Bolted Joints Slotted Holes
Transcript of Bolted Joints Slotted Holes
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BEH vIOR
OF
BOLTED JOINTS WITH
OVERSIZE OR SLOTTED HOLES
by
Ronald
N Allan
John W
Fisher
This work was carried out as part
of
the Large Bolted Connect ions
Project sponsored f inancial ly by the Pennsylvania Department of
Highways the Department of Transportat ion Bureau
of
Public Roads
and
the Research Counci l on Riveted
and
Bolted S tr uc tu ra l J o in ts
Technical guidance s provided by
the
Research Counci l on Riveted
and
Bolted S tr uc tu ra l J o in ts
r tz
Engineering Laboratory
Department of Civi l Engineering
Lehigh University
Bethlehem Pennsylvania
August 1967
r tz Engineer ing Laboratory
Report
No 318 3
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2
3
4
5
6
7
TABLE OF
CONTENTS
ABSTRACT
ACKNOWLEDGMENTS
INTRODUCTION
PREVIOUS
WORK
TESTING
PROGRAM
3 1 Description of Specimens
3 2 Plate Properties
3 3
Calibration of Bolts
3 4
Fabrication and Assembly of Joints
3 5 In strumen tation
of
Joints and
Bolts
3 6 Testing
Procedure
3 7 Loss in Tension Studies
TEST RESULTS N
ANALYSIS
4 1
Effect
of Hole
Size
on
Bolt Tension
and
Installat ion
4 2
Loss in
Tension
of
Bolts
with Time
4 3
Slip Behavior
4 4 Effect
of
Transverse Slotted Holes on the
Ultimate Str ength o f the
Joint
SUMM RY
TABLES AND FIGURES
REFERENCES
Page
i
3
6
6
9
9
2
4
6
9
9
3
24
8
30
3
58
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ABSTRACT
Twenty one
bolted
joints
were
tested
to
determine
the
ef fec t of oversized
or s lot ted holes on the
s l ip behavior and
u l t i -
mate strength
of
bolted
joints Hole
sizes studied
had
standard
1/4
in and
5/16 in . clearances. S lo ts
paralle l and
t ra ns ve rs e t o
the l ine of load
were
studied. All joints were fabricated from A
s tee l plate
and
fastened
by
in . A3 5
bol ts . Also studied
was
the
need for washers f or o ve rs iz e holes and changes in
bol t
tension.
For
holes
with 1/4 in .
clearance
there was no decrease in
the
s l ip
coeff ic ient excessive loss in bol t tension or inadequate preload.
The s tud ie s ind ic at ed that a washer i s desirable under th e turned
element to
p revent s ev er e gall ing.
A
decrease
in
the
sl ip
co-
eff ic ient
was observed for the joints with 5/16 in . hole
clearance
and for
those with
slotted holes.
Slotted
holes perpendicu la r to
the
l ine
of
load
did
not
decrease
the ultimate
strength
of
the
jo in ts
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CKNOWLEDGMENTS
The project has been sponsored f inancial ly by the
Penn-
sylvania Department of Highways the U.S. Department of ommerce -
Bureau
o f P ub lic
Roads
and the
Research
Council on Riveted and
Bolted St ruc tu r al J o in t s.
Technical
gUidance has been provided by
the
Council
th ro ug h an advisory committee under the chairmanship
of
Mr N G Hansen.
The authors
express their thanks
to
their
co workers
Geoffrey Kulak and James Lee for help
with
the tes t ing and to
Ken Harpel
and
his
laboratory
technicians. The manuscript was
typed by Daphne iversley
and
the photography and drawings done
under the supervision of Richard Sopko.
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1. INTRODU TION
The
current
1966
Speci f icat ions
for
S tr uc tu ra l J oi nt s
using STM A325
or
A49
Bolts ,
as approved by the Research Council
on
Riveted
and Bolted
S tr uc tu ra l J oi nt s
recognizes
two types of
shear connect ions , des igna ted as fr ic t ion-type
and
bearing-type,
respect1ve
y.
In a f r ic t ion- type jo int movement of t he connect ed
parts
is
not
tolerated
because of
the
detr imental
effects on th e b eh av io r
of the s t ructure .
For
th is type of jo in t s l ip const i tutes fai lure
and
working
loads must
be
resisted by fr ict ion
between
the connected
parts
with
a
reasonable
factor of safety against s l ip
Where sl ip of the bolted jo in t is not objectionable, a
bearing-type
connection
can
be
used. For
th is
type of
jo int
the
working
loads
may be
resisted by bearing of the bol ts against
the
sides
of th e
holes.
In
such
a connect io n, th e she ari ng of th e bol ts
or
fa i lure
of
the
connected parts i s c r i t i ca l
and
allowable stresses
are
based on the u lt ima te s tr eng th of
t he connect ion.
The present specifications
specify
tha t
the
bolts
in a
bolted
connection
are to be used in
holes
not more than 1/16
inch
in
excess
of the bol t
diameter.
l
There
are no provisions
in the speci-
f icat ions for the use of larger or
slot ted
holes.
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Most of
the
studies
on
bolted connections
have
used
t es t
joints having
hole s w ith
a
1/16
inch clearance. There
is
a
need to
evaluate the performance o f bolted connections
with
a greater amount
o f ove rs iz e
because frequently occurs because of
reaming
and
mis-matching. Slotted
holes
are
a lso o fte n necessary
when a new
s tee l
d 2 h d
structure
S connecte to an
eX1st1ng
structure. Bot overS1ze an
s lot ted
holes
are d es ira ble to permit
erect ion
adjustments.
The
purpose
of
this study is to
evaluate
th e
effect
oversize
and s lot ted holes have on
the
s l ip resistance and ultimate strength of
bolted joints . The results of
this
study should provide information
on whether
jo ints with ove rs iz e
or
slotted hol es f unct ion
sat isfac
to r i ly as friction-type or bearing-type
connections.
The
study
is
primarily concerned
with the effect
oversize
and s lot ted holes have on: 1 losses
in
bol t
tension
a ft er i ns ta l
lat ion,
2
th e
s l ip resistance of a jo in t 3
the abil i ty
to tig hte n
bolts using the
standard
ins ta l la t ion technique, 4 whether washers
are
needed
for oversize
holes
and 5 the changes in
bol t
tension
during tes t ing.
The effect
of
slotted
holes
placed
perpendicular
to
the
l ine of loading on ultimate strength was also observed.
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2
PR V OUS
WORK
Various studies have
analyzed t he behav io r
of
high strength
bolts and
bolted
joints when the bolts
were
ins ta l led in holes larger
than
their diam eters. E arly
laboratory
and
f ield t es t s indicated
tha t
among
other things,
high strength
bol ts
could be ins ta l led in
holes up
to
1/16 in . larger than the i r d iameter wi thou t a noticeable
effect on the
performance of the bol ts or of the jOints.
3
Therefore,
the
Research
Council
on
Riveted and Bolted
Structural
Joints
per-
mitted a
bol t hole clearance
of
1/16 in .
in the i r
f i r s t
specifica-
t ion
issued in 1951.
4
Hoyer
reported in 959 that studies conducted in Germany
indicated
that
there
was no
influence on
the sl iding
load
for holes
up
to
1/8-in.
larger than
the bolt
5
Chesson
and Munse
studied the
effec ts
of t ightening
bolts
in holes
with
up to 1/8 in . clearance using
the
turn-of-nut method
with and without
washers
under
the
turned
element. They concluded
that
oversize
holes up
to
1/8 in .
greater
in diameter than the bolt
may
cause
some reduction in bol t tension when washers are omitted and
when
f inished
hex head bol ts and nuts
are
used,
but
the clamping force
wil l
s t i l l be
in excess
of the required tension for
A325 bolts See
Fig.
1
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4
Studies
to determine th e loss in prelo ad o f high strength
bol ts
due
t o r el ax at io n
have
generally indicated
that
the
to t l
loss
is
about
1 of
the
in i t i l preload.
Research
conducted in Germany
since
1954 has
shown
that high strength bol ts lose about 1
of
h
1
d d 6 7 Al h
1
d
e1r pre
oa
over a
two ye ar per10
so t e pre oa was un
8 9
affected
by
temperature
changes.
In South
Africa Denkhaus ob
served that the
loss
in
bol t
load using
a
washer
was
about f ter
1
day and 2 from
1
day to
1
year. Studies on
high tensi le bol ts
in
Japan
lO
showed
bol t relaxations of about
6
f ter 11
years for
bolts
tightened
to their y ie ld p oi nt .
Chesson
and
Munse
5
also
observed
the
effects of h oles w ith
up to
1/8
in .
clearance
on
the relaxation of A325
bolts. They
found
that there was no
signi f icant difference
in the amount of bol t ten
sion
los t
with
time
for
the
1/8 in . clearance
holes ei ther with or
without washers .
The loss in
bol t tension for l l tes ts
was
less
than 1
over
a period
of
from
1 to
5
days.
Tests conducted by the
Lamson
and Sessions
Company on a
load
analyzer showed a loss
in tension of less
than
1 over
a period
11
of days.
A
study to determine
the decrease of
the
preload in
high
strength bolts over a period of time was
conducted
in the Netherlands.
12
t
was
concluded that the
loss would be
about
5 over 2 years for
a
bol t with 2
washers
and about
1
over 2
years for a bolt with one
washer.
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5
Studies to determine the changes in tension
in
the bol ts
f
1 d
1
d d d
Leh·
h
U
13a
o ~ n t
as
oa
was app
were
con
ucte
a t
n ~ v e r s ~ t y
Bolt tension
decreased
from
1 to
8
a t
major
s l ip
due to
the
Poisson
effect
Joints
with a 4 in . grip showed a decrease
in bo lt
tension
after major s l ip Nester
14
observed a decrease in bol t tension from
o to 8.6
a t
major s l ip
There is
no
record of
any research
done to
date
on the
effect
of
s lot ted
holes
on
the
performance
of
ei ther
high strength
bol ts o r bo lted jo ints
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3.
TESTING
PROGRAM
3.1 Description of Specimens
All
twenty-one
t es t specimens
were
fabricated from l n
A36 s tee l plate supplied from the same heat. They had two l ines
of
1 in .
diameter
A325 bol ts connecting
four
plies of
plate
at a
pitch
of 5-1/4
in .
The faying surfaces were clean
mill s ca le .
Twelve
specimens wit h hole s
of varying
amounts of
oversize
and
three
specimens
with slotted holes
were
des igned a s fr ic t ion-
type jo in ts . The geome tri ca l la yout o f
the
oversize hole jo ints is
shown in Fig. 2.
The
twelve
joints with oversize holes were divided
according
to
hole
size
into
four
groups
of three
jo in ts .
The
ra t io
of
net
plate
area to to ta l bolt shear area the A A ra t io was 0.68.
n s
The
f i r s t group of three jo in ts
designated
OH
had a hole
diameter
of
1-1/16
in . providing the maximum allowable
hole
clearance
of 1/16 in .
These
three jo ints served as control specimens.
Because
the holes
were
normal
s ize
the bol ts
were
instal led
without
washers.
I n ano th er phase of this research
project
a number
of
bolted jo ints
were
tested to
determine the
influence
o f v ar ia tio n
of
the contact area upon the s l ip
resis tance.
These spec imens were
fab-
ricated from the same
plate as
the specimens
being
discussed. The
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faying
surface
condition was ident ica l
for
both
groups of
jo in ts
The joints
of
the l a t t e r series had a single l ine of
four
7/8
in .
A325 bol ts and
the
contact
area
was
varied
by insert ing washers be
tween the
main and
lap pla tes . The hole
diameter
was
1/16
in . larger
than
the bol t
size.
The
three control specimens for
the
series
did
not have washers between
the plates. Thus the
phys ic al cond it ions
affecting the sl ip behavior were the same for these
control
specimens
as
they were for
the
th re e con tr ol jo in ts ORl
series
of the oversize
hole j oi nt s eri es
Therefore
a
direc t
comparison of the sl ip
co
eff ic ients
can
be
made.
The second
group
of
three
jo in ts designated OR2
had
a hole
diameter
of
1-1/4
in .
providing four times the
maximum
a ll owab le hol e
clearance. These jo in ts were also
bolted
up without washers.
The third
group
designated
OR3
also
had
a
hole d iame te r
of
1-1/4
in .
These were bolted up
with
washe rs under the nuts
in
order
to
determine whether
or
not washers should
be
required for holes of
th is
amount of
oversize.
The
fourth
group of jo in ts designated OR4 original ly
had
hole d iameter s
of 1-3/16 in . which provided three times the maximum
a llowable hole
clearance.
The
holes
in
these
three
jo in ts
were
en
larged to 1-5/16
in .
when the joints with
the 1-1/4
in . holes indi
cated no
signif icant
change
in s l ip behavior from th e c on tr ol specimens.
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8
The nine jo ints with slot ted holes had
th e
slots placed
in the middle or main plates . Slotted h ole s lo ca te d in outside
pl ies would
normally
be
covered
with large
washers
which
would
cause
these pl ies
to act a s e nc lo se d plates similar
to th e t es t
jo in ts .
The s lots were
2 9/16 in . long and 1 1/16
in .
wide.
The
holes in the outside plates provided
the
maximum allowable hole
clearance of
1 1/16 in . The jo ints were assembled
without
washers.
Three jo ints SR1
contained s lo ts
placed
para l le l
to the
l ine
of load as
indicated
in Fig. 3.
These w ere
designed as f r ic
t ion type jo ints
and the
A /A ra t io was the same
as that
of the
n s
oversize
hole joints
so
that
th e
effect of slot ted holes placed in
the
direct ion
of s l ip on
the sl ip resistance could be observed.
Six
jo ints
were
designed
as
bearing type jo ints
and
had
s lots placed perpendicular to the
l ine
of load as shown in Fig. 4.
Three of
these jo in ts
designated
SR2, were
proportioned
with current
l y u sed a llowable st resses and fai lure
was expected to
occur
by tear
ing
of the
plate a t
the net section. Their net
section
area was
equal
to
the bolt shear
area. The
net section
efficiency was 60
The
remaining
three
jo in ts
designated SR3, had an
in
creased
net
section area so that fai lure
would
occur
by shearing
of
the
bolts . Earlie r experimental and
theoret ical
studies
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ha d shown that
this
would occur i f net sect ion area was 6 greater
than
bol t
shear
area.
3.2
Pl at e P rope rt ie s
The A 6 s tee l plate used
for the
specimens was purposely
ordered
a t
minimum
s t rength.
The plates
furnished
from the same
heat were
rol led
2 8 1 /2 i nc he s wide and 4 feet long. A f o o ~ -
long
section
was
cut
from
the
middle
of
each
plate
Standard
ten-
s i le
coupons cut from
this
piece were
tested in a mechanical uni-
versal tes t ing
machine
equipped with an
automatic
load s t ra in
re -
corder . The tes t ing speed was
0.025
inches per minute unt i l
s t ra in
hardening began. The
s ta t ic
yield load was obtained by stopping
the machine times during yield and allowing
the
machine
to
equalize
each
time.
When the coupon
went
into
s t ra in
hardening
the
tes t ing
speed was
i nc re as ed to
0.3 inches
per
minute unt i l the coupon fai led
The load s t ra in curve for an 8 inch gage
length
was plot ted by
the
automatic rec ord er fo r
each
coupon.
Fifteen s ta nd ar d b ar tensi le
coupons were tes ted.
The
mean s ta t ic
yield s t ress
of
the
plates was
29.3
ksi with a standard
deviation
of 0.6
ks i
The mean
tensi le
strength was 61.0
ksi
and
i t s standard
devia t ion
was.D.7
ks i
3.3
Calibration
of
Bolts
One i nch d iame te r A 5
bol ts
were
used
to bolt up
a l l
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jo in ts
Because some
joints were bolted
up with
washers and
some
without;
two different
bol t
lengths
were
required. Joints
without washers used 5 1/4 in . b olts; joints with washers used
5 3/4 in
bol ts
Representative samples of bol ts from each lo t were ca l i -
brated in both direct tension and
torque
tension
to
determine
their propert ies. Three bolts from each lo t were chosen
at random
for
each
cal ibrat ion.
All
of
the
calibrated bol ts
sat isf ied
the
minimum
proof load and ult imate load requirements specified by the
ASTM Both
lots
of bolts had tensi le strengths that exceeded mini-
mum strength
by
13 to 15 In
both the
direct tension and torqued
tension cal ibrat ions
the
bol ts remained e las t ic well above
th e
required minimum tension. Since
the bol ts
were held a t
the
same
grip
when
tested as
existed in the joints
t he load e longa tion
curves used in
the
torqued tension cal ibra t ion tes ts were .used
to
determine the
tension in
the bolts instal led in
the
joints
3.4 Fabrication
and
Assembly
of Joints
The
t es t
jo ints
were fabricated
by a
local s tee l fabri -
cator.
The
individual plates were
flame cut
to rough size and
t hen m il led to the
specified
jo int dimensions. The
faying
surfaces
were
cleaned of
loose mill
scale and burrs .
The
four c orn er h ol es
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of each
oversize hole
joint assembly were then sub dri l led
and
reamed f or a li gn ment . he fou r r emaining holes were
then
dr i l led
through a l l four
plies of
s tee l
to the
s pe ci fi ed s iz e
while the
plates
were
held in alignment
by
s tee l pins in
the
corner holes.
he s lot ted holes were f o ~ m by dr i l l ing two adjacent
holes in the plate and then
removing the
metal between
them.
Fil le r plates were welded to the lap plates on
one
end
of
each
jo int nd the m in
plates
were welded together at the
grip
end to ensure
uniformity of
wedge
g rip a ctio n during
t es t -
ing.
Cleaning assembly
and i ns trumen tat ion of the
joints
were performed at Fritz Engineering Laboratory. Before assembly
the
jo ints were
cleaned
with shop solvent to remove any
grease
or other
foreign
material . hey were then assembled and aligned.
he bolts were
instal led
either w ith or w ith out washers
depend-
ing on the individual t e s t · he turn of nut ins ta l la t ion
pro-
cedure
w s
used.
he
bol t
tensions were
determined
by
measuring
the changes in bol t
length
with the extensometer and
then
de-
t er mining the cor re sp on ding
bol t tension from
t he to rq ue d
tension
cal ibra t ion
curve.
In a l l
of
th e
jo ints except the
three
with
hole dia-
meters of 1 5/16 in the bol t tension
varied from
the
required
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minimum tension
to
50
above t he r e9ui red
minimum tension. When
two
of
the
joints
with
the
1-5/16
in .
holes OH4
ser ies
were
bolted up with washers
under
the nuts only half of the bol ts
failed
to
achieve
proof
load f ter 2 turn
of nut. The
bol ts
were removed and l l
three
jo ints were
bolted
with washers placed
under
both the
heads
and the nuts.
3.5 Instrumentation of Joints and Bolts
All
of
the specimens were instrumented
to record the i r
performance
during
tes t ing
including
jo in t
s l ip elongation and
alignment.
Dials
reading
to
0.0001 in .
were attached to tabs
tack
welded
to
both
sides of
the
main plate
in
l ine with
the bottom
row.of
bolts .
The
pointers
of these
gages
rested
on
a
frame
tack
welded to the lap plates in l ine with the tabs. Thus s l ip move-
ment
between the
main and lap
plates
was measured on one
l ine
and
effects
due
to axial
strains were
minimized.
Joint elongation was measured between points one
gage length above the to p l ine of bolts and
points
one gage
length
below
the
bottom
l ine
of
bol ts .
These.
points
were
locat
ed
on the
center l ine of
the
joints
the
top points on both fa ce s
of the main plate and the
bottom
points on both lap plates . ne
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13
half inch studs were tack welded to
th e plates
a t these points .
Elongations
were
read
from
0.0001
in .
dials
that
read the
re-
lat ive movement
of
the studs by means
of
a
sl iding
rod arrange
ment.
Elect r ica l resistance s t ra in gages were attached to the
sides of the main and la p
plates of a l l of
the joints
to
detect
any eccentr ici ty of loading caused by uneven gripping or curva-
ture
of the
joint
and
also to
determine
the onset of
yielding.
number
of the
bolts
were
ins trumented with
elect r ical
resistance fo il s tra in
gages
cemented to their shanks. Flat
areas 1 1/16
in .
long
and 1/16 in . d eep were milled into
th e
shank
under
the bolt
head
to
provide
a
mounting surface for the gages.
he
gages
were placed on opposite sides
of
the
shank
paral le l
to
the axis of the
bol t . he
g ag e w ire s p ass ed thr ou gh
two
holes
dr i l led
through
the bol t head.
t
was d isc ov ered during th e direc t tension cal ibrat ions
that the
shanks
for
the
bolts
remained
elas t ic into the range of
bol t tension achieved by the turn of nut method of
ins ta l la t ion
and
a l inear
load strain
relationship existed
as
shown in
Fig.
5.
Since the gaged port ion remained e las t i c i t
would
no t
be so affected by the high load and very l i t t l e creep would occur.
the other hand ine las t ic
deformation was
occurring
in
the
threads
so
that the overal l bol t elongation could not be expected
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to yield
consistent
results
Each gaged
bolt
was
calibrated
in d ire ct
tension
in
order to re la te the
strain r eadings with
the
tension
in the bol t .
During
the cal ibrat ion,
the
bolts were
loaded
in
10
kip
incre
ments
to
50 kips and
then
in 5
kip
increments
to
65
kips.
The
ove ra ll b ol t elongations were also
checked
with the extensometer .
I t
was observed that
the
reduced
area
of shank
due
to
the m illed
surfaces did
not cause
any
measurable
difference
in
th e
l o ~
elongation relationship
of
the bolts
as
compared
to the
bolts
without gages. The load-strain
reading
relationship of the
gaged
bolts was l inear for
both
the loading
and
unloading cycles.
Four gaged bol ts were used in each of
six
of the
bolted
joints: OH1 1 and OHl 2 1-1/16
in . diam.);
OH2 l 1-1/4 in . dia
no
washers);
OH4 l
1-5/16
in .
diam.,
2
washers);
SHl-1
slots
paralle l to
l ine
of
load);
and SH3-l
slots
perpendicular
to
the
l ine of load). The bolts were arranged in a staggered pattern
as shown in Fig.
6.
3.6 Testing
Procedure
All of the
joints
were
tested
in
a
5,000 kip
universal
test ing machine us ing f la t wedge grips. Each jo in t was
held
by
the
top
grips
of
the
machine
while
dials were ~ l e d on
th e sp eci
men The
dials
and s tra in gages were a l l read at z ero load. The
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15
bottom grips
were
then applied
and loading
s tar ted .
Load was
applied
in
25
kip
increments
un t i l
major
s l ip
occurred.
At
each
increment a l l
dials
and
strain
gages were read.
For the friction type jo in ts
the
s l ip behavior
was
ob -
served closely. Following major s l ip the dials
and
gages were
read
and load
was applied
in
kip
increments unt i l another s l ip
smaller
than the original
s l ip and designated
as
a minor s l ip
occurred.
This
loading
sequence
was
repeated
for
a l l
subsequent
minor
sl ips unt i l the
jo int
went
into
bearing at which
time
the
t es t was
stopped.
For th e b ea rin g joints the t es t was
carr ied
to ul t i -
mate and fa i lure .
The
i n i t i a l s l ip load
was
observed and the
jo int
was
then
loaded
in
5
kip
increments
unt i l
th e
load
approached
the predicted ul timate
strength.
The
p la te f ai lu re
specimens were then
loaded
to
fai lure
whjch occurred when th e
main
plate tore
apart a t the
top
l ine of s lots The b olt f ailu re
specimens were loaded unt i l the top
row
of b olts f aile d in shear.
After the joints were
removed
from the tes t ing machine
each
one
was
dismantled.
The
fracture surfaces of the
plate
failure
specimens and
faying
surfaces
were
inspected.
A sawed
sect ion
of one of
the b olt f ailu re specimens
was
taken to in -
spect the
condition
of the bolts and the
s lot ted holes.
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3.7
Loss in Tension
Studies
Immediately
fter the nu t on
high strength
bol t
is
t ightened loss in
bol t
tension
occurs. This
is
thought
to be
resul t of creep
or plast ic
yield in t he th re ad ed port ions and
e l s t ic
recovery caused by pl s t ic flow in the s tee l plates
under
the
head
nd nut. om research
has been
done on holes with the
s ta nd ar d h nl e c le ar an ce o f 1/16
in .
Only few relaxation
t es t s
have been conducted on larger holes.
t
w s
desirable to e va lu ate
the
effect
on relaxation
of holes tha t
were
substant ia l ly
oversize.
he largest hole
size studied w s 5 16
in .
oversize
2 1 2 times the mount in
previous studies
of holes 1 8 in .
oversize.
he effect of the
enclosed slot ted holes on loss of bolt
tension
w s
also
eval-
uated.
Since t he load e longa tion relationship of the bolt
shanks
w s l inear within the range of bol t tension used the
bol ts with the str in gages
cemented to thei r s hank s s ho ul d give
an accurate
indication of the bolt tension a t any time. hus
meaningful
relationship of the bol t
tension
varia t ion with
time
could be established. he six bolted joints containing the gaged
bol ts
provided good representat ive sample of l l
of the
joints
in
the study.
he
six joints were
placed
horizontally and were
not
disturbed
for the
duration
of the study. Strain
gage
readings
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were taken
a t the
moment each bol t was
ins ta l led
Subsequent
readings
were
taken
a t
one
minute
five
minutes
one
hour
one
week two weeks and one month after
ins ta l la t ion
The
strain
gage indicator
remained
connected
to the
s tra in
gaged
bol ts
through a
switch box for the duration of the
study. In addi-
t ion
to
the strain gage
readings
extensometer
readings
were
taken
a t the
same
intervals on a l l
bol ts of each jo in t This
provided
an opportunity to correlate the s tra in readings on the
bol t
shanks
with the bol t elongation
readings.
t
the
completion
of the stu dy the six joints were
tested
using
the
standard
procedure.
During
each t e s t s tra in
readings were
taken
so
tha t the
changes
in bolt
tension during
tes t ing
could
be
observed.
In order
to
check
the
accuracy
of
the
bol t
gage
readings
over an
extended
period of
time
gaged bol ts
of the
same lo t were
instal led in
a
load ce l l as
shown
in
Fig.
7.
The
load ce l l
was
made
of hardened tool
s tee l and had a hole
1 1/16 in . in diameter
through i t s
center
through which
the
bol t
was
inser ted .
Four
strain
gages
were
cemented to the outside of the load ce l l two
placed horizontally and
two
placed ver t ica l ly
They
were con-
nected to
a
strain gage indicator in
a Wheatstone bridge arrange
ment.
One half
inch thick A
s tee l plates were
placed
over
each en d of the load
ce l l
so that the behavior of the plates
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under the head and nut
would
be
similar
to the behavior
of
the
plates in the actual jo in ts
Three
sets
of these
plates were
used one
se t
for each of the three
hole
diameters used
in the
oversize
hole specimens.
The
tot l grip of
the
assembly
was
inches.
Thus the
condit ions
tha t
affected the
relaxation be-
havior of
a bolt in the
t es t
joints were closely approximated.
The bolt to be studied was ins tal led while the load ce l l
assembly
was
firmly held
in
a
vise.
The
bolt
gages
and
the
load
ce l l
gages
were connected to sep arate str in
gage
indicators
set to indicate a load of 6 kips. The
nut
was t ightened by a
hand wrench
unt i l the
desired
load was reached. Readings were
taken for both the bol t
tension
and load ce l l
deformation
t
intervals
of one minute
5
minutes
one hour and
each
day
for
a week.
Overall
bol t elongation
readings
were also taken
with
the extensometer.
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4.
TEST RESULTS
AND
ANALYSIS
4.1
Effect of Hole Size on Bolt Tension and Ins ta l la t ion
I t is of in te res t to examine the effect of
varying
hole
diameters
on the ease of ins ta l la t ion degree of scouring,
and clamping force of bol ts
ins ta l led
by th e
turn-of-nut
pro
cedure.
The bol ts
in the
OHl joints 1-1/16 in . hole diameter
were ins ta l led without washers in accordan ie w ith th e present
specifications for
bolted jo in ts which permit ins ta l la t ion
without
washers
when using the
turn-of-nut method. There
was
no diff icul ty
in
achieving a
bol t
tension
above the required
preload in these
jo ints
The tension achieved in
the
4
bolts
of the control jo ints ranged
between
5
and
49
of
the
requi red pre load ,
as shown
in
Fig.
8.
The average
bol t
elongations
and
tensions
for
each jo in t are
l is ted in
Table 1.
The mill
scale on
the
plate area under
the
turned
element
around
the 1-1/16 in . holes was
s l igh t ly
galled as shown in
Fig.
a
A s l igh t
depression occurred
under
the
bol t
head,
as shown in Fig. 9b. This
nominal
amount of damage indicates
tha t
washers
are not
required
under
the
head or
the
turned
element for
holes tha t
contain
the
nominal
amount of
clearance.
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The bol ts
in
the 3
joints
of the
OR
series i l /4
in .
hole diameter were insta l led without washers while the bolts
for
the OR series also
1-1/4
in . hol e d iame te r were
installed
with
washers under the turned e lemen ts .
There
was no diff iculty achiev
ing bol t
tensions
above the minimum required tension in a l l six
jo in ts . The
average bolt
elongations and tensions
for
th e two
series are summarized in Table 1.
The
range
of
bol t tensions
achieved for each series is shown in Fig. 8.
As can be
seen in Fig.
8, the
average
bol t
tensions
for
the
two groups containing 1-1/4
in .
holes were about equal 118
of proof load
but
were noticeably lower than th e average tension
in
the control groups 130 of proof
load .
Plate depressions
occurring
under
bolt heads during t ightening
Fig. lOa
were
greater
than
those that had occurred in the control joints .
This
meant
that t he e longa tions
of
th e
bolts in
th e
1-1/4
in . holes
were sm aller than those in
the control
joints af te r 1/2 turn-of
nut and
hence the
bol t
tensions were
reduced.
Severe
galling
of both the
plate
and th e nu t had
oc
curred
during
ins ta l la t ion in
the
OR ser ies .
The damage to
the
plate
is shown in Fig. lOb. For comparison, th e s ur fa ce
con ditio n of the plate where washers were used under th e nuts
in
the
OR
series is shown in
Fig. 11. Only
a s,light
depression
occurred under the
washer. I t can
be
seen from Fig.
8 that th e
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of washers in the 1 1/4
in .
holes did
not
affect the average clamp-
ing force
of
the bol ts . However the scat ter in bolt
tens.ion
for
the
bol ts
without
washers
was nearly twice
as
large as the
scat ter
in the bolt te ns io n fo r the
bol ts
that were instal led
with washers.
The 1 3/16 in . holes in the OH4 s eri es jo in ts
were
dr i l led
from the original to
1 5/16 in .
af te r the
studies
on the s l ip
be-
havior
of the
OH2
and
OH3
series. The
bol ts
in two of
the three
OH4
s erie s jo in ts were
ins ta l led with
washers placed
under the
nuts
be-
cause
of
the
severe gall ing
that occurred
in the OH2
series
when the
bolts were ins ta l led
without
washers. When the bolts in these two
specimens were t ightened by t he s ta nd ar d turn of nut procedure
hal f
of
the
6
bol ts failed
to
achieve the i r
required minimum ten-
sion. The
bolts
were removed from the
jo in ts
In spection of the
two jo ints revealed
tha t
the
bol t
heads
had
recessed
severely into
the
plate
around the
holes
far more than
in the OH2 and OH3
ser ies
as
shown
in Fig. 12 . In this instance the
elongations of the
bolts
were
reduced suff ic ient ly
so
that
the
bol t preload
was
less than
the required
minimum
All three OH4 joints were then rebolted with washers
in -
stal led under both
the
heads
and
nuts. This time there was no
diff icul ty in achieving bol t
tensions
above proof
load
as
indica ted
in Fig.
8.
The range of
tensions
a ch ie ve d f or bolts
ins ta l led
with
washers under
both
the.head and the nut was from 11
to
144 of
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proof load with
an
average
tension
of
125 of
minimum
tension.
This
compares
with
the range
of
bol t
tensions
achieved
in
the
bol ts in
the control
joints
The resul ts
of these studies can be extended to
determine
the
maximum a llowable hole c le ar an ce f or
other
sizes of A 5 bol ts
for the
given grip
length in A36 steel plate . The diff icul ty in
achieving
proof load tension
was a resul t
of the
bol t
depressing
in -
to
the
pla te
around
the
hole. In
the holes with
the
5/16
in .
clear-
ance
the
bol t
heads r ecessed severe ly
into
the
plate because
the
bear ing pressure
between
the f la ts
of the
heads and th e plate was
in i t ia l ly
to o high. This was no t
the
case for th e bol ts that were
in sta lle d i n
the
holes with 1/4 in .
clearance. t can be assumed
tha t
the bear ing pressure developed under the f la t areas of the
bol t
heads
with 1/4 in . clearance
holes
was the maximum a llowable bea ring
pressure.
t was 72 ksi when
the
bol t preload was 2 in excess
of
the
required tension.
The maximum
hole clearance
for
any size
bol t
may then
be computed
on
the basis
tha t
the area of
plate
re-
maining under
the f la t of the head must be suff ic ient to
permit a
maximum
bearing
pressure
of
7 ksi when the
bol t is
ins tal led
The resul t s
of these
computations
are
summarized in Table
2 All of
the
hole d iameter s have
been rounded
off
to
the
nearest
sixteenth of
an
inch. The maximum a llowable hole
clearance
for
bol ts
equal
to
or
less than one inch in diameter is 3/16 in . Fo r
bol ts with d iameter s greater than
one
inch a 5/16 in .
hole clearance
is
permissible.
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4 2
Loss
in Tension o f
Bolts
with Time
The
loss
in ten sio n
on e
minute a ft er i n st a ll a ti o n
agreed
w ith the
one-minute l os se s r ep o rt ed in
previous
inves t iga t ion S
where the
loss
in t ens ion fo r heavy-headed bo l t s and nuts ranged
be
tween
and
4
of the i n i t i a l
clamping
fo rce
Nearly a l l
of
the loss occurred within the f i r s t few hours
a ft er i ns ta ll at io n Also none of the var i a t ions
of
hole diameter
o r the
presence of s lo t s
had any s ig n if ic a nt e f fe c t
on
the p e rcen t
loss in ten sio n of
the
bo l t s dur ing the
study period of
one month.
The extensometer readings
indica ted t h a t the ungaged b o l t s behaved
the
same
as
th e gaged
bo l t s
The load c e l l
s tu die s are
compared
with
the bo l t
gage
readings
in
Table
4.
Since v i r tua l ly a l l of the losses in th e bo l t s
ins t a l l ed
in
the j o in t s occurred within week a f t e r i n s t a l l a t i on
the load c e l l
s tud ie s were
a lso conducted fo r
one
week.. The
re su l t s
showed good agr eemen t b etween the b o l t s t r a in measurements and th e
load
c e l l The maximum er ro r was
2-1/2
of
the i n i t i a l clamping
force
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4.3
Slip Behavior
The
s l ip
resistance
of
a
bolted
joint
is
a function of i t s
s l ip
coeff ic ient and the bol t preload. The
s l ip
coeff ic ient ha s been
defined
as:
15
K = PINT. where K
is
the
sl ip coeff ic ient
P
the
s s s s
s l ip load N the number
of
s l ip
planes
and T
the
to ta l i n i t i a l clamp
ing force.
The
to ta l
clamping
force
was
taken
as
the
sum
of
a ll
of the
bol t tensions measured approximately one minute after
ins ta l la t ion
The s l ip coefficients for
each of the
joints are
summarized
in
Table
1.
Typical load-slip and load- joint
elongation
re la t ionships
are
shown
in
Figs. 14 and 15 .
The
load-slip response
of
the oversize and slot ted
hole
jo ints
was
l inear
unt i l
the
load approached
the re gion
of
major
s l ip
The
dia l
gages that recorded s l ip moved
very s low ly in
this region.
Occasionally there
would
be a sl ight
noise and
the
sl ip dials would
indicate a
sudden
movement of about 0.0001
in . This
was
probably
caused by the extension of the sl ip
zone
into the joint h n the
load
approached the major
sl ip
load
the dia l
movement began
to
ac-
celerate and when
major
s l ip
occurred
there was a
loud
noise accom
panied
by a
sudden
movement about 0.04 in of
both
the sl ip and
elongation
dials which caused
a
drop
in the
tes t ing
machine
load.
The in i t i a l
sl ip
was never equal to the hole clearance of the joint
Subsequent loading of the
bolted
joint produced small additional
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s l i p s un t i l the
j o i n t
was in bear ing These smal l s l i p s
seldom
oc
curred
a t
higher
loads than
the
major
s l ip
load
The
number
of
smal le r s l i p s increased as the hole diameter increased The
i n i
t i a l s l ip did
not br ing
the j o in t
in to bear ing because of
the
de
crease in lo ad c au se d by
the
s l i p In an a ctu al s tr uc tu re th e load
might
remain
cons tan t and the j o i n t would s l ip i n to bear ing a t th e
i n i t i a l s l i p
The
three
j o in t s
of the OHl
se r i es
which
had
the
nominal
hole c learance
of
1/16
in
served as
con t ro l
specimens The average
s l ip coe f f i c i en t fo r these three j o in t s was 0 29 T his v alu e i s com
14
parable
to
the average s l ip
coe f f i c i en t
of 0 34 obtained by Nester
from a
se r ies of bol ted connect ions made
from
th e same hea t o f s t ee l
16
Tes t s conducted a t
the
Univers i ty o f s h ~ n g t o n on
A 6
s t e e l bol ted
j o in t s yie lded
comparable
r e su l t s
Inves t igat ion of the faying
sur faces
of
the j o i n t s ind ica ted
tha t
damage to the
m il l sca le
sur face
was
confined mostly
to
the
a r ea s
immediately ad jacen t to
the
hole s This i s in
accordance with
the
theory tha t
the
areas immediately adjacent to
the ho les
of
a
bol ted
j o i n t
a re the a reas of
h ig he st c on ta ct
pressure and
t he r e fo r e
provide
most
of the s l ip r es i s t ance Figure
16
shows
the m ill sca le surface
damage near the bo l t
holes
The OH
and
OR j o in t s with the 1 /4 in hole c learance
pro
vided s l ip
r es i s tance comparable
to the
OHl t e s t s
The average
s l ip
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coeff ic ient for both
the
OH
and
OH
series
was 0.28. Inspection
of the
faying
surfaces indicated that
most
of
th e s urfa ce
damage
occurred around the holes See Fig. 16 . This also
showed
that the
pressure distr ibut ion in these
joints
was
similar
to the pressure
distr ibut ion in the control joints
damage was more
severe for
the
1/4 in .
hole clearance joints
because
the distance
of sl ip
was
four times as great.
The
three
joints
of the
OH4
series
which
had
hole
clear
ances of
5/16
in . showed lower sl ip resis tance. The average sl ip
coeff ic ient for
these joints was 0.24. Inspection
of the faying
surfaces
af te r tes t ing also
showed
that most of the
surface damage
occurred
around the holes. The damage for
these
jo ints was
the
most
severe
of th e oversize-hole joints
because
the greatest amount of
s l ip occurred.
The three fr ic t ion joints of the SHl group had slot ted holes
in the
enclosed
plates
placed paral le l to the l ine of load.
These
joints also
showed
lower s l ip coeff ic ient .
The
average sl ip coeff ic ient
for the series
was 0.20.
The
sl ip behavior of
three of the
bearing
joints SH2-i,
SH
and
SH3-l
was different
from
that
of
the
res t
The
behavior
of
these three
joints
prior
to major
sl ip
was
basical ly
the same
as
the
other joints
slow
dia l
movements with an bccasional sudden move-
ment of 0.0001 inch.
When
major s l ip
occurred
there was no loud
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-27-
noise or drop
of
load. Instead,
the
dials began
to
move
very rapidly
while
the
load continued to increase.
The
to ta l amount of rapid
dial
movement was enough
0.30-0.50
in
to
be considered a
major
s l ip
Following
this the joints
underwent
a few minor s l ips unt i l the bolts
went into bearing. The s l ip coeff icients of the
six b earin g jo in ts of
groups SH
and SH
are also
summarized
in Table 1.
The average s l ip
coefficients for
the
SH
and
SH
series
were 0.23
and
0.21,
respec
t ively.
The
average s l ip coeff ic ients of a l l
of the
j oi nt se ri es
are
compared
in Fig. 17 . I t is apparent that
th e
average sl ip co
ef f ic ien t
for the
OH
and OH series was
about
the same as
the aver
age
s l ip
coeff ic ient of the OHI
jo in ts
There was a decrease in the
s l ip coefficient
for the OH4
jo in ts
This indicates that
for
in
bolts
there
is
no decrease in
the
sl ip
coeff ic ient for holes with
up
to 1/4 in . clearance.
The
s l ip
coeff icient
for a l l
of
the s lotted
holes
were also lower than the average s l ip
coeff icient
of the control
joints
A
possible
hypothesis
to
ex pla in th e reduced
sl ip resistance
of
th e
OH4 joints 5/16 in . clearance and the s lotted
hole
jo in ts is
based on the theory that the greates t
con ta ct p r es su r e
between two
plates bo lt ed togethe r
occurs
immediately adjacent
to
the hole.
High
f r ic t iona l forces that are p ropo rt iona l t o the contact
pressure
the
interlocking
of the
stir
face i r regular i t ies in
these r ~
con
s t i tu te a
major port ion of the resistance
of
the bolted jo in t
to
s l ip
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28
Removal
of
a large port ion of this area as
in
the case
of
the OH4
jo ints
with
5/16
in .
hole
clearance
and
the
slot ted
holes
causes
very high
contact p ressu res
immediately adjacent
to
th e
hole
which
tends to
f l t ten
the surface i r regul r i t ies This r ed uces the
sl ip
resistance of the joint This reduced
resistance
to sl ip should
be
taken into
considerat ion
in
the
design of fr ic t ion type joints
con
ta ining
l ar ge o ve rs iz e
or slot ted
holes.
4.4 Effect of
Transverse
Slotted
Holes on
the
Ultimate
Strength
of
the
Joint
The three
joints
of the SH2 series
were
designed to
f i l
by tearing of the plates .
The
resul t s of these t es t s are summarized
in
Table Sa. The
load joint
elongation and load specimen
elongation
re la t ionship
of
jo in t
SH2 3 is summarized in Fig. 18 .
In l l cases th e inter ior s lo tt ed p la te
failed
a t the
f i r s t
row of slots Fig. 9 shows t he d eforma tion
in
the slot ted
holes of jo in t
SH2 2
at f i lure
The ultimate
load for l l three
specimens was
r o u ~ y
11 of
the
predicted
load
based on the coupon tes ts
This
is
in
agreement
with the resul ts of
e r l ier studies conducted on bolted
5
jo ints
w ith s tand ar d round holes.
The three
joints
of the SH3 series ¥ere
proportioned
so
that
fai lure
would
occur by s he ari ng o f the bol ts . The geometry of the
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29
joints was
based
on the assumption that minimum strength bol ts were
to
be used
for the t es t s However
the shear strength of the
bol ts
exceeded the plate capacity and joint SH3 l failed
by a
tear ing of
the
plate.
A new lo t of bolts
specified
to be
of
minimum strength
was ordered. The bolts were tested
in
shear
j igs
with
both s lotted
and round
holes.
The average shear strength of the bolts in the
slot ted
hole
shear
j igs
was
84.3
ksi
while the shear
strength in
the
round hole
was 81.3 ksi . This was
caused
by a
ballooning
of th e
plate as the bol t shearing caused deformation on the f la t
port ion
of the s lot as shown in Fig.
20.
T hi s cau sed a shif t ing of
the
shear
p la ne w ith
a resul tant
increase in the shear area of
the
bolt
shank.
The
t es t s
of
jo in ts
with these
bol ts
are
summarized
in
Table
5b .
The deformation of a
bol t
and
the
plates of jo in t SH3
are shown in Fig. 21.
In
both
cases fai lure
occurred
when the head
end
of one
of the two
top bol ts sheared
off .
The
average bol t
shear
s tress a t ultimate
was
about
lower in both joints than
was
predicted
from
the
s lotted
hole shear
j ig t es t s The sawed
sect ion
of jo in t SH3 shown in Fig. shows
the
deformation
of the bolts and of t he e nclo se d plate
t ca n
thus
be concluded that
slot ted holes in
the
enclosed
plates of
a
bolted joint
do
not reduce the ult imate strength of
ei ther
the
plates or the
bolts
in shear.
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30
SU RY
On the basis of this
study
the following conclus ions
have
been
reached:
1. One in.A325 b ol ts i ns ta ll ed by the
turn of nut
method
in holes
with
1/4 in .
clearance
ach ieved ave rage p re10 ad s
2
above
the
required bolt tension. Washers
under
the
turned
element
are
recommended to p revent s ev er e gall ing.
Bolts in sta lle d in h ole s w ith
5/16
in . clearance re-
quired.washers
under
both the head and the turned element
to
achieve
pre
loads
in
excess of the required bol t tension.
2. Oversize
or
slotted holes do no t great ly affect
the
losses
in
bol t
tension
with time following
ins t l l t ion Virtual ly
l l of the losses
occurred
within one week fter
ins t l l t ion
he loss in
tension
w s
about
8 of the in i t i l preload.
3. he s l ip
behavior of
joints
with
oversize
or slotted
holes
w s sim ilar to
the s l ip b eh av ior o f joints
with
holes of nom-
inal size. There w s
series
of small s l ips b efo re the jo int
went into bearing. he number of small slips
increased
as the
d istan ce o f s l ip
increased.
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31
4 he
average s l ip
coeff ic ient
for the joints
with
1/4
in
hole
clearance
w s
about
the
s me
as
the
s l ip
coefficient
for the control
joints he
joints
with
5/16 in clearance
holes
showed 7
decrease
in
th e
s l ip
coeff ic ient
he
s l ip coeff ic ient
for
s lot ted
hole
jo in ts
showed
22
to 33 decrease when
compared to normal
t e s t
specimens
5 Changes
in
bol t
tension
during
tes t ing
were
no t great ly
affected
by oversize
holes
or
s lo ts in
the
enclosed pl tes
All changes in
bol t tension
at major s l ip
were
w ith in the
previously observed range for change in
tension
at s l ip
6 Slotted
holes placed perpendicular
to
the l ine of load in
the
enclosed plates of
bolted
jo in t did
not re du ce
the
tensi le strength of
the plates or the shear
strength of
the bol ts
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T LES N FIGURES
3
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Test
Results
TABLE 1
Slip
Behavior
of All
Joints
-33-
Joint
Hole
Average
ni t i l
ni t i l
Slip
Diam
Bolt Bolt
Slip Coefficient
Elongation
Tension
Load
OH1 1 1-1/16 .0213
551.6 314.5
0.285
OHl 2
1-1/16
.0227
558.0
327.5
0.293
OHl 3
1-1/16
.0227
570.4
322.5
0.283
Average
0.287
OH2 1
1-1/4
.0178
522.8
274.5 0.263
OH2 2
1-1/4 .0119
422.0 242.5
0.290
OH2 3
1-1/4 .0132
474.5
295.0
0.312
Average
0.282
OH3
1-1/4 0143 495.2
286.5
0.290
OH3 2
1-1/4 .0139 482.5
267.0 0.277
OH3 3
1-1/4 .0135
473.5
260.0
0.274
Average
0.280
OH4 1
1-5/16
.0151
502.6
265.0
0.264
OH4 2
1-5/16
.0173 531.2
253.5
0.238
OH4 3
1-5/16
.0174 533.1 236.0
0.222
Average
0.245
SH1 1
Slotted
.0154
504.0
185.5
0.184
SHl 2
Parallel
.0162 524.1
199.0 0.190
SHl 3 to
l ine .0191 549.5 237.0 0.215
of
load)
Average
0.196
SH2 1
Slotted
.0223
573.9
248
0.237
SH2 2
Perpen-
.0230
574.5
220
0 192
SH2 3
dicu1ar
.0161
525.7 262.5
0.250
to
l ine
of
load)
Average
0.226
SH3 1
Slotted
.0223
568.5
225
0.200
SH3 2
Perpen-
.0232
475.4
210
0.221
SH3 3
dicular
.0250 480.2 214 0.223
to
l ine
Average
of
load)
0.215
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TABLE 2
Allowable
Hole Clearance for Different Hole Sizes
Bolt Proof
Min
Flat
Max
Hole Area
=
Max
Hole
Amount
Bearing
Size
Load
Area
Area /
e
Flat Area Min.
Area
Diam
Clearance
Pressure
1/2
12
.200 .601
0.401
11/16
3/16 62.6
5/8
19
.315 887
0.570 13/16
3/16 62.0
3/ 4
28
.465
1.227
0.761 15/16
3/16
62.5
7/8
39 .647
1.623
0.973
1 1/16
3/16
62.9
1
51 .846 2.074
1.224
1 1/4
1/4
72.0
1 1/8
56
.930
2.580 1.646
1 7/16 5/16
70.3
1 1/4
71
1.180 3.142 1.962
1 9/16
5/16
69.5
1 3/8
85
1.410 3.758 2.340 1 11/16
11
5/16
67.0
1 1/2 103
1.
71
4.430
2.713 1 13/16
5/16
66.9
The
area of
a
ci rcle with
a
d iameter equal to t he w id th across th e
f l ts
I
W
-
I
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l;ABLE
3
Loss in Tension of Bolts I nst alle d in Joints
35
Joint
Average
Loss
in Bolt Tension
1 Min.
5 Mins.
1
Hr
1
Day
1
Week
4 Weeks
OH1 1
1.21
1.69
3.10
4 121
4 2Si
5 52
OHl 2
1.33
1
7 io 2 16i
66io
3 Si
5 3 i
OH2 1
1
6 io
2 43i
3.00 4.22
4.6S
6 lSi
OH4 1
3.1S
3 34i
3.347.
3 34i 3 34
i
3.34
SHl 2
4.4S
4.90
5.07
5.45 5.5S7.
6.94
SH2 3
3 34
i
4 3i
4.52
4.52
4.527.
5.72
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T LE
4
R esults o f
th e
Load
Cell Studies on Single Bolts
-36-
Hole
ni t i l
Loss
in
Tension,
Kips
Clearance
Bolt
in.
Tension,
Min 5 Min
Hr.
Day Week
Kips
Bolt
Cell
Bolt Cell
Bolt
Cell Bolt
Cell
Bolt Cell
1/16 in . Std
60.0
1.0
0.6
1.3
1.4
1.3
1.9
1.3
2.5
1.3
2.6
1/4 in .
59.5
0.8
0.4
1.3 0.9
1.6
1.3
2.0
1.4
2.3
1.4
5/16
in .
60.7
0.7
0.2
1.1
0.4
1.5 0.6
1.5
0.8
1.5 0.9
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T LE
5
Test Results
Bearing
Joints
a
Plate Failure Tests
37
Joint
Net
Plate
Ultimate
Ultimate
Coupon
Area
Load Tensile
Stress
Ultimate
Tensile Stress
in
2
Kips
Ksi
SH2 l
12 46 820
65 9
61 6
SH2 2
12 42
854
68 6
62 5
SH2 3
12 42
852
68 5
62 0
10
SH3 l
17 37
1104
63 6
61 6
b
Bolt
Failure
Tests
Joint
Net Bolt
Ultimate
Apparent
Shear J ig
Shear
Area
Load Avg
Ultimate
Ultimate
Shear
:>tress
Shear Stress
in
2
Kips
Ksi
Ksi
SH3 2
12 56
1000
79 6
83 8
SH3 3
12 56
1006
80 0
83 8
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4
Required
Bolt
Tensfon
3
ONE
MINUTE
BOLT
LOAD
KIPS
1
38
Washer
Under Nut
o
No
Washer
Ot L.. O
L.. O _
13
16
13
16
3
II I
HOLE DIAMETERS
Reg semi fin. hex head
3
11
bolts
and heavy nuts
FIG 1 Effect of Hole Size
mn
Bolt
Tension Induced
by
Turn of Nut
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I
W
I
-t
-+
4
' ;='
I
-
f 4
I
I
I
2
..
I
l
w
4
39
w
4 =
-
4
:
l
:
I
1
I
I
I
I :
•
I
I
:
I
I
I
I
......
-
i I :
I
l l
:
I
I
I
I
----
I A325 Bolts
I A 36
SERIES
NO
HOLE
WIDTH
TESTED
DIA.
W
II
OHI 3
6 40
OH2
3
6 78
OH3
3
I
6 78
OH4
3
1 5 ~ 6
6 65
FIG. 2. Oversize/Hole rest Specimens
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40
I
I:
I
I....
....
-
I
0
I
v
•
I
-
-
I J .... J
I
A 6 It
A 5
Bolts
3 @ 5
4 =1 -3
3
/4
I
I :
I :
l I
II I
I
I
jo..
I I
I
l : I
: I
:
: I
I
I
I
I ~
Detail of Slot
Series SH I
FIG 3 Test Specimens
- Slotted Holes r lle l to the
Line of
Load
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4 1
w
W
2
t
W
4
3
a
5
4
II = 1
1
3
3
4 II
-I
l :
i
I
: I I
:
I I I
: I
:
i
i
I
i
I I I
A 5 Bolts
SERIES
NO WIDTH
An As
TESTED
W
II
SH 3
11 42
1 00
SH
3 13 68
1 36
FIG 4 Test Specimens Slotted
Holes
Perpendicular
to
the Line of Load
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42
III A325 Bolt
11
6
BOLT
TENSION,
KIPS
2
1 2 0
ELONGATION IN
0.001 0.002 3
STRAIN GAGE READING lN/IN
FIG. 5
Calibration of
Gaged
Bolts
e 9
1
Go ad
Bolt
FIG. 6 Location of Gaged
Bolts in Joint
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IG
olt in oad
ell
4
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44
8
6
Required
Preload·
Maximum Bolt Tension
Mean Bolt Tension
Minimum Bolt Tension
4
BOLT
TENSION
KIPS
OH4
SHI SH SH3
5 16
Parallel Transverse
Slots
Slots
None
one one
in 3 joints
OH3OH2
OHI
- - - - ' - - - - ' -_ . . . . I . . . - - - -L. . ._ . - - . . . . I . . . - - - - - 'L. . . . - . - - - - ' - - - - - ' ' ' - - - - -L. . . - - -L_. . . . I . . . - - - I -
Series
Hole
Clearance
Washers None one ne Two
Each
bar
represents
bolts
FIG The Range of
Bolt
Tensions
for
a l l Jo in ts Tested
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-45-
IG
a
Galling of
Plate
Under Turned Element Joint OHl-2
IG 9 b
Depression
Under
Bolt
Head
Joint OHl-2
1/16-in.
Clearance
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46
FIG 10 a Depression
Under
Bolt
Head
Joint
OH2
FIG b
Severe Galling of
Plate Under
Turned Element
Joint
OH2
1/4-in. Clearance, No
Washer
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IG
7
Plate
Area Under
Turned Element
Where a Washer
s
Used Join t OH3
1/4-in. Clearance
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48
FIG
epression Under
olt Head
Join t
OH4
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49
6
6
BOLT
TENSION
KIPS
I
Min
Min I
Hr
LOG
TIME
I
Day
I
Wk Wk 4Wk
FIG
Time Tension
Relationship
of Bolt
XB 9
in Joint
OHl
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JOINT
LOAD,
KIPS
300
200
100
r r
Slip
50
d
300
0 02 0 04
0 06
JOINT SLIP IN
0 08
0 10
JOINT
LOAD,
KIPS
200
100
J
r
•
26
1
•
J
,
o
0 02 0 04 0 06
JOINT ELONGATION IN
0 08
0 10
Join t
Slip
and
Elongation
of
Joint OH4 3
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25
2
_[Ini t io I
Slip
LOAD
r
r
[
IPS
15
5
1
2 3
4
5
6
7
SLIP
IN H S
I
V
FIG
Load Slip Diagram of Joint
SH1 l
t
I
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-52-
FIG.
Faying
Surface Damage of
O
Join t
1/4- in . Clearance
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53 ·
o Results of
Tests
Nester
• Results of OHI Series Tests
• Results of
Oversize and
Slotted
Hole Tests
4
3
2
~ e r a g e of 6 Joints
K V e r ag e
of O Joints
0.1
Il _
Oversize Holes
Slotted Holes
Series
Hole
Clearance
OHI
I/
16
OH2 OH3
OH SHI
516 Parallel
Slots
SH SH3
Perpendicular
Slots
FIG
Comparison
of
Average
S l ip oe ff ic ie n ts
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54
700
600
500
JOINT
LOAD
400
KIPS
6 ~ 4
300
Joint SH2-3
200
100
0 1 0 2 0.3
0.4
700
600
500
JOINT
400
LOAD
KIPS
300
200
Joint SH2-3
100
46
Q
o
0 1 0 2 0.3
ELONGATION IN
0.4
FIG
18
Load Jo in t Elonga tion
and Load Specimen
Elongation
of Joint SH2 3
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FIG
e fo rmat ion o f Slotted oles
55
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t
....
/ / ~
-
I
r T
/
1
ound ole
5 6
t
h
1
7 / /
/ / / 7
.
Slotted ole
FIG
20 Comparison of Bolt and Plate Deformations
FIG
21 Deformed Plates
Bolt
in Sawed
Section of
Joint SH3 2
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FIG
Sawed ection
of
oint SH3
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7. REFERENCES
1. Research Council
on Riveted and Bolted Structural
Joints of
th e Engineering
Foundation.
SPECIFICATIONS FOR STRUCTURAL JOINTS USING ASTM A325
OR
A490
BOLTS, September, 1966
2.
OUT
OF
PLUMB
TILT STRAIGHTENS
BANK
Engineering News
Record,
Vol. 178,
No.9 ,
March
2,
1967,
pp. 33-35
3. Wilson, W M., and Thomas, F. P.
FATIGUE TESTS ON RIVETED JOINTS , Bulletin
No.
302,
University of I l l inois Engineering Experiment Station,
1938
4. Hoyer, W.
UBER GLEITFESTE
SCHRAUBENVERBINDUNGEN
3 . BERICHT)
HOCHFESTE SCHRAUBEN MIT VERSCHIEDENEM
LOCHSPIEL
ON
SLIDE
PROOF
BOLTED CONNECTIONS 3RD.
REPORT) HIGH-STRENGTH
BOLTS WITH
DIFFERENT
HOLE CLEARANCE), WISSENCHAFFLICHE
ZEITSCHRIFT
DER HOCHSCHULE
FUR
B UWESEN
COTTBUS,
3,
1959-1960 , Heft 1,
pp.
49-53
5.
Chesson, E., Jr and Munse, W.
H.
STUDIES ON
THE BEHAVIOR
OF HIGH-STRENGTH
BOLTS
ND
BOLTED
JOINTS, Bulletin No. 469, Vol. 62, No. 26, Univers ity of
Ill inois
Engineering Experiment Station, University of
I l l inois,
Urbana,
I l l inois,
October, 1964
6. Steinhardt, 0 and Mohler, K.
VERSUCHE
ZUR NWENDUNG VORGE
SPANNTER SCHRAUBEN
1M
STAHLBAU,
I
TElL TESTS ON THE APPLICATION OF HIGH-STRENGTH BOLTS
IN
STEEL CONSTURCTION,)
Part
1,
Berichte
des Deutschen
Ausschusses
for Shahlbau, Stahlbau-Verlags, GmbH, Cologne, 1954 Heft
r 18.
7. Aurnhammer, G.
HV-VERBINDUNGEN. UBERLEGUNGEN, BETRACHTUNGEN,
VERSUCHE
HIGH-STRENGTH
BOLTED
JOINTS, THOUGHTS, OBSERVATIONS, TESTS).
Preliminary Publication,
Seventh Congress,
IABSE,
Rio de
Janeiro, 1964,
pp.
415-430
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8. Steinhardt,. O.
THE GERM N CONTRIBUTION TO RESEARCH JUBILLEE SYMPOSIUM
ON HIGH STRENGTH BOLTS
The
Insti tution
of
Structural
Engineers, London
June,
1959 pp. 2-9
9.
Denkhaus
H.
G.
STRENGTH
OF
WASHERS The National Mechanical Engineering
Research Insti tute,
CSIR
Contract No.
CN378
Council
for
Scientific and Industrial Research, Pretoria, South Africa,
February, 1961
10.
Tajima,
J.
EFFECT OF RELAXATION N CREEP ON
THE
SLIP LO OF
THE
HIGH-
STRENGTH BOLTED JOINTS Structural
Design Office, Japanese
National Railways,
Tokyo
June,
1964
11. Waltermire, W. G.
EVALUATING FASTENER N JOINT PERFORMANCE WITH A LO ANALYZER
Assembly and
Fastener
Engineering,
January
1962
pp . 33-35
12.
Stevin Laboratory
DECREASE
OF
THE PRE LOAD IN HIGH STRENGTH BOLTS IN
THE
COURSE
OF
TIME Provisional Results ,
Department
of Civil Engineering,
Delft, The
Netherlands,
1965 C.E.A.C.M. X-65-l3
13.
Wallaert,
J. J Sterl ing,
G.
H.,
and
Fisher,
J. W.
WH T HAPPENS TO BOLT TENSION
IN
LARGE
JOINTS?
Fasteners,
Vol. 20
No.3 ,
1965 pp. 8-10
14. Nester, E. E.
INFLUENCE OF
VARIATION
OF THE CONTACT AREA UPON THE SLIP RE-
SISTANCE
OF A BOLTED JOINT M. S. Thesis, Fritz Engineering
Laboratory Report No. 318.1, July, 1966
15. Foreman R. T., and Rumpf
J.
L.
STATIC TENSION TESTS OF
COMPACT
BOLTED JOINTS Journ al o f
th e Structural Division, ASCE Vol. 86, No. ST6 Proc.
Paper
2523
June,
1960
16. Chiang, K. C., and Vasarhelyi,
D.
D.
THE
COEFFICIENT
OF
FRICTION IN
BOLTED JOINTS
M E
WITH
VARIOUS
STEELS
N WITH MULTIPLE CONTACT
SURFACES
University of
Washington,
Seatt le, 1964
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17.
Upton K
A.
n Cullimore M G
THE DISTRIBUTION OF
PRESSURE
BETWEEN W FLAT PLATES· BOLTED
TOGETHER
International
Journal
of
Mechanical
Sciences
Vol.
6 No.1
Feb. 1964 pp. 13 27