View metadata, citation and similar papers at core.ac.uk
brought to you by
CORE
provided by Lehigh University: Lehigh Preserve
Lehigh University
Lehigh Preserve
Fritz Laboratory Reports
Civil and Environmental Engineering
1964
High strength bolting in the U.S.A., August 1964,
Reprint 275
J.W. Fisher
L. S. Beedle
Follow this and additional works at: http://preserve.lehigh.edu/engr-civil-environmental-fritz-labreports
Recommended Citation
Fisher, J.W. and Beedle, L. S., "High strength bolting in the U.S.A., August 1964, Reprint 275" (1964). Fritz Laboratory Reports. Paper
163.
http://preserve.lehigh.edu/engr-civil-environmental-fritz-lab-reports/163
This Technical Report is brought to you for free and open access by the Civil and Environmental Engineering at Lehigh Preserve. It has been accepted
for inclusion in Fritz Laboratory Reports by an authorized administrator of Lehigh Preserve. For more information, please contact
preserve@lehigh.edu.
Large Bolted Connections
by
"John W. Fisher
Lynn S. Beedle
CONTRIBUTION TO THEME lIb:
HIGH STRENGTH BOLTING IN THEUoSoA o
by
John Wo Fisher, Research Assistant Professor
of Civil Engineering,Lehigh' University
Bethlehem, Pennsylvania, and
Lynn S.Beedle, Research Professor of Civil Engineering,
Lehigh University, Bethlehem, Pennsylvania
DESIGN CONCEPTS IN THE U9 SQA Q
The original application of
~.SoAo
~igh-strength
was based upon friction-type joints only.
A325 bolts in the
The first specifica-
tion in 1951 merely permitted the substitution of a like number of
bolts for hot-driven rivets(l)o
It is well known that friction-type joints are dependent on
proper bolt tension and an adequate coefficient of frictlono
In the
UoSoA o the faying surfaces are usually only clean mill scale, and
numerous tests of A7 stee 1 Joints have indicated that a slip coeffi.cient
of 0035 is representative of values encountered in actual construction.
Because of higher labor costs in the UoS.Ao it 18 considered uneconomical to increase tpa slip coefficient by treating the faytngsurfacese
Generally it is less expensive to use a larger joint with more bolts.
the recent introduction of the higher strength AA90 bolt(2) will allow
the use of smaller joints because of higher clamping force per bolt;
thus it can be expected that there will be even less of a tendency to make
use of special faying surface treatments.
288.22
-2-
The concept of a bearina-type conneetionw81flrstlntroduced
when the specification was revised in 19.54.
At that time,the omission
of palntwas required ·to apply only to Ja,tnts subJected· to stress rever . .
•
.:."
>
sal or vlbration,or where joint . sllppalewou,1c1 beuncleslrable
0
Tests
conducted at the University of Washingtonh.d sbQwn, thatpaintlna the
faylngsurfaees8ubstanti.ally, reclucedt,he slipcoefflctent
o
••••
".
•
•
•
•••••
'
•••••••
'• • • • •"
•••••••
'
• •
,"
••••
'• • • • • • • • • • • • • • • • • • • • • • • •
(3)
.' . I t "8S
recognlz.d tbat many jolnts were'e r ecce:<I,ln bea'tioa 'ndthat slipP',ge
was not a'problettto
into beart'hg
Movement althe conn.ecteclpart,. brlnI1ns··the bolts
a8~in8ttheslcle8ofthebol.8~a.
t'othestren:gth or sbape of tne8truetUr'e6
'1naowaydetrtmental
Allo,thecc>,.t ofle.vins
I,ft the 1960 revision of the a,eclflb.fiIt 1011 of the Research
Counci.l onliveted and Bolte'd Structural Joiri.ts selear 4tstinetiotl
this time the greater sbear. streoICh·..,of· .the blllliliJl,tlie,qtb ·b,(),lt··.w8s
not recognized.
planes.
In 1960, the stresses u.e4: to proportlonbeari.ng-type-
Thus) the allowable stresses
u",d
in ,ft.lctton-typeJof.nts
reflect the abl1ityof' the jolnttore'18tllil.pwhet."lJtbilvalues
for the bearing-type joint reflecttb.,.h••riqltrllft8':tb of the bolt.
type joints correspo<nd to a factor. of safety alainst Ilip of, 104·0
under grayity and live 108480
It is recQgnlzed that the bolts are
not actually stressed in shear nor 18 bear,inS a eQn8ideratlonin frlc-
tion-type connection8 o
However, "It is conventeotto specify an allow-
able "shear'stres. 1n ordertbatproportionlns of friction-type co;nnectiona may be carried, out usinlth.s&mewell-eeta..,lllbed methods
as
areuBed In the del:lsn of rlvetedjolnt8q
A'llo".b1e stresse. for tiearlftl-type con••etloR8 are b•••clon
the ultimate.h••r ",Ct:enltb of thef•• tlllClr.Jla.eo.:lvetelt.ofllJ:lt
A7 and .l\440.lt881 JalAli have .hown that'tbe faetor,of •• fety ".ri••
from about 303 for'hort connection. eleva to 202 for Joints up to
.50 inches long (4)(.5
>.
In bearins-typedointe ,even thougb the bolt.
are tightened so'thatfrlctlonmay ,earl", tbe WOrking load. frict10nal
resistance 1s not requlredandthe deslgnls 'properly based on th.
shearing strenathofthe bolts.
1 'P'lltlIYe. T.'~.'.()f. JO~Qt, 'Co~n.<;~.4bYA3~5Io1t
•..·wltbOQt.W... btra
0
Durinl the'pastfew year•• number of fatlgue·te8ts on bolted
lap spU.ees we.re. conducted at tbe. Unive.rl1ty of tlHnots (6).
Theee
tests tl'lcludedspecirnensde818ned for extreme conditions:
overliled
holes"no washers. and inmostc8ses, minimum clampini
employed.
When the
turn~of-nutmetbodwa8 used
w~s
to preload the bolt' none bf,the
specimens faUe.duntil at least 2.4 x 1Q6 ..._ •• we..e applied at a
0-30 kai stress cycle o
This was true even tboulh .nuDtber 0·£ the
specimens slipped into bearing during the flr8t cycle of loading.
-4-
One specimen with no washers and oversized holes (1/8-ino
instead of 1/16-in.)s11pped into bearlol during the first cycle of
loading and ran 3 x 10
6
cycles at 0 to 30 kll without failure.
Rel.xation teats tooetarmine 101. of clamping force tilth
time were also conducted by the University of:nll11noll on blab-tler.oatb
bolts (6)
There wa. no differen.e·e 1n bolt load for boltIiJ with 1/16-1n.
0
overslzeholes. whether ·or not a wa.herwa. URoer' tb.e·bolt he.do
when no washers were u8ed.
during the first d·.yo
Tbe
Molt olthi'• •utlll loslaenerally occurred.
:Measurement on boltl Cllntened by the turn-of..
nut method in test joints agreed with the.e special relaxation tesu(5).
Even after 10 months, elongation measurements indicated no signif:Lcant
addit"ional relaxatton other than whatoe,eurred l1X1tled.1ately .ftertbe
initial tightening o
As a· result of thesestudies,washerB are no lonler required
under the turned element when A325 bolt•••re installed by the turn-of-
nut method.
They are used
under ·the turned a lame n.t to minimize iriteau-
larities in the torque-tension relationship When bolts are tightened by
the calibrated wrench method o
The use of washers' in the U.S.Aopra.ct:Lce 1s specified in
order to provide a non-galling surface under thepat:tturned in
ti.abteft~
ing as tests have shown they only play a minor role in distributing
pressure due to bolt tensiono
,-5-
288.22
3. Static Testa of A7 .oct ~44Q$tt'.1 JQlrtt'
Numerous tests of connections of structural carbon steel
connected by high-strength bolts have indicated that for clean mill
scale a slip coefficient of 0.35 is repre.-entative (3) (4) (5) (7) •
Neither length norwldth was found to appreciably affect the slip
resiStance (5).
Reference 8 reported similar reau1ts.
Tests at Lehigh University on A440 hi-p-strength steel connec-
ted by 1\325 high-strength bolt. showed a slllht deere.le in the mean
slip coefficient (10).
More recently. tests of A440 neel connecU.ona
connected with the biaher-strength A49'O bolt have given a 811pcoefflThe te,.ta are too
cient sl18ht1y h·igher than that reported in Itef. 100
few to give conclusive results; however, the indication 1s that
th~
higher clamping force of the A490bolt .y. improve the slip coef,ficient
0
A few constructional alloy steel joints connected by A325 orA490 bolts
were also tested at Lehigh and have yielded similar resultso
Recently. theoretical solution w.Re developed for the unequal
distribution of load among the bolts in double-lap tension spl:lceswhlch
have non-linear behavior(ll).
Analytical studies supported by tests
have shown that an increase in net plate area increases the .'verale
shear strength of the fasteners in the lon,aer jo:lnts
:- summarizes the analytical and experlmentalfindings
40 Joint
~ovement~:l.n
0
Figure 1
0
II Railroad Bridge
During the BUDmer of 19598n inveitigation was undertaken in
conjunction with the through-truss bridge for the Michigan Central
Railroad near Chicago, Il11nois.
A cooperative investigation by the
288.22
-6-
Association of American Railroads Research Laboratory and the University
of Ililnois was initiated at the time of fabricatlon o
Initial readings
were taken in the fabrication yard durlngfinal assembly and reaminlo
Additional readings were taken after erectioft and at periodic intervals
thereafter.
The readinll were taken at all joints of'one trus80
The
bolts were installed by the turn-af-nut method.
\
Reference 12 presents the results of the measurements which
were conducted over a J-,!-year ,eriod o
In aeneral. this study has shown
that little 1f any chanse has occurred in the structure
Duringerec-
0
tion, movements up to 1/16-1n. were noted '1n randomdirectioRs.
Joint
movements measured over 3 years ofd:ervice averased only Oo002-ino and
were so small that experimental techniques could have caused the varia...
t1on o
No significant change in camber has oecurred o
The erection
movements were random in direction and magnitude and did not always
coincide with the direction of dead load Stre.ss:lng (12)
0
5. Tests of Bolted Steel Moment Connections
Three identical beam spli.ces with lap connections .were tested
in a project at Corne 11 Uni versity (13) •
The bolts were designed on the
'basis of 22 kai shear stress as permitted In.bearing-type connections o
None of the connections slipped belOW the working loadP
w
the connections developed the full plastic
~ment
and all of
of the gross section
and showed satisfactory deformation characteristics.
A similar test
at Cambridge University with the bolts desianed for 30 ksi shear stress
also developed the full plastic moment(14).
-7-
288 22
0
INSTALLATION QF HIGH-STRENGTH BOLTS
Early Uo So specifications stated the well-known formula
relating torque to bolt tension and listed a table of torque-tension
values(l).
However, a number of later studies indicated that such re-
lationships are unreliable because of theare4t variability of thread
condition, surface conditions under tbe Rut, lubrication an" other
factors that use up tbe torque enera, without :Ln4uclnltens1.on in the
bolto
Studies at NOJ:thwesteJ:n UniveJ:sUy in 1946(1.5) and at the
.
.
..
.
(16)
.
University of M1sIourlln 1955 . . have s:hotfllth.t thest4nd.r:d devia-
tion of torque was about 15'10
Bolt tension baaed' on applied torque
could vary as much 8£1 ±30% from the averase of ,8sroup
as shown in Fig. 2 ( 16)
by Me 81 rs
0
0
of8i~lar
bolts
This i8 cofts14eJ:ably above the .s'l. mentioned
Tomonaga and Ta j ima (8).
The 1.5'1. va lue :is can.idered to be
realistic for installation conditions in. the UoSo
The torque re18>tion-
ship becomes especially erratic when bolts are tiahtened into the 10elastic range and the threads begin to
def~rmo
In addition, installa-
tion costs are hlgh for the torque wrench method of installation and
with the large diameter A325 boltsanel the new A490 bolt considerable
torque is required to pr,eload the bolt
0
Two methods of controlling bolt tension are recommended by
the Research Council - the calibrated wrench and the turn-af-nut method o
The calibrated wrench method is essentially a torque control and success
depends on using a hardened washer under the nut in order to limit the
variation of friction between the underside of the nut and the gripped
288.22
material o
-8-
The wrench 1s usually calibrated in
8
hydraulic calibrator
as shown 1n F1go 3.
A number of factors led to the turn-of-nut methodo
As noted
earlier, tests have indicated that 'bolts suffer no injury when tightened
into their inelastic region o
Secondly, bolta actually were being
tightened far above their proof load due to faulty torque wrench inspection without any noticeable ill effect.
The tUl'n-of-nut method utilizes a strain control 8<nd there-
fore 18 ideally suited to controlling tightenina in the inelastic ranl80
The procedures currently in use have shown that a uniform tension 1s
achieved because relatively large variations 1n bolt elongations cause
only minor variations in tenslon aince the load-elonaatlon curve is
reasonably flat(17).
Numerous tests Includina those summarized by Dr o Thurlimann 1n
the Final Report of 6th Congress (18) have shown that the inelastically
loaded bolts have performed wallo
In fact, har4ened washers were once
required under both the head and nut of A325 bolts ,in order to provide
a consistent torque relation, to prevent galling of the structural
material and to prevent bolt,relaxation o
Tests have now shown that the
washer is not needed for the last two reasons and since the turn-ofnut is a strain control rather than a torque control, no washers at all
are required when this method of tightening 1s used for A325 bo1ts(2)
0
-9-
SUMMARY
Current design concepts in the UoS. are discus.ed o Two types
of connections are used: friction-type and bearing-typeo
The friction-
type connection reflects the ability of the Joint to resist sllp whereas
the bearing-type connection reflects the ultimate strength of the jolnto
Experience with bolted connection 1n the laboratory and in the field is
summarized
0
Finally, the factors which have led to currently used in-
stallation procedures are discussedo
-10-
REFERENCES
1.
Research Council on Riveted and Bolted Structural Joints of the
Engineering Foundation
SPECIFICATIONS FOR THE ASSEMBLY OF STRUCTURAL JOINTS USING
HIGH-STRENGTH STEEL BOLTS, 1951
2.
Research Council on Riveted and Bolted Structural Joints of the
Engineering Foundation
SPECIFICATIONS FOR STRUCTURAL JOINTS USING ASTM A325 or
A490 BOLTS, March 1964
30
Vasarhelyi, Do Do, Beano, So Yo, Madison, R. Bo, Lu, Zo Act and
Vasishth, U. Co
EFFECTS OF FABRICATION TECHNIQUES, Transactions ASCR, Vol.
126, Part II, 1961, pp. 764-796
4e
Foreman, Ro To, and Rumpf, J Lo
STATIC TENSION TESTS OF COMPACT BOLTED JOINTS, Transactions,
ASeE, Volo 126, Part II, 1961, PPo 228-254
5.
Bendigo, Ro A., Hansen, Ro A., and Rumpf, J. Lo
LONG BOLTED JOINTS, Journal of the Structural Division, ASCE,
Volo 89, Noo 8T6, December 1963
60
Chesson, Eo, Jr. and Munse, Wo H.
STUDIES OF THE BEHAVIOR OF HIGH-STRENGTH BOLTS AND BOLTED
JOINTS, University of Illinois, Engineering Experiment
Station, Bulletin 469, 1964
70
Hechtman, Ro Ao , Young, Do Ro, Chin, Ao Go, and Savikko, Eo Ro
SLIP OF JOINTS UNDER STATIC LOADS, Transactions, ASeE,
Volo 1'20, 1955, ppo 1335-1352
8.
Tomonag8, Ka, and Tajima, Jo
THE USE OF HIGH-STRENGTH BOLTED JOINTS IN RAILWAY BRIDGES,
Preliminary Publications, 7th Congress lABSE, 1964, PPo
0
379-385
90
Carpentier, L., and Alemany, B.
EXPERIENCE FRANCAISE DES BOlLONS A HAUTE RESISTANCE,
Preliminary Publications, 7th Congress lABSE, 1964,
ppo 397-405
10.
Fisher, Jo Wo, Ramseier, P. 00' and Beedle, Lo S.
STRENGTH OF A440 STEEL JOINTS FASTENED WITH A325 BOLTS,
Publications, IABSE, Volo 23, 1963, pp. 135-158
288 22
-11-
0
lIe
Fisher, Jo We' and Rumpf, Jo Lo
THE ANALYSIS OF BOLTED BUTT JOINTS, Fritz Engineering
Laboratory Report Noo 288.17, Lehigh University,
Bethlehem, Pa., 1964
120
Chesson, Eo, Jr.
JOINT BEHAVIOR OF A BOLTED RAIUlAY BRIDGE DURING ERECTION
AND SERVICE, SRS No o 284, University of Illinois, Urbana,
I111nois, 1964
130
Douty, Ro To, and McGuire, W.
HIGH-STRENGTH BOLTED CONNECTIONS WITH APPLICATIONS TO
PLASTIC DESIGN, Preliminary Publications, 7th Congress,
IABSE, 1964, PPo 565-576
140
Johnson, Lo G., Cannon, Jo Co, and Spooner, Lo Ae
HIGH TENSILE PRELOADED JOINTS, British Welding Journal,
September 1960, po 560
15
Maney, Go Ao
0
WHAT HAPPENS WHEN A BOLT IS TWISTED OFF?, Fasteners, Vol.
3, Noo 4, 1946
160
'auw, A o
)
and Howard~ L. Lo
TENSION CONTROL FOR HIGH-STRENGTH STRUCTURAL BOLTS, Proceedings, AISC, 1955, pp. 13-21
178
Rumpf, J o Lo, and Fisher, Jo Wo
CALIBRATION OF A325 BOLTS, Journal of the Structural Division, ASeE, Vol. 89, Noo 8T6, Decembe'r 1963', pp. 215-234
180
Thurlimann, Bo
RESEARCH ON lARGE COMPACT JOINTS WITH HIGH STRENGTH STEEL
BOLTS, Final Report 6th Congress IABSE, 1960, ppo 191-201
8~_
i
Single Bolt
/
SfJngle Dolt
(II tot)
--- ..j'/....... -- -
(8U l,ot)
-. -- -- -- -
--
--
60t-
o
Plate Failure
Uoundory
H
t2
~
::D
tj
z
~
I
!td-~
~
Test Points
~
o An/As
tI)
«
~
V)
rAJ
~
~
«
~
• An/As
:::
..
0.8
1.0
t
+ An fA 8 • 1.2
2 -
I.
in. grip
20
..
I in. grip
40
60
80
JOltrr LENGTII, INCIIES
Fip;urc 1.
SUMl1ARY OF ANALYTICAL AND EXPERlMEID'AL RESUlJTS FOR A325 BOLrrS
IN A440 STEEL JOINTS
.'
.
CALIBRAl'ED IMPACT WRE1'1Cll
Tnrget Value
198 - 7/S" bolts
15
en
10
,'0
5
I
oL
35
30
I
J
40
45
CLAMPING FORCE, KIPS
Figure 2.
HISTOGRAM OF IKTERNAL BOLT TENSION
......:-:-.>--.i-.--~...... ~..____ _
___,-----'-.... _._-.. ,
---,,,-
-'j .i. ,)l);) '~~,
,{O~;;JX ,
...... _ ..... ....,.~ -
~
i
I...~--
Fig. 3
.
~
-
- ,
- --.-----.-'- --- -.
,
~
'Hydraulic Calibrator for
Torq~ed Inst~llat~on
,'_
I