad
( 1 bs) (1 b-in) S-4.-1 S-4.0-2 S-4.0-3 S-4.0-8 S-4.0-9 S-4.0-10
54.7 7932 6.2 6.9 6.8 3.2 3.3 3.1 64.7 9382 7.3 7.9 7.8 4.1 4.3 4.0 74.7 10832 8.4 8.8 9.2 5.0 5.3 4.9 84.7 12282 9.3 9.9 10.4 5.9 6.3 6.1
94.7 13732 10.4 11.1 11.6 6.9 7.2 7.2 104.7 15182 11.5 12.4 12.7 7.9 8.3 8.4
114.7 16632 12.6 13.6 13.9 9.0 9.5 9.7
124.7 18082 14.0 14.8 15.2 9.9 1 o. 7 10.8
134.7 19532 15.3 16. 1 16.4 10.9 12. 1 12.3 __,
I
co 144.7 20982 16.7 17.5 17.6 12.1 13~4 13.5
154.7 22432 18.1 19.0 19.1 13.2 14.6 14.7
164.7 23882 19.7 20.7 20.8 14.4 · 15. R 15.7
174.7 25332 21.6 Failure 22.6 15.7 16.8 16.8
184.7 26782 Failure (Bolt 11 A11 ) Failure 16.7 17.9 18.0
194.7 28232 (Bolt 11 A11 ) {Bolt 11A11 ) 18.2 19.2 19.2
204.7 29682 19.5 20.4 20.6
214.7 31132 21.0 21.9 22.0
224.7 32582 Fai 1 ure 23.3 23.9
234.7 34032 (Bolt 11 B11 ) 25.2 Failure
244.7 35482 Failure {Bolt 11 B11 )
Moment Arm = 145 in. (Bolt 11 B11 )
(See Figure 6) Grade 5 Bolts
Table 4. Test Results: Bending and Torsion, 4.0 lb/ft Post
Front load Rear Load
S-4.0-5 S-4.0-6 S-4.0-7 S-4.0-11 S-4.0-12 S-4.0-13 Moment Eccentric Eff. Eff. Eff. Eff. Eff. Eff.
Load (1 b-in) Load Torque Rot. Torque Rot. Torque Rot. Torque Rot. Torque Rot. Torque Rot. ( 1 b) ( 1 b) (lb-in) (deg) (lb-in) (deg) (lb-in) (deg) (lb-in) (deg) (lb-in) (deg) (lb-in) (deg)
56.5 8193 25.8 130.5 6.0 132.0 5.0 131.3 5.5 130.5 6.0 131.3 5.5 131.3 5.5
66.5 9643 35.8 176.5 8.0 179.9 6.5 179.9 6.5 176.5 8.0 176. 5 8.0 177.6 7.5
76.5 11093 45.8 221.3 9.5 222.8 9.0· 224.3 . 8.5 219.7 10.0 221.3 9. 5 . 222.8 9.0 ~
86.5 12543 55.8 261.9 11.5 265.8 10.5 265~8 10.5 259.5 12.0 261.9 11.5 263.8 11.0
96.5 13993 65.8 299.4 13.5 308.8 11.5 308.8 11.5 297.0 14.0 301.8 13.0 304.2 12.5 106.5 15443 75.8 339.3 14.5 344.9 13.5 342.1 14.0 333.7 15.5 339.3 14.5 342.1 14.0
116.5 16893 85.8 371.1 16.5 380.9 15.0 380.9 15.0 374.4 16.0 374.4 16.0 380.9 15.0
126.5 18343 95.8 407.0 17.5 418.1 16.0 410.7 17.0 403.2 18.0 407.0 17.5 414.4 16.5 1.0
136.5 19793 105.8 436.9 19.0 449.4 17.5 445.3 18.0 428.3 20.0 441.1 18.5 449.4 17.5
146.5 21293 115.8 468.8 20.0 478.1 19.0 478.1 19.0 459.3 21.0 473.5 19.5 478.1 19.0
156.5 22693 125~3 493.7 21.5 509.3 20.0 499.0 21.0 493.7 21.5 499.0 21.0 504.1 20.5
166.5 24143 135.8 515.8 23.0 538.6 21.0 Failure 515.8 23.0 533.0 21.5 533.0 21.5
176.5 25593 145.8 553.8 23.0 560.0 22.5 (Bolt 11 A") 541.3 24.0 553.8 23.0 560.0 22.5
186.5 27043 155.3 Failure Failure 544.4 26.5 578.5 24.0 591.8 23.0
196.5 28493 165.8 (Bolt 11 A") (Bolt "A") 571.9 27.0 601.2 25.0 615.6 24.0
206.5 29943 175.8 598.5 27.5 629.8 25.5 Failure 216.5 31393 185.8 615.8 28.5 Failure (Bolt 11 811 )
226.5 32843 195.8 Failure (Bolt "B") Moment Arm = 145 in. (Bolt 11 811 )
(See Figure 6) Grade 5 Bolts
200
150
X = POINT OF FAILURE
40
N __,
200
X= POINT OF FAILURE
S-13-2.5
40
50
X= POINT OF FAILURE
25 30
35 40
I
50~
5
30 35
N +:>
200
150
X= POINT OF FAILURE
30
100
50
X= POINT OF FAILURE
30
200
N 0 ()) 0
X= POINT OF FAILURE
30
30
Note identical bolt failure in each case.
F i g u r e 21 . T y ;:d c a 1 F r o 'l t L o a d Fa i 1 u r e He c h a n i s m for Bending Only and Co~bined Bending and Torsion Tests for 4.0 1b/ft and 2.5 1b/ft f"'.~1sts.
Fat1ure occurred in post and not in bo7ts.
-.
Figure 22. 0 ea,· load FaiJu,·e '·1echanism fo,· 2.5 lbift Posts
as a Result of Rending Only and Co,••bined Bending 3Gd Torsion Tests.
?9
Note identical bolt failure in each case.
F i g u r e 2 3 . T y p i c a l q_ e a l" Load Fa i l u r e t1 e c h a n i s m for 4.0 lb/ft Posts as a Result of Send i '~9 Only and Cor,bi ned Sending and Ttli"Sil\n Tests.
30
POST
17,340
33,600
Comparing these values with the bending moment at failure in the tests
shows that 5/16 in., grade 5 bolts -are of sufficient strength to pennit
the full design moment to be developed in the 2.5 lb/ft Eze-Erect system
but insufficient for the 4.0 lb/ft Eze-Erect system.
Results of pure torsion tests are given in Tables 5 and 6 and Fig-
ures 24 and 25. Five tests were conducted on each of the two post sizes.
These tests, on 10-ft lengths of posts without the bolted connection, were
conducted to determine the torsional stiffness of each post.
Phase II
Results of the tests with the grade 8 bolts are given in Tables 7 and
8 and Figures 26 through 29. The modes of failure in these tests were
similar to those in Phase I, i.e., bolt 11A11 fracture for front loading and
bolt 11 811 for rear loading. As expected, the failure loads and moments
were higher in Phase II due to the increased strength of the splice bolts.
However, the tests indicated that 5/16 in., grade 8 bolts did not permit
development of the full design moment capacity of the 4.0 lb/ft post. It
became clear· after these tests that a better understanding of the load
transfer mechanism through the splice was needed to more accurately design
the 4.0 lb/ft Eze-Erect system.
Phase II I
Results of the instrumented bolt tests for bending loads are given in
Tables 9 and 10 and Figures 30 and 31. Reference should be made to
31
S-1-2.5 S-2-2.5 S-3-2.5 S-5-2.5 S-9-2.5
Rotation Torque Rotation Torque Rotation Torque Rotation Torque Rotation Torque (deg) (lb-in) (deg) {lb-in) (deg) {lb-in) {deg) {lb-in) (deg) (lb-in)
0 0 0 0 0 0 0 0 0 0
10 63.7 10 87.6 10 63.7 10 47.8 10 39.8
20 159.4 20 127.5 20 143.4 20 127.5 20 119.5
30 239.0 30 207.2 31 247.0 30 223.1 30 207.2
40 326.7 41 294.2 40 318.7 40 302.8 41.5 318.7
51 406.3 50 374.5 50 406.3 50 382.4 50 382.4
60 470.1 60 438.2 60.5 478.1 61 459.2 60 494.0
70 549.8 70 509.9 70 557.7 70 533.8 70 549.8
80 629.4 80 581.6 80.5 661.3 80.5 621.5 80 629.4
90.5 685.2 90 653.3 90.5 733.0 90 693.2 90 701.1
Test Length = 10 ft
S-3-4 S-S-4 S-12-4 S-13-4 S-14-4
Rotation Torque Rotation Torque Rotation Torque Rotation Torque Rotation Torque (deg) (lb-in) (deg) (l b-in) (deg) (lb-in) (deg) (lb-in) (deg) (lb-in)
0 0 0 0 0 0 0 0 0 0
10 231.1 10 199.2 10 207.2 10 21S. 1 10 1Sl.4
20 470.1 20 414.3 20 422.3 20 478.1 20.S 382.4
30 701.1 30 669.3 30 6S3.3 30 733.0 30 64S.4
40 948.1 40 900.3 40 884.4 40 980.0 40 900.3
so 1211.1 so 1139.4 so 1131.4 so 1266.8 Sl.S 1139.4
60 1466.0 60 1410.3 60 1378.4 60 1S4S.7 60 l346.S
70 1721.0 70 1641.3 70 1617.4 70 1808.6 70.S 1569.6
80 1976.0 80 1896.3 80 1864.4 80 2087.S 80 1808.6
90 2222.9 90 213S.3 90 2111.4 90 2350.4 90.S 2047.7
100 2477.9 100 2374.3 100 2366.4 100 2629.3 100 2270.8
110 2709.0 110 2S97.4 110 2597.4 110 2892.2 111.0 2S6S.S
120 2948.0 120 2828.S 120 2828.5 120 3147.2 122 2835.4
Test Length = 10 ft
300
200
34
S-3-2.5
. S-9-2.5
80
35
S-13-4.0
Front Load Load Moment ( 1 bs) ( 1 b-in) S-5-4.0 S-12-4.0
74.7 10832 9.4 8.5
124.7 18082 16.0 14.0
174.7 25332 22.2 21.4
184.7 26782 23.7 22.6
194.7 28232 25.1 24.3
204.7 29682 26.7 25.9
214.7 31132 28.1 28.0
224.7 32582 30.2 30.0
234.7 34032 Failure Failure
254.7 36932
264.7 38382
274.7 39832
* At this load several threads were stripped on the tension bolt causing the large
deflection.
S-13-4.0
Failure (Bolt 11 A11 )
21.9 17.9
Failure Failure
Moment Arm = 145 in. (See Figure 6) Grade 8 Bolts
S-9-4.0
6.7 11.7 17.3 18.6 19.8 20.9 22.2 23.4 29.4* 30.6
Failure (Bolt "B")
Table 8. Test Results: 11 Bending and Torsion, .. 4.0 lb/ft Posts
Front Load Rear Load
S-1-4~ S-6-4.0 S-7-4.0 S-3-4.0 S-4-4.0 S-10-4.0
Moment Ec<;entric Eff. Eff •• Eff. Eff. Eff. Eff. Load (lb-in) Load Torque Rot. Torque .Rot~ Torque Rot. Torque Rot. Torque Rot. Torque Rot. ( 1 b) ( 1 b) (lb-in) (deg) (lb-in) (deg) (lb-in) (deg) (1b-in) (deg) (1b-in) (deg) (1b-in) (deg)
76.5 11093 45.8 225.8 8.0 225.8 8.0 225.8 8.0 228.7 7.0 225.8 8.0 225.8 8.0
126.5 18343 95.8 439.4 13.0 439.4 13.0 432.4 14.0 446.3 12.0 432.4 14.0 432.4 14.0
176.5 25593 145.8 613.6 18.0 619.4 17.5 613.6 18.0 625.0 17.0 613.6 18.0 636.3 16.0
186.5 27043 155.8 643.3 19.0 649.5 18.5 643.3 19.0 661.8 17.5 649.5 18.5 667.9 17.0
196.5 28493 165.8 671.2 20.0 684.6 19.0 677.9 19.5 697.8 18.0 677..9 19.5 697.8 18.0 w 206.5 29943 175.8 718.8 19.5 704.5 20.5 732.9 18.5 711.7 20.0 725.9 19.0 ...., Fai 1 ure
216.5 31393 185.8 (Bolt 11A11 ) Failure 736.9 21.0 767.2 19.0 744.6 20.5 752.2 20~0
226.5 32843 195.8 (Bolt 11 A11 ) Failure 800.6 19.5 776.6 21.0 784.7 20.5
236.5 34293 205.8 (Bolt 11 A11 ) -- * 807.7 21.5 -- * 246.5 35743 215.8 * -- * -- * 256.5 37193 225.8 -- * -- * Failure
266.5 38643 235.8 Fai 1 ure Failure (Bolt 11 B11 )
(Bolt 11 B11 ) (Bolt 11 B11 )
* No Measurement Taken Moment Arm = 145 in. (See Figure 6) Grade 8 Bolts
250
200
X= POINT OF FAILURE
5~12-4.0
30 35
1.0 .J
X= POINT OF FAILURE I / /
50
0 5 10 15 20 25 30 35 40 DEFLECTION, (IN.)
Figure 27. Bending Tests - 4.0 lb/ft Posts, Rear Load.
250
I // GRADE 8 BOLTS FRONT LOAD
50~ / X = POINT OF FAILURE
0~-----------------.-----------------.r-----------------,-----------------~--------------~------------, 0 5 10 15 20 25 30
ROTATION, (DEG)
Figure 28. Bending and Torsion Tests - 4.0 lb/ft Posts, Front Load.
250
200
100 .j:::> u LaJ
X = POINT OF FAILURE
~ N
105. 115.
Table 9. Results of Instrumented Bolt Tests - 2.5 lb/ft Posts under Bending Loading
Front Load - Bolt 11 A11 In Tension Rear Load - Bolt 11 B11 In Tension
S-3.2.5 S-7-2.5 S-2-2.5 S-1-2.5 S-6-2.5 S-5-2.5 Bolt Load Bolt Load Bolt Load Average Bolt Load Bolt Load Bolt Load
( 1 b) ( 1 b) ( 1 b) ( 1 b) ( 1 b) ( 1 b) ( 1 b)
1303 1277 1283 1288 1503 1449 1359
2751 2416 2435 2534 2141 2383 2402
3208 2917 2839 2988 2482 2720 2738
3663 3455 3233 3450 2826 3009 3050 4112 3851 3590 3951 3147 3321 3342
4545 4232 3931 4236 3477 3635 3645
4984 4602 4238 4608 3791 3937 3937 5408 4968 4550 4975 4093 4225 4193
5797 5361 4862 5342 4374 4485 4475
* Bolt Loads along this row are due to pre1oading of the bolts from
tightening the connection
Average ( 1 b)
~ w
Table 10. Results of Instrumented Bolt Tests - 4.0 lb/ft Posts under Bending Load Configuration
Front Load - Bolt "A" In Tension Rear Load - Bolt "B" In Tension
S-7-4.0* S-4-4.0 S-2-4.0 S-6-4.0 S-1-4.0 S-12-4.0 Load Bolt Load Bolt Load Bolt Load Average Bolt Load Bolt Load Bolt Load ( 1 b) ( 1 b) (1 b) ( 1 b) ( 1 b) ( 1 b) ( 1 b) ( 1 b)
0.** 1135 1068 1102 1319 1339 1326 54.7 3050 2808 2929 2623 2660 2628 64.7 3507 3298 3403 2915 2982 2915 74.7 3984 3761 3873 3197 3284 3232 84.7 4471 4215 4343 3495 3588 3551 94.7 4947 4669 4808 3809 3891 3861
104.7 5444 5124 5284 4123 4171 4210 114.7 5896 5597 5747 4426 4478 4583 124.7 6357 6055 6206 4738 4782 4968
*Instrumentation malfunctioned during this test and data found to be invalid. **Bolt loads along this row are due to preloading of the bolts from tightening the connection.
Moment Arm = 145 in. (See Figure 6)
Average (1 b)
~ ~
!:: 4000
lb- load
m = 30 .II -_,;:,..:::=
o~-~-~-~-~-~---r--~--~--~--~--~~----~--~ 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Effective Post Load, (I bs)
Figure 30. Applied Load vs Bolt Load - 2.5 lb/ft Posts Bending.
7000
-g 5000 0
~ lb-tlglt m = 31.47 t) I b-lood Cl 2000 e t)
> c:t
1000
0~-----~------r-----~-----~----------~-----~------r-----~----------~-----~------r-----~----------r-~ 0 10 20 30 40 50 60 70 80 90 100 I 10 120 130 140
Effective Post Load, (lbs)
Figure 31. Applied Load vs Bolt Load - 4.Q lb/ft Posts, Bending.
Figure 3 for bolt 11A11 and 11811 locations. Plotted in Figures 30 and 31 are
the average values from the respective loadings. Also shown on the two
figures is slope 11m11 of the 11 Straight line .. portion of each plot.
Of primary interest in these tests was the 11 effective moment arm 11 in
the splice when the post was front loaded (rear loading not as critical as
front loading). As derived in Appendix A, the effective moment arm, 11 b11 ,
is computed by
where P =effective post load (see Figure Al}
R8 =load in bolt 11A11 (see Figure Al}
Using this formula and the average load in bolt 11 A11 from Tables 9 and
10, values of 11 b11 were computed and are shown in Table 11. Two points of
interest were noted in these results. First, at the higher loads the val-
ue of 11 b11 was 3.1 in. for the 2.5 lb/ft post and 2.9 in. for the 4.0 lb/ft
post. Second, values of .. b .. increased with increasing post load. The
latter occurrence is attributed to rotation of the signpost relative to
the basepost forcing the resultant compressive force {Rc in Figure Al} to
move toward bolt 11 811 • Further loading of the post in these tests was pro-
hibited due to the load limitation of the instrumented bolt.
Considering the 4.0 lb/ft system, and assuming an effective moment
arm of 3.0 in., the allowable post load, P, would be
{ 3.0 ){ R8) p = 139.25
Table 11. Effective Moment Arm in Splice
2.5 lb/ft Post 4.0 lb/ft Post Effective Pos~verage Load in Effective Moment Effective Post Average Load 1 n Tfre-cti ve Moment
Load, P Bolt 11 A11 , Rs Arm, b Load, P Bolt 11A11 , RB Arm, b {1 b} {1 b} {in.} {1 b} {1 b} {in.)
45 2534 2.5 54.7 2929 z. 7
55 2988 2.6 64.7 3403 2.7
65 3450 2.7 74.7 3873 2.7
75 3951 2.7 84.7 4343 2.8
.+::> 85 4236 2.9 94.7 4808 2.8
........
Now, R B = {stress area of bolt) (cry of bolt)
For a 5/16 in., grade 8 bolt
So
p = (3.0){7830) = 168.7 lb 139.25
The moment at the groundline would be
M = 168.7{145) = 24,460 lb-in.
Since the elastic moment capacity of the 4.0 lb/ft post is 33,600 lb-in.,
the 5/16 in. grade 8 bolts permit a load or moment of about 73 percent of
the capacity of the 4.0 lb/ft post.
One possible way to increase the capacity of the splice would be to
redesign the retainer-spacer strap to increase the effective moment arm.
This could be accomplished by reducing the bearing surface of the strap
near bolt "8 11 , forcing the resultant compressive force {Rc in Figure Al)
toward bo 1 t "B 11 • An increase in 11 b 11 trans 1 ates into a reduced tensile
load in bolt 11A11 , thereby increasing the capacity of the splice. An in­
crease in the bolt size would also increase the capacity of the splice.
Shown in Tables 12 and 13 and Figure 32 are results of bending and
torsion tests on 4.0 lb/ft Eze-Erect posts using instrumented bolts. Re-
sults of these tests were similar to those in the bending tests, and the
effective moment arm, b, was quite similar. Torsion on the post does not
appreciably affect the tensile load in the splice bolts (as shown in the
subsequent tests).
Preload --- 56.5 8193 25.8 66.5 9643 35.8
76.5 11093 45.8 86.5 12543 55.8
.Po 96.5 13993 65.8 \.()
Table 12. Results of Instrumented Bolt Tests - 4.0 lh/ft Posts under Bending and Torsion Loading, Front Load
Bending and Torsion 4.0 lb/ft Posts Front Load
S-6-4.0 S-1~4.0
( 1 b-in) Rot. (0 ) ( 1 b) Tor. (lb-in) Rot. (0 )
0 1112 0
191 . 7 7.5 3483 191.9 7
243.9 9.5 4010 244.3 9
295.3 11.5 4623 295.3 11.5
345.5 13.5 5245 345.5 13.5
S-12-4.0 Bolt Load Eff. ( 1 b) Torque Rot. (0 )
1098 -- 0
Avg. Bolt Bolt Load Load ( 1 b) ( 1 b}
977 1062 2464 2866
Ecc. Load Moment Load ( 1 b) (lb-in) ( 1 b)
Preload -- -- 56.5 8193 25.8 66.5 9643 35.8 76.5 11093 45.8 86.5 12543 55.8 96.5 13993 65.8
g; 106.5 15443 75.8 116.5 16893 85.8 126.5 18343 95.8 136.5 19793 105.8
Table 13. Results of Instrumented Bolt Tests - 4.0 lb/ft Posts under Bending and Torsion Loading, Front Load
Bending and Torsion 4.0 lb/ft Posts, Rear Load
S-4-4.0 S-7-4.0 Bolt Bolt
Eff. Torque Load Eff. Load ( 1 b,-i n) Rot. (0 ) ( 1 b) Tor. (lb-in) Rot. (0 ) ( 1 b)
0 1002 --- 0 1321
243.9 9.5 2927 243.2 1 o. 5 3041
295.3 11.5 3112 294.2 12.5 3259
345.5 13.5 3416 344.0 14.5 3521
393.5 16.0 3744 392.0 16.5 3872
441.9 17.5 4091 439.4 18.5 4205
484.6 20.5 4457 484.6 20.5 4585
529.7 22.0 4937 529.7 22.0 4936
S-8-4.0
139.0 4 192.3 6 244.6 8.5 296.3 10.5 34q;9 12.5
396.3 14.5 444.2 16.5 490.6 18.5 535. 1 20.5
Moment Arm = 145 in. (See Figure 6)
Avg. Bolt Bolt Load Load (1 b) ( 1 b)
1294 1206 2561 2421 2851 2705
3174 3047 3487 3286 3810 3582 4143 3920 4518 . 4271
4870 4637 5193 5022
FRONT LOAD
60 70
I b-lood
80 90 100 110 120 130 140 Effective Post Load, ( lbs}
Figure 32. Applied Load vs Bolt Load - 4.0 lb/ft Posts, Bending and Torsion.
Tables 14 through 16 and Figures 33 and 34 contain results of a
series of pure torsi on tests of Eze-Erect systems using instrumented
bolts. Two of the tests involved a modified retainer-spacer strap. Fig­
ures 35 and 36 show the basic straps, and Figures 37 and 38 show the modi­
fied straps. Results indicate the modified straps had no significant af­
fect on the load in bolt during torsional loading. (Additional bending
tests with the modified straps were planned but later cancelled since
Franklin Steel decided to redesign the strap. Tests of the redesigned
strap are presented in Research Report 4277-2F.) Analysis of the pure
torsion results indicate that the tensile load in the splice bolts is not
greatly affected by torsion. In some cases the bolt load actually de­
creased with increasing torque. A discussion of torque transfer mecha­
nisms through the splice- is given in Appendix A.
52
Table 14. Results of Instrumented Bolt Tests, 2.5 1 b/ft Posts under Torsion
S-1 - 2.5 S-5 - 2.5 S-6 - 2.5
Bolt 11 A11 Bolt 11 B11 Bolt 11A11 Bolt 11 B11 Bolt 11 A" Bolt "B" Rotation Torque Load Load Torque Load Load Torque Load Load
(Degrees) (1b-in) ( 1 b) ( 1 b) (lb-in) ( 1 b) (1 b) (lb-in) ( 1 b) (1 b)
00 (Preload) 0 1036 883 0 1050 1097 0 608 946
10 39.8 998 795 79.7 1036 1102 39.8 580 926 20 159.4 969 785 127.5 1007 1131 103.6 527 926 30 199.2 950 785 183.3 983 1146 167.3 504 926
<..T1 40 278.9 922 Z95 262.9 969 1156 223.1 494 951 w
50 358.5 907 805 318.7 955 1165 302.8 485 985 60 438.2 893 824 382.4 941 1165 358.5 480 1024 70 517.9 879 839 438.2 926 1170 430.2 475 1068 80 597.6 865 858 541.8 912 1170 494.0 475 1112 90 677.2 855 887 637.4 898 1170 597.6 466 1151
100 796.8 846 902 733.0 888 1146 677.2 456 1200 110 860.5 874 1131
Table 15. Results of Instrumented Bolt Tests, 4.0 lb/ft Posts under Torsion
Torsion Tests - 4.0 lb/ft Posts
S-4 - 4.0 S-12 - 4.0 S-7 - 4.0
Bolt "A" Bolt "B" Bolt "A" Bolt "B" Bolt "A" Bolt "B" Rotation Torque Load Load Torque Load Load Torque Load Load (Degrees) (lb-in) ( 1 b) ( 1 b) (lb-in) ( 1 b) ( 1 b) (1 b-in) ( 1 b) ( 1 b)
00 0 741 974 0 1009 660 0 878 684
10° 247 751 960 255 995 641 255 975 665
20° 478 761 983 486 990 641 494 1053 684
tn 30° 701 746 1040 685 970 679 733 1112 689 ~
40° 884 736 1088 876 961 727 924 1214 722
50° 1163 741 1088 1092 965 774 1171 1375 770
60° 1418 731 1112 1315 965 841 1386 1609 789
70° 1617 761 1117 1538 995 936 1641 1824 817
80° 1864 766 1112 1793 1029 1055 1872 2136 879
90° 2072 809 1155 2024 1073 1178 2119 2448 941
Table 16. Results of Instrumented Bolt Tests, 2.5 lb/ft and 4.0 lb/ft Posts under Torsion with Modified Spacer Strap
Torsion Tests with Modified Straps
4.0 lb/ft 2.5 lb/ft S-4-4.0 S-2-2.5
Rotation (deg} Torque Bolt 11 A Bolt 11 B11 Torque Bolt 11 A11 Bolt 11 B11
(lb-in} Load Load (lb-in} Load Load ( 1 b} ( 1 b} ( 1 b} (lb}
ao 0 605 912 0 634 765
10° 255 614 960 104 624 770
20° 494 644 1002 199 619 784
30° 707 663 1045 295 605 793
40° 924 678 1102 390 595 798
50° 1195 712 1231 470 590 812
60° 1450 731 1349 550 585 831
70° 1665 731 1444 621 580 846
80° 1928 712 1539 709 575 860
goo 2151 712 1630 813 571 884
55
1200
1000
800
600
400
200
- •--. ' ......_....._
0~--~--,----.--~----~--~--~--~---T--~ 0 200 400 600 800 1000
Applied Torque, (lb- in.)
Figure 33. Applied Torque vs Bolt Load - ?..5 lb/ft Posts.
56
---Bolt ttA"
---Bolt "B"
BOLT •A"
~ / BOLT II B j, ~SIGN POST ~..,.__-....,..~k-::::::" L_ 1 1100111fo('------ 10' ·0" ~
400 800 1200 1600
Applied Torque, ( lb- in.)
2000
Figure 34. Applied Torque vs Bolt Load - 4.0 lb/ft Posts.
57
4.00 1.88 8.62
[ 145 ! I + f i i I I ! I ! I t l u: ::::: :::~ ~ Tl 17.0 .25 •
Figure 35. Basic Retainer-Spacer Strap used with 2.5 lb/ft Eze-Erect System
0 0 • --
• 75 1. 00 4.00 1 ~ 88 8.62
tS [ • 280 i I + + I i I t ~~ ~ ! : ~~ J I I ! I ! l/1' 17.0
.25 ..
Figure 36. Basic Retainer-Spacer Strap used with 4.0 lb/ft Eze-Erect System
N -­. --
/ 34J 11 0/A. X '1 11
l----
_..I,. /,88 II .,l.!l"~,.-l I
p. 7?': i.. t,oo -+----·
----------------------~~~L~5~P~------~==:=~------ I),__ __ __._I
~
~ ..........:
I I I I I
,~
Figure 38. Modified Retainer-Spacer Strap used with 4.0 lb/ft Eze-Erect System
' 1 r 1--+-:---, -A • Ftl
SUMMARY AND CONCLUSIONS
Shown in Table 17 is a summary of the primary results of the static
load tests. Specific conclusions reached as a result of this study are:
{1) Use of 5/16 in., grade 5 bolts in the Eze-Erect system will allow
development of the elastic strength of the 2.5 lb/ft post. They are
of insufficient strength to allow development of the elastic strength
of the 4.0 lb/ft post. (About 61 percent of the post strength can be
developed.)
{2) Use of 5/16 in., grade 8 bolts in the 4.0 lb/ft Eze-Erect system
increases its load carrying capacity, but such bolts are of insuffi­
cient strength to allow full development of the elastic strength of
the 4.0 1 b/ft post. {About 73 percent of the post strength can be
developed.)
(3) As presently configured {the as-tested design) the minimum effective
moment arm in the Eze-Erect splice is 3.1 in. for the 2.5 lb/ft post
and 2.9 in. for the 4.0 lb/ft post. The critical bolt in the splice
is the upper bolt {bolt "A" in Figure 3) during front loading of the
post.
(4) A redesign of the retainer-spacer strap would likely increase the
load carrying capacity of the 4.0 lb/ft Eze-Erect system. This would
be accomplished by increasing the effective moment arm in the splice,
reducing the tensile load in the critical splice bolt. Its capacity
could also be increased by use of larger splice bolts.
{5) Torque on the signpost does not appreciably affect the tensile load
in the Eze-Erect splice bolts or the overall capacity of the posts.
{6) The torsional stiffness of the 2.5 lb/ft and the 4.0 lb/ft post was
determined.
62
Table 17. Summary of Results of Static Tests
Post Size Loading Direction Grade No. of Lowest Maximum Corresponding Lowest Failure Mode (lb/ft) of Bolts Used in Sustained Load Sustained Moment Observedl
Loading the Connection Observed Observed (Fracture) ( 1 b) (lb-ft)
Front 5 185 2235.4 Bolt nAn 2.5 Bending
Rear 5 195 2356.3 Post
Bending Front 5 176.4 2131.5 Bolt nAn 2.5 &
Torsion Rear 5 186.4 2252.3 Post
f ;f
0"1 Front 5 164.7 1990. 1 Bolt nAn w 4.0 Bending
Rear 5 214.7 2594.3 Bolt nan
Bending Front 5 156.5 1891.0 Bolt nAn 4.0 &
Torsion Rear 5 196.5 2374.4 Bolt 11 B11
Front 8 214.7 2594.3 Bolt nAil 4.0 Bending
Rear 8 264.7 3198.5 Bolt 11 B11
Bending Front 8 196.5 2374.4 Bolt 11 An 4.0 &
Torsion Rear 8 246.5 2978.5 Bolt 11 B11
1see Figure 3.
ANALYSIS OF EZE-ERECT SYSTEM
Failure of the Eze-Erect system will be defined as disruption of the
splice between basepost and signpost and/or yielding or fracture of the
signpost or basepost. The purpose of this analysis is to develop a method
whereby the capacity of the Eze-Erect system can be ascertained.
Considering only the post, the elastic moment capacity of the 2.5
lb/ft and the 4.0 lb/ft post is given as:
Me = ay Sxx
Assuming a 145 in. moment arm, the maximum permissible post load, Pm, is
given by
2.5 lb/ft
p = 17,340 = 120 1 b m 145
4.0 lb/ft
p = 33,600 = 232 lb m 145
From the tensile test data presented in Appendix C, the average yield
strength of the 4.0 lb/ft posts was found to be 74,900 psi, while the min-
imum value recorded was 70,000 psi. If these values were used foray, the
65
ultimate post load would be 289 lb on the average and no less than 270 lb.
The static load tests showed the splice capacity was much less than needed
to develop the elastic strength of the 4.0 lb/ft posts.
Analysis of the splice capacity will be accomplished using Figure Al.
Shown are the basepost, retainer-spacer strap, and signpost under the two
directions of loading {front and rear) and the bending load configuration.
For the rear load, the splice transfers the moment developed by the ap­
plied load with a compressive bearing load between the spacer strap and
the basepost, and a tensile load in bolt 11 B11 • The magnitude of this ten­
sile load is termed RBand it is the limiting factor in the splice capac­
ity. When Rs exceeds the ultimate bolt capacity, the tensile bolt breaks
and the assembly collapses. The same principle applies to the splice when
subjected to front loading, except the locations of the tensile and com­
pressive forces are reversed. In this case bolt 11A11 goes into tension and
the compressive bearing load develops around the area near bolt 11 B11 •
To analyze the splice, the following assumptions were made:
{l) The basepost is rigid and does not deform.
(2) The compressive bearing load acts as a triangular distributed load as
shown over the length of contact between the spacer strap and base­
post.
The second assumption is an estimate of the shape of the compressive bear­
ing load as the applied load approaches the capacity of the splice. The
capacity of the sp 1 ice can be found by use of a free-body diagram of the
signpost. Summing moments about Rc for the front load 4.0 lb/ft case
gives
66
0'\ ...._,
Bolt "a• . 1 Bolt "A· Ul-------~~- ,.,3/41--.1 2 11 4 !-111'01(~---
~ _L((((((((( I ~{((((((((((((((((((,,, ....... . \ < ( ( ---< < ( ( ( < < < < ( \ < ( ( (
Bolt 1A1
p = 139.25 + b
For grade 8, 5/16 in. diameter bolts the maximum load Rs is equal to the
area of the bolt times the ultimate tensile stress or
Rs = (0.0522}{15o,ooo)
R8 = 7,830 lb
Based on the geometry of the strap and the assumed compressive load dis-
tribution, the distance "b" was determined to be 3.2 in. Thus, the limit-
ing load, P, as governed by the bolts, is
p = (3.2)(7.830) = 176 lb m 139.25 + 3.2
This load is less than the load needed to develop the elastic strengtff of
the 4.0 lb/ft post (232 lb). Based on tensile tests of a representative
sample of grade 8 bolts (see Appendix E), the average ultimate stress was
found to be 165.57 ksi. This suggests that the average ultimate load for
front loading from the tests should have been about 194 lb. Referring to
Table 7, it can be seen that the average failure load for front loading
was approximately 220 lb. The difference between the predicted and mea­
sured values, which is relatively small, is attributed primarily to the
value of "b" used in the theoretical formula. It is probable that the ac­
tual value is somewhat larger than the 3.2 in. assumed in the theoretical
formula. It must be noted that "b" was shown to increase with increasing
post load. Differences in the assumed bolt ultimate strength and the ac­
tual bolt strengths could have also contributed to the disparity.
The same analysis can be carried out for the 2.5 lb/ft posts, for
different grades of bolts in the connection, and for different directions
68
of load. For rear loading and the load distribution assumptions as shown
in Figure Al, it can be shown that
( 4 )(R8) p = 139.25
Tables Al and A2 compare theoretical with actual test results for the
2.5 lb/ft and 4.0 lb/ft systems. S~nce the signposts were loaded in in­
crements of 10 lb, the maximum load was taken as the last sustained load
the assembly was able to resist before the next 10 lb increment was added
that caused failure. The failure load was therefore within 10 lb of the
maximum load observed.
In reviewing the results given in Tables Al and A2, it can be seen
that reasonably close correlation was achieved between predicted failure
loads and measured failure loads, at least when failure occurred in the
splice. Differences that did exist can be attributed to the factors de­
lineated in preceding paragraphs. It must be noted also that these formu­
las predict splice bolt loads and limits thereto. Prediction of failure
in the post, i.e., post fracture, is somewhat more difficult and really
not necessary. In most cases (e.g., AASHTO Specifications), the maximum
load permitted on the post is that which initiates yielding in the post.
The results of Tables Al and A2 also indicate that an effective mo-
ment arm, "b", of approximately 3.2 in. for front loads and 4.0 in. for
rear loads is reasonably accurate. This observation is also supported by
the results of the instrumented bolt tests.
Tests were also conducted to evaluate the effect of a torsion load
combined with a bending load. This involved offsetting the applied load
from the centroid of the signpost 5.4 in. for the 4.0 lb/ft post and 4.5
in. for the 2.5 lb/ft post. In this case, the behavior of the connection
69
Table Al. Comparison of Predicted Failure Loads with Test Results, Bending Load, 2.5 lb/ft Posts
Post Size and Load Direction
Grade No. of Bolts Used in Splice
Bolt Guranteed Minimum Ultimate Load
{ 1 b)
{ 1 b)
{1 b)
{ 1 b)
1 Post fractured.
2.5 Front Load
5
6260
6890
180
198
Table A2. Comparison of Predicted Failure Loads with Test Results, Bending Load, 4.0 lb/ft Posts
Post Size and Load Direction
Grade No. of Bolts Used in Splice
Bolt Guranteed Minimum Ultimate Load
{ lb}
{ 1 b)
( 1 b)
( 1 b)
Actual Average Fa i 1 ure Load from Tests (lb)
4.0 Front Load
8
7830
8820
225
253
265
is much more difficult to analyze. The induced torque can be transferred
from the signpost to the basepost in three basic ways as shown in Figure
A2. In case 1 the torque is transferred through the spacer strap and does
not add extra load to the tensile bolt. In case 2, the torque is trans­
ferred by shearing forces in the splice bolts corrmon to the basepost and
signpost, while case 3 shows the torque transferred by bearing between the
two posts and a tensile force in the common splice bolts. Comparison of
the maximum loads for both sizes of posts due to bending and bending and
torsion loads are shown in Table A3. The additional torsion load when
superimposed on the bending load reduces the average maximum post load by
approximately 8 percent, depending on the size of the post and direction
of loading.
Tests were run to determine the magnitude of the load developed in
the tensile bolt during bending and torsion loading for the 4.0 lb/ft
posts with front and rear loading directions. The purpose of these tests
was to determine to the extent possible the load transfer mechanism for
torque on the post. Shown in Table A4 are results which compare the aver­
age bolt loads for the bending and torsion loading with the bending load­
ing, and the bolt load due to torsion transfer. The results tend to sug­
gest that torsion transfer occurs by a combination of all three methods,
making analysis difficult. The significance of the method of torsion
transfer is not important where the post, and not the connection, is the
limiting strength factor.
This can be shown by analyzing the 2.5 lb/ft post under bending load
from the rear direction. Tests for this case showed that the failures oc­
curred in the posts and not the connection. The state of stress in an el­
ement along the tensile face of the post at the fixed connection (ignoring
72
......, w
CASE I CASE 2 CASE 3
Figure A2. Transfer of Torque from Signpost to Basepost by the Connection.
Table A3. Comparison of Bending Maximum Loads with Bending and Torsion Maximum Loads for 2.5 lb/ft and 4.0 1b/ft Posts
Post Load Grade No. of Bolts Avg. Max. Load Range of Avg. Max. Loads Range of Size Direction Used in Connection 11 Bending 11 Max. Loads 11 Bending & Torsion 11 Max. Loads
( 1 b) 11 Bending 11 ( 1 b) 11 Bending & Torsion 11
( 1 b) ( 1 b) - 185
2.5 lb/ft Front 5 188 185 176 176 195
195 196 2.5 lb/ft Rear 5 205 215 193 196
205 186
-....! 165 177 ~
4.0 lb/ft Front 5 172 175 170 177 175 157
215 217 4.0 lb/ft Rear 5 225 225 207 207
235 197
225 197 4.0 lb/ft Front 8 222 225 207 207
215 217
265 257 4.0 lb/ft Rear 8 265 2.65 254 257
265 247
Moment Arm = 145 in.
Table A4. Comparison of Average Bolt Loads for Bending and Bending and Torsion Loading (4.0 lb/ft Posts)
Erect Load Rear Load 11 Bending 11 11 Bending and Torsion .. 11 Bending 11 11 Bending and Torsion .. Predicted 1 Bolt Load Bolt Load Bolt Load Bolt load Increase
( 1 b) ( 1 b) ( 1 b) ( 1 b) (1 b)
1827 1804 1309 1215 139
2301 2213 1609 1499 193
2771 2648 1910 1841 247
3241 3120 2217 2080 301
""-' 3706 3625 2526 2376 355 (J1
2840 2714 409
3168 3065 463
3501 3431 517
1. Using the 4.0 lb/ft posts the distance between the resisting couple is approximately lin. The increased bolt load is then equal to the (eccentric load) x 5.4 in./in.
**Note: All bolt Loads are adjusted for initial preload.**
2.5 lb/ft Post
76
f 4.511
era. = 501.7 P psi
TT : 114.5 P psi
the bolt holes and other stress raisers) is shown in Figure A3. The mag­
nitude of this stress is equivalent to the moment in the post divided by
the section modulus. The theoretical load that initiates yielding in
the post was shown to be 120 lb, i.e., Py = 120 lb.
Py is the load at which the outer tensile fiber of steel first
reaches the minimum guaranteed yielastress of 60,000 psi. For a unixial­
ly loaded tensile specimen the maximum shearing stress equals one-half the
measured tensile stress. Failure is assumed to occur when the maximum
shearing stress exceeds the shearing yield stress at any point in the
structure. This is consistent with the maximum shear stress theory of
failure. Under the bending load, the element analyzed is essentially a
uniaxal tensile specim~n.
The same element under combined bending and torsion loads is shown in
Figure A4. The bending stress remains the same as in the previous exam­
ple. The shearing stress due to torsion can be found by the equation for t
an open section TT = El/Jmt3-, where T equals the applied torque, and the
denominator represents the summation of the length times the thickness
squared of the discrete rectangular elements that make up the cross sec­
tion of the shape divided by 3. For the 2.5 lb/ft post
Therefore
El/3mt2 = .0393 in.3
TT = 114.5P psi
as= 501.7P psi
The ratio of bending stress to shear stress will be 501.7P/114.5P = 4.38.
Using the maximum shear stress theory the load at which yield first occurs
77
Tyield = 60,000 psi/2 = 30,000 psi
PY = 108.7 lb at first yield
The ratio of the yield load in bending to the yield load in bending and
torsion is 1.10, pointing to an expected loss in capacity of 10 percent.
For the 2.5 lb/ft posts, the actual ratio of maximum bending load to maxi­
mum bending and torsion load was 1.062, or 6 percent loss in capacity.
The analysis presented is conservative (overstates torsion} because it as-
sumes the torque arm 11e'' remains constant. In reality, the torque arm is
decreased by rotation of the signpost, giving a smaller shearing stress
combined with flexural stress.
For the signpost assembly that fails in the splice, the tests show
the reduction in capacity due to bending and torsion to be of the same
magnitude as that for post failure. One can expect the same failure modes
to apply for corresponding bending and bending and torsion tests. If the
assembly is designed to fail in the post under bending load, then it will
also fail in the post under bending and torsion at a reduced load.
This same type of analysis can be conducted on the 4.0 lb/ft posts,
assuming the splice would be able to develop the capacity of the posts.
The value for the shear stress due to torsion in terms of Pis 64.26P psi,
while the normal stress on the element due to flexure is 258.9P psi. The
78
The ratio of bending stress to torsion stress is 4.02, giving an expected
capacity ratio of failure load in bending to failure load in bending and
torsion of 1.12, or 12 percent reduction in capacity. This would be ~
conservative estimate of the ultimate load under bending and torsion.
Although the ability to conservatively determine an ultimate load for
the assembly has been demonstrated, some question has been raised on the
behavior of the posts at ultimate load. The tests have indicated the
posts will fracture when sufficiently rear loaded. This is due to the
tensile stress being induced on the area of the post where the holes are
punched, with resulting stress concentrations. For the front 1 oad case,
no stress raisers will be found on the tensile side, and significant
yielding will occur (as evidenced by the tensile test on the material)
before the ultimate stress is reached at any point. The implication is
that buckling will be the failure mode for front load as the yielding
causes loss of shape under static loading.
79
80
COMPARISON OF THEORETICAL DEFLECTIONS AND ROTATIONS WITH EXPERIMENTAL RESULTS
Castigliano's Theorem was the basic method used in determining an ex­
pression for deflection due to bending, while torsional rotations were
developed using the method found in reference 5.
The basic model for deflections is shown in Figure Bl. Because of
the long slender nature of the structure, deflections will be assumed to
be caused by bending only, ignoring all other contributions. Also, the
section of overlap between basepost and signpost {B-C) will be approximat­
ed as having twice the moment of inertia of an individual section. The
deflection equation is as follows:
- 1 (L 6A - rr ~ oM
M cfP dL
- 1 fl38 1 15.5 b.A -IT {Px){x}dx + 2ET P{x + 138)dx 0 0
1 11.5 + IT P(x + 143.5)(x + 143.5)dx 0
After integrating and collecting terms, the deflection is
p !!.A = .0325 y (Pin lb; I in in. 4)
This equation is applicable for both sizes of posts. A further refinement
can be made using the reduced moment of inertia (I'xx) by considering the
holes in the posts.
-c I: 10
.f..) 1+- ......... ..c .....
I'xx = Ixx- Ad2
The moment of inertia of the area removed is found by the transfer axis
theorem where 11A11 is the area removed and 11 d11 is the distance from the
centroid of this area to the 'x-x' axis of the section.
For the 2.5 lb/ft posts - Ixx = .203 in.4
I' -XX - .233 in.4
I' -XX - .448 in.4
The deflections are tabulated in Tables 81 and 82 for the two sizes of
posts, and include the average values found from the bending tests. These
values are then plotted in Figures 82 and 83 for comparison.
The theoretical deflections tend to be less than the actual average
deflections. This is especially true for the 4.0 lb/ft posts. The dif-
ference is caused by the action of the sp 1 ice between the basepost and
signpost. The 2.5 lb/ft posts nest together closer than the 4.0 lb/ft
posts. In addition to bearing directly against the spacer strap, the 2.5
lb/ft posts bear directly against each other, while the 4.0 lb/ft posts
tend to bear against the spacer strap only. Referring back to Figure Al,
the applied moment is resisted by a tensile force in one of the connection
bolts and a compressive force between the signpost and spacer strap. The
magnitude of this compressive force will be the same as the force devel-
oped in the bolts, about 6,000 to 8,000 lb at ultimate load, depending on
the grade of bolts used in the connnection. This is sufficient to cause
flattening of the spacer strap in the connection which has been observed
in the testing.
83
Table Bl. Theoretical and Average Actual Deflections for 2.5 lb/ft Posts
Load Theoretical Deflections Average Actual Deflections (1 b}
Ful1-Section Reduced Section Fl"ont Load Rear Load (in) (in) (in) (in}
19.3 2.7 3.1 4.6 3.0
45 6.3 7.2 8.8 7.3
55 7.7 8.8 10.6 9.0
65 9.1 10.4 12.2 10.8
75 10.1 12.0 14.2 12.6
85 11.9 13.6 16.0 14.5
95 13.3 15.2 18.0 16.1
105 14.6 16.3 19.9 17.8
115 16.0 18.4 21.9 19.8
125 17.4 20.0 23.8 21.4
135 18.8 21.6 25.7 23.4
1~-5 20.2 23.2 27.6 25.3
155 21.6 24.8 29.7 27.3
165 23~0 26.4 31.9 29.2
175 24.4 28.0 34.3 31.2
185 25.8 29.6 37.0 33.9
195 27.2 31.2 38.5 36.8
205 28.6 32.8 39.2 .
Table B2. Theoretical and Average Deflections for 4.0 lb/ft Posts
Load Theoretical Deflections Average Actual Deflections (lb)
Reduced S:ection Full-Section Front Load Rear Load (in) (in) (in) (in)
29 1.9 2.1 4.5 .9
55 3.6 4.0 6.6 3.2
65 4.2 4.7 7.7 4.2
75 4.9 5.4 8.8 5.1
85 5.5 6.2 9.9 6.2
95 6.2 6.9 11.0 7.2
105 6.8 7.6 12.2 8.4
115 7.5 8.3 13.4 9.6
125 8.1 9.1 14.7 10.8
135 8.8 9.8 15.9 12.2
145 9.4 10.5 17.3 13.5
155 10.1 11.2 18.7 14.7
165 10.7 12.0 20.2 15.8
175 11.4 12.7 22.7 16.8
185 12.0 13.4 18.0
205 14.9 14.3 20.5
--G co 0 en
40 60 80 100 120 Load (I bs)
140 160
Figure B2. Load vs Deflection - Comparison of Actual and Theoretical Results, 2.5 lb/ft Posts.
180 200
co 0 ""-1
32
24
16
J#/
/It" /
Load, { lbs)
Figure B3. Load vs Deflection - Comparison of Actual and Theoretical Results, 4.0 lb/ft Posts.
180 200
Looking at the 4.0 lb/ft posts, the additional deflection due to
flattening of the spacer strap can be estimated by the use of similar tri­
angles.
Mnd = 40 6strap
6end = 27 6strap
For front load, an additional 1 in. of deflection at the end of the post
would require only .025 in. of settlement in the connection. Likewise,
.037in. of settlement would be needed in the connection to cause an aadi-
tional 1 in. of deflection under rear load. This is consistent with the
actual results obtained from the static tests.
The theoretical rotations due to torsion can be developed in a simi-
lar manner. The equation for rotation of a thin-walled open section is
given as:
a = TL G Jeq.
where a is the rotation in radians, T is the applied torque in lb/in., L
is the length subjected to the torsion load, G is the modulus of rigidity,
and Jeq. is the torsion constant in in.4, taken as:
where "m 11 and "t" are the length and thickness of the discrete rectangular
elements that make up the cross section of the shape. For the 4.0 lb/ft
posts Jeq was taken as .01778 in.4 and for the 2.5 lb/ft posts Jeq was
88
found to be .00499 in. 4. The length was 10 ft for all tests conducted.
The modulus of rigidity for steel is between 10 and 12 million psi. The
equations can then be written as follows, changing the angle nan to de­
grees instead of radians.
2.5 lb/ft posts: G = 10 X 106 ~si a = • 1378T deg
G = 12 X 106 psi e = .ll48T deg
4.0 lb/ft posts: G = 10 X 106 psi e = .03867T deg
G = 12 X 106 psi e = .03222T deg
Figures 84 and BS compare the theoretical deflections with the values de­
termined by torsion tests. The average values were determined by a linear
regression of the data. Good agreement between the data and theory is
shown in both cases.
I I m =8.7108 lb-in.,
deg
m = 7.2569 Jb- in;~ deQ 8 =0.1378 T
10 20 30 40 50 60 70 80 90 100
Angle of Rotation, 9(de;rees}
Figure 84. Angle of Rotation vs. Torque - Comparison of Theoretical with Actual Results, 2.5 lb/ft Posts.
90
2000
1750
1500
1250
- .5
I
500
250
THEORY WITH G = 12 x 108 psi ----w m = 31.0~!59 lb· in.fdeQ
8 = 0.03222 T
THEORY WITH G = 10 x I08 psi m = 2!5.8598 lb- in.fdeg
8 = 0.03867 T
r = 0. 9993849
10 20 30 40 50 60 70 80 90 100
Anqle of Rotation, 8 (degrees)
Figure 85. Angle of Rotation vs Torque - Comparison of Theoretical with Actual Results, 4.0 lb/ft Posts.
91
92
ID NO. Yield Strength (psi)
Tensile Strength (psi)
S-1-2.5 86700 151800 S-2-2.5 87200 153100 S-3-2.5 77200 136900 S-4-2.5 87800 156.400
S-5-2.5 90100 149100 S-6-2.5 88600 156300 S-7-2.5 75200 135600 S-8-2.5 79700 139400 S-9-2.5 78100 138500
S-10-2.5 79100 139000 S-11-2.5 68100 125400 S-12-2.5 77800 138400 S-13-2.5 80000 140800 S-14-2.5 88400 153700
Average Yield Strength = 81700 psi Average Tensile Strength = 143900 psi
1These tests were conducted by Pittsburgh Testing Laboratory for Franklin Steel Company.
93
ID NO. Yield Strength Tensile Strength (psi) (psi)
S-1-4.0 73100 133000 S-2-4.0 74700 136600 S-3-4.0 73300 132600 S-4-4.0 76200 136900 S-5-4.0 79800 142600 S-6 ... 4.0 70000 130600 S-7-4.0 70200 130800 S-8-4.0 75700 137400 S-9-4.0 70300 134900
S-10-4.0 72700 138400 S-11-4.0 77900 137700 S-12-4.0 74300 134300 S-13-4.0 77600 133700 S-14.4.0 83100 144300
Average Yield Strength = 74900 psi Average Tensile Strength = 136000 psi
1These tests were conducted by Pittsburgh Testing Laboratory for Franklin Steel Company.
94
95
Stress Maximum Tensile Sample Area Load Strength Fracture
Identification {in. 2) {1 b) {psi) Location
1 0.0522 7,060 135,200 in threads
2 II 7,000 134 '1 00 II II
3 II 6,960 133,300 II II
4 II 6,540 125,300 II II
5 II 6,800 130,200 II II
6 II 6,900 132,200 II II
7 II 6,860 131,400 II II
8 II 6,780 129,900 II II
9 II 6,960 133,300 II II
10 II 7,020 134,500 II II
Average tensile strength= 131,950 psi
lThese tests were conducted by Pittsbugh Testing Laboratory for Franklin Steel Company.
96
97
Stress Maximum Tensile Sample Are~ Load Strength Fracture
Identification (in. ) ( 1 b) (psi) Location
1 0.0522 8,670 166,100 in threads
2 II 8,640 165,500 II II
3 II 8,730 167,200 II II
4 II 8,630 165,300 II II
5 II 8,650 165 J 700 II II
6 II 8,710 166,900 II II
7 II 8,540 163,600 II II
8 II 8,690 166,500 II II
9 II 8,550 163,800 II II
10 II 8,620 165,100 II II
Average tensile strength = 165,570 psi
lThese tests were conducted by Pittsbugh Testing Laboratory for Franklin Steel Company.
REFERENCES
1. Effenberger, J. J. and Ross, H. E., Jr., "Report on the Static and Dynamic Testing of Franklin•s U-Post and Eze-Erect Connection," Research Report 3491-1 F, Texas Transportat 1 on Institute, Texas A&M University, June 1977.
2. Ross, Hayes E., Jr., and Walker, Kenneth, 11 Static and Dynamic Testing of Franklin Steel Signposts, .. Research Report 3636, Texas Transporta­ tion Institute, Texas A&M Univ.e.rsity, February 1978.
3. 11Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals, .. AASHTO Subconvnittee on Bridges and Structures {1975).
4. Strainsert Corporation, Union Hill Industrial Park, West Conshohocken, Pa. 19428.
5. Timoshenko, S. and Goodier, J. N., Theory of Elasticity, Second Edition, McGraw-Hill Book Company, 1951.
99