strength of a440 steel joints connected with a325 bolts publicat
TRANSCRIPT
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
1/52
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
2/52
STRENGTH OF A44 STEEL JOINTSFASTENED WITH A325 BOLTS
by
John W Fisher
PaulO Ramseier
Lynn S Beedle
This work has been car r ied our as par tof the p ro je ct on Large Bolted Connections s p ~sored f inanc ia l ly by the Pennsylvania Departmentof Highways the Department of Commerce Bureauof Public Roads and the American Ins t i tu t e ofStee l Construction Technical guidance pro-vided by the Resea rch Counc il on Riveted andBolted S tr uc tu ra l J o in ts .
. Fr i t z Enginee ring LaboratoryDepartment of Civi l Engineering
Lehigh Universi tyBethlehem Penasy1vania
Apri l 1963
Fr i t z Engineer ing Labora to ry Report No 288 4 .
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
3/52
STRENGTH OF A440 STEEL JOINTSFASTENED WITH A3 5 BOLTS
by
John W Fisher l P a u l a Ramseier 2 and Lynn S. Beedle 3
SYNOPSIS
Tests of s t ruc tu r a l j o in t s of A440 s t e e l connected
with A3 5 high-s t reng th bol t s i n s t a l l ed by the tu rn -of -nu t
method were conducted to determine t he i r s l i p res i s tance an d
u lt im a te s tr en g th . The purpose of the program was to e s ta -b l i sh an approximate shear s t r e s s value for bear ing- type con-
nect ions an d to determine th e i nf lu en ce of j o i n t length on the
ul t imate s t reng th of higher s t reng th s t e e l connections. Eleven
of the j o in t s t e s ted had two l i ne s of fas teners ranging from
4 t o 16 fas teners in l ine. . Other j o in t s had four and s ix
l i ne s of fas teners .
The ul t imate s t reag th of the j o i n t s with th e th eo re -.
t i c a l l y pred ic ted values based on t he n on -l in ea r behavior of
the component pa r t s shows good cor re la t ion between the th eo re-
t i c a l ana lys i s and the t e s t r e s u l t s These s tud ies together
with the e a r l i e r work with s t ruc tu r a l grade s t e e l have aided
in the development of a r a t i ona l bas i s fo r design
1 Research Associa te Fr i t z Engineering Laboratory LehighUnivers i ty Bethlehem e n n s y l v a n i a ~
2 Dipl . Ing. ETij Wartmann Cie. A.G. Brugg Switzerland;formerly Research Ass is tan t F r i t z Engineer ing Labora to ryLehigh Univers i ty Bethlehem Pennsylvania.
3 P ro fes so r o f Civ i l Engineering an d Direc to r of Fr i t z n g i n ~
eer ing Laboratory Lehigh Univers i ty Bethlehem Pennsylvania.
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
4/52
288.4
1 . INTRODUCTION
-2-
A pp lic atio ns o f h igh-s t r eng th bol t s have been e x p n ~
considerably s ince the R es ea rc h C ou nc il on ~ i v e t e and Bolted
S tr uc tu ra l J o in t s adopted i t s spec i f i ca t ion fo r bol ted j o i n t s in
1960 1 . One of the most important provis ions of t h i s spe c i f i
cat ion was the change in the a ll ow ab le s he ar s t r e s s fo r bear ing
t yp e c on ne ct io ns . This al lows the subs t i tu t ion of two bo l t s fo r
th ree r i v e t s The experimental and theore t i ca l research s tud ies
on which these design ru les were based considered only connec
t ions fabr ica ted with STM s t e e l
The in cr ea se d u se in r ecen t years of high s t reng th
s t ee l fo r const ruct ion p urp os es h as c rea ted a need fo r rese arc h
to i n v e s t i g a t e the be hav ior o f these s t ee l s when used in con
nect ions fabr ica ted with A3 5 h igh-s t r eng th bo l t s . With the
higher yie ld s t r e s s l eve l the o v e r a l l behavior of connections
made with STM A44 s t e e l may i f f e r from the behavior of con
nect ions made with STM s t e e l
A grea t deal of information has been obtained on the
behavior o f c on ne ct io ns using s t e e l in previous research
programs 2,3 . With t h i s i nf or ma ti on a s background mater ia l ,
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
5/52
288.4
i t was the purpose of the present work to study:
1 . The basic behavior of ST A44 s t e e lconnected with ST A3 5 bo l t s ;
2. The appropr ia te shear s t r e s s to beused in compact j o i n t s
3. The poss ible re du ctio n o f shear s t rengthassocia ted with long connect ions of t h i smater ia l ;
4 . The e ff ec t of i n t e rna l l a t e r a l forcescaused by p l a t e necking near th e u l t i -mate s t rength of th e j o i n t and
5. ny e ff ec t on the behavior of the j o i n tcaused by the presence or absence ofwashers .
In addi t ion to the la rg e sca le t e s t s the behavior
3
of the ind iv idua l elements of a j o i n t was establ ished in t h i s
s tudy. The proper t i e s of the p l a t e mater ia l and the bo l t s
were determined from p l a t e coupon t e s t s p l at e c a li br at io n
t e s t s di rec t t ens ion and torqued tens ion t e s t s of the bo l t
an d double shear t e s t s of the b o l t s . A t h eo re t i c a l ana lys i s
was made to predic t the ul t imate s t reng ths of th e connect ions
t e s t ed .
Very l i t t l e previous research has been car r ied out
on l a rge bol ted bearing type connect ions using high s t r eng th
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
6/52
288.4 -4 -
s t e e l s In 957 a demonstrat ion t e s t of a compact A 4 high
s t rength s t e e l specimen connected by nine A3 5 an d nine A 5 BD
bol t s was performed a t Northwestern Univers i ty 4 . The j o i n t
was e s ~ g n ein such a way th a t p la te f a i l u r e occurred. Other
t e s t s of small specimens were conducted a t the same Universi ty
in c on ne ct io n w it h a fa t igue t e s t program 5 .
2. DESCRIPTION OF TEST SPECIMENS
1 . Pi lo t Tests
Six compact j o in t s were t e s ted to determine the appro
pr i a t e shear s t r e s s fo r such j o i n t s Each specimen was one ha l f
of a double shear bu t t j o i n t as shown in Table 1 . These t e s t s
were designed to determine the u lt im a te s tr en g th of the fas ten
ers in shear t h a t would develop the t ens i l e capaci ty of the ne t
sec t ion of the main m t e r i l ~Coupon t e s t s had establ ished the
ul t imate t ens i l e s t reng th as approximately 75 k s i the shear
s t rength of a s ingle bo l t was found to be approximately 85 k s i
an d therefore th e re qu ir ed shea+ area of fas teners would seem
to be only s l i gh t l y l e ss than the net p la t e area . The p i l o t
t e s t s also were conducted to determine i f var ia t ions in th e n e t
p l a t e area had an y inf luence on the shear s t reng th of bo l t s in
a j o i n t In add i t ion , a study was made of the e ff ec t the
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
7/52
288.4
presence or absence of w ashers h ad on the behavior of these
j o i n t s
In previou inves t iga t ions of r ive ted and bol ted
j o in t s (2 ,3 ,6 ) the concept of tension-shear r t ~ (T:S) a t
balanced desi&n has f igured prominently in determining
allowable s t r e s ses . s .discussed in Ref. 7, i t i s l ike ly
tha t t h i s concept i s not appl icab le in general to mater ia l s
o t h e ~than s t e e l used in r e l a t ive ly shor t j o i n t s None-
the less , f o ~ reference purposes the T:S r t ~ sare shown in
the t ab le s . s ind ica ted in Table 1 t he t en si on -s he ar r a t i o-
used in these t e s t s ranged from 1:1 .10 to 1:0 .90 .
-5 -
The di ffe rence in behavior of j o i n t s fabricated with
regular head bol t s with the 1960 ASA 8 s tandard thread and of
j o i n t s fabr ica ted with heavy head bol t s with the shor te r thread
length was a ls o s tu die d. In a l l j o i n t s th e sh ea rin g planes
p as se d th ro ug h the shank port ion of the b o l t s .
The f i r s t four j o i n t s E4la, E4lb, E4lc, an d E4le
consis ted of two l ines of four 7/8- inch diameter A325 regular
head bo l t s . The shear area to t e p s i l e area r a t i o for these
specimens was varied from 1 to 0.90 to 1 to 1.10 by varying
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
8/52
i
288.4
the pla te widths in the j o i n t s Each regu la r head bo l t in
these four j o i n t s was p ro vid ed w it h one washer under th e head
and on e under the nut .
Jo in t s E41f an d E41g were fabr icated in the same
-6-
manner and from the same p l a t e mater ia l used fo r the other four
j o i n t s Heavy head bol t s were i n s t a l l ed in these two j o i n t s
ins tead of regular head bo l t s . The number o f washers also
d i ffe red from the number used in the f i r s t four specimens.
J o i n t E41f was p ro vi de d w it h a washer under th e nut only and
j o i n t E41g had no washers under head or nut .
The t e s t specimens fo r the p i l o t s e r i e s were pro-
por t ioned so t h a t a t ul t ima te load the shear s t rength of th e
fas teners was near ly equal to th e t e n s i l e capaci ty of the net
sec t ion . Hence,
where n = ne t t e n s i l e area
s = bo l t shear area
1 )
a n = s t r e s s on the net sec t ion (u l t imate) shear s t rength of the bol t (u l t imate)
When the ul t ima te loads 9-re balanced
f n
C tT= -S
( tens ion-shear r a t i o (2)
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
9/52
288.4
For two l i n e s of four 7/8 inch bol t s with l5 / l6 inch d r i l l e d
holes a main pla te th ickness of inches and two shear
planes the p l a t e width changed from 6.20 to 7.16 inches as
the r a t i o Tis was var ied from 0.90 to 1.10.
2. Long Jo in t s
Each of tl; e long j o in t s had two l ines of 7/8 inch
A3 5 heavy head bol t s with a pi tch of 3.5 inches . ~ c hbo l t
had a washer under the nut only. The number of bo l t s i n l i n e
var ied from j o i n t to j o i n t from four to s ix teen .
Based on re su l t s obta ined from t ~ p i l o t t ~ s t s these
subsequent t e s t specimens were propor t ioned by provid ing a net
p l a t e area equal to the shear area of the bo l t s . Since th e
shear area in a j o i n t i s dependent upon the number of b o l t s
the shear area var ied for the long j o i n t s . In order to main-
t a in equal i ty between shear an d tens ion areas i t was necessary
to vary the net area of the j 9 i n t . This was accomplished
by varying the width an d the th ickness of the p l a t e m a ~ e r i a lAs
the number of 7/8 inch bol t s in l i ne var ied from 4 to 10 the
p l a t e width var ied from 6.68 to 13.88 inch es w ith a 4 inch
gr ip . In the case of the j o i n t s having 13 to 6 bol t s in
l i n e the p l a t e width var ied from 9.70 to 11.50 in ches w ith
an 8 inch gr ip . Table out l ines the nominal dimensions fo r
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
10/52
288.4
these specimens.
8-
3. Wide Jo in t s
The th ree specimens in t h i s group to study the e ff ec t
of j o i n t width were designed and fabr icated as described pre
viously. Heavy head 7/8- inch A 5 bol t s were used with a
washer under the nut only .
Jo in t E46 was the same as j o i n t E4 l in the long
j o in t s e r i e s except t ha t the number of l ines of bol t s and
the p l a t e w ~ t were th ree t imes as grea t .
Jo in t E74 was i d en t i c a l to j o i n t E7l except tha t i t
ha d twice the number of l ines of bo l t s an d was twice as wide.
Because of premature f a i l u r e of the main pla te outs ide the
j o i n t in t ~ specimen another j o i n t was fabr icated an d t e s t ed .
This dupl ica te of j o i n t E74 was ca l led E74l. Table 3 out l ines
the nominal dimensions of the specimens E46 E74 and E74l.
3. MATERIAL PROPERTIES
1. Pla tes
The pla te fo r l l j o in t s in t h i s se r i e s of t s t s was
ASTM A44 s t ruc tu r a l s t e e l cut from Universal Mill s t r i p s 8 or
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
11/52
288.4 9
26 inches wide by 1 inch th ick an d approximately 36 f t long.
w d i f f e r en t heats of s t ee l were used one fo r the p i l o t
invest igat ion and one for the other t e s t s
At leas t two pla te coupons were cu t from the mate r i a l
of each j o i n t t e s t ed . These coupons were 1 inch th ick an d
were milled to ~ inches in width. Table 4 gives a complete
summary of a l l coupon proper t ies and l i s t s mean values and
corresponding standard dev ia t ions .
A typ ica l s t r e s s s t r a i n diagram i s shown in Fig . 1.
The i n i t i a l por t ion as determined from an autographic s t r a i n
recorder i s shown expanded an d the complete curve as measured
with ca l iper i s a l so shown
In a l l t e s t s both the yie ld s t r e s s and the s t a t i c
yie ld s t r e s s l eve l s were recorded. The yie ld s t r e s s l e v e l i s
repor ted for a s t r a in off se t of 0 2 The s t a t i c yie ld s t r e s s
l eve l fo r each coupon was taken as t h ~ mean of the minimum
values as shown in Fig. 1. Standard devia t ions are a lso shown
in Table 4 and in order to determine whether or not the re was
a s i gn i f i c an t di ffe rence between the means fo r the yie ld s t r e s s
levels an d the ul t imate s t reng ths of the d i f f e r en t hea t s the
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
12/52
288.4 -10-
t t e s t fo r a f ive percent l eve l of s ignif icance was appl ied 9) .
There were no s ign i f i c an t di ffe rences found in the y i e l d s t r e s s
l eve l s or u lt im a te s tr en g th s of the two h ea ts of mater ia l .
This also i s confirmed by a visua l inspect ion of th e means an d
standard devia t ions l i s t e in Table 4 . The p la t e mater ia l was
purposely o rd ere d n ea r the minimum requirements spec i f i ed by
ST fo r A440 s t e e l
In order to s t ~ l i s hth e behavior of the p la te e le -
ments, spec ia l p l a t e ca l ib ra t ion t e s t s were conducted by t e s t -
ing a p l a t e of the same mater ia l used in the la rge j o i n t s
The p l a t e ha d a width equal to th e gage dis tance, a thickness
of 1 inch, and two holes r i l l e 3.5 inches on center as shown
in the i n se t in Fig. 2. The tens ion-elongat ion re la t ionsh ip
was recorded fo r the mate r i a l with th e d is ta nc e between th e
ho le -cen te r s as gage l eng th , which was equal to the pi tch
length in the large j o i n t s The load-elongation curves fo r
these t e s t s a re shown in Fig. 2. These curves a re es sen t i a l
to the t h eo re t i c a l pred ic t ion of the u lt im a te s tr en g th of the
bol ted j o in t s
2. Bolts
The bol t s were 7/8- inch ST A325 bo l t s . The length
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
13/52
288.4 11
of the b o l t under the head var ied from 5.25 to 9.5 inches . A ll
b o l t s were the heavy head type with shor t thread length except
fo r the bol t s in four of the p i l o t t e s t s in which regu la r head
bol t s were used. The th re ad le ng th s are l i s t e in Table 5 .
Each bol t l o t was ca l ib ra ted according to the procedures
descr ibed in Ref. 10 to determine i t s d i r ec t tension and torqued
tension b e h v i o ~ br i e f summary fo r each l o t i s given in
Table 5.
Bol t shear t e s t s were conducted to e s t ab l i sh the
re la t ionsh ip between the shearing load car r ied by a s ing le
bo l t an d i t s deformation. Two d i f f e r en t types of t e s t s were
conducted as ind ica ted by the sketches in Fig. 3. In one type
the b o l t s were subjec ted to double shear by pla tes loaded in
tens ion and in the o the r t e s t the bo l t s were subjec ted to
double shear by applying a compression load to the p la t e s .
The pla tes were fabr icated from the same mater ia l and had the
same gr ip length as the corresponding assembled j o i n t s Three
bo l t s were t e s ted from each l o t in each type of t e s t The
re su l t s of the t e s t s of the l o t bo l t s a re given in Fig.
The shear s t rength of s ing le b ol ts te ste d in pla tes
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
14/52
288.4 12
loaded in tens ion was approximately 1 l e s s than the s ~ r
s t r eng th from the compression t e s t When bol t s are loaded by
pla tes in tens ion the bearing condi t ion near the s hear plane s
causes a prying act ion and r e su l t s in an add i t iona l t e n s i l e
component which reduces the b o l t shear s t reng th . The catenary
act ion resu l t ing from the deformations may also con t r ibu te to
the t en s i l e component. In addi t ion to reducing the b o l t shear
s t rength some reduct ion in the deformation capaci ty i s also
apparent . When bol t s a re loaded by pla tes in compression i t
simulates th e c on ditio n of bol t s in the i n t e r i o r of j o i n t s as
the prying act ion i s minimized.
4. FABRICATION OF TEST O NTS
1 . Fabr ica t ion
A ll shop work necessary fo r the fabr ica t ion of the t e s t
j o in t s was done by a loca l f a b r i c a t o r. The shop procedure was
the same for l l specimens. Pla tes were f i r s t cu t by torch and
then machined to the f i na l dimensions. Loose m il l sc a le was
removed by hand brushing with a wire brush. O il and grease
were wiped from the pla tes in order to es tab l i sh a faying sur-
face condi t ion which would preva i l in f i e l d assembly.
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
15/52
288.4 13
For the wider j o i n t s i t was necessary to reduce
s l i gh t l y the .width a t the ends in order to grip the specimens
in the t e s t i ng machine. This was done with a to rch in tpe
s e ~ of Jo in t E an d E7 Special a t t en t i on to t h i s t r a n -
s i t i o n was giv en with Jo in t E74l where a l l edges were ground
to a smooth t r ans i t i on a f t e r the rough burning.
The pla tes fo r each j o i n t were assembled in to a
genera l j o in t conf igura t ion and then clamped together. The
four co rne r h ole s were subdr i l led an d reamed fo r alignment.
Pins machined to f i t the reamed holes were inse r ted to hold
the j o i n t in al ignment while the remainder of the holes were
d r i l l e d through a l l p l i e s of the j o i n t A ll holes were d r i l l e d
l 5 / l 6 i nch in diameter to al low l /16 inch clearance fo r the
7/8 inch b o l t s .
2. Assembly
The b o lt in g u p o pe ra ti on was ca r r i ed out a t th e r i t z
Engineering Laboratory by a f i e l d erec t ion crew of the f ab r i -
c a to r. This arrangement made i t poss ible to gather informat ion
concerning the bo l t t ens ion .
With a few exceptions the bo l t s were snugged with
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
16/52
288.4 -14-
th e impact wrench and then given a prescr ibed ro t a t i on depend
ing upon th e bo l t diameter an d grip 1ength 1 . A ll bo l t s in
j o i n t E4 b and four bo l ts in j o i n t E74 were i n s t a l l ed with
a hand torque wrench and t ightened to the corresponding aver
age b o l t elongat ion. The diameter of l l bo l t s used was
7/8- inch an d ~ grip was 4 inches fo r l l the j o i n t s except
two in the long ser ies E 3 and E161 .
Complete records of bo l t elongations were kept fo r
each b o l t in every j o i n t of th e t e s t se r i e s . The i n i t i l
length was measured some t ime before t he b ol ti ng -u p operat ion.
The f ina l length was measured f t e r i n s t l l t i o n
5. INSTRUMENT TION
The ins t rumenta t ion fo r l l of the t e s t specimens
was essen t ia l ly the same except fo r j o i n t s having more than
two l ines of bo l t s . Figure 4 shows j o i n t E74 in the t e s t i ng
machine with ins t rumenta t ion at tached. Included were SR
s t r a in gages, a mechanical extensometer and d ia l gages. Follow
ing i s a shor t descr ipt ion of the purpose of these gages and
measuring devices .
SR e l e c t r i c l r e s i s t ance s t r i n gages were genera l ly
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
17/52
288.4 15
attached only to the edges of th e main and lap p la t e s . These
gages were used to d e tec t eccen t r ic i ty due to improper gripping
and to pick up the onset of yie lding of the gross sect ion.
Addit ional gages were attached to the faces and dead end of
the lap p l a t e of wide j o in t s E an d E7 in o ~ r to study
the e ff ec t of any i n t e rna l l t e r l forces caused by p la t e
necking near ul t ima te load.
For j o i n t E74l four bo l t s were prepared ea ch h av in g
two SR s t r i n gages at tached to the bo l t shank near the bo l t
head to d e tec t changes in the bo l t tens ion during t e s t i n g of
the j o i n t s During i n s t l l t i o n of these bo l t s s t r i n readings
were taken and r e l a t ed to ca l i b r a t i on t e s t s conducted on the
same type of bo l t s so t ha t th e i n i t i l bo l t tens ion was known
The e lo ng at io n o f each pi tch of the j o i n t was measured
along th e edges of the pla tes with a mechanical extensometer.
These measurements were used to check the accuracy of the
t h eo r e t i c a l s olu tio n fo r the load p a r t i t i o n and u lt im a te s tr en g th
of the bol ted j o i n t s
During the t e s t s of j o i n t s E 6 and E7 the mechanical
extensometer was used t o ~ e o r dt he t ra ns ve rs e and long i tud ina l
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
18/52
288.4 -16-
p l a t e deformations between bol t s of one of the lap p la t e s .
he t r ansverse measurements gave some indicat ion of th e
forces du e to p la t e necking. he long i tud ina l measurements
w er e c omp are d with the pi tch measurements made on the edges of
the p la t e s .
Dial gages 0.001 i n . were used to measure the
over-a l l e lo ng at io n o f the j o i n t an d provide con t ro l during
the t e s t i ng opera t ion . ore s ens i t i ve gages 0.0001 i n .
were used to measure the s l i p between the lap and main p l a t e s
as well as the r e l a t i ve displacement between p l i e s of mater ia l
making up th e lap an d main pla tes of j o i n t s E13l and E16l.
6. TEST PRO E URE
he j o i n t s were loaded in s t a t i c tens ion by a
5 00 0 0 0 0- lb . h y dr au li c t e s t ing machine using wedge g r i p s .
he specimen was gr ipped an d t e s t i ng proceeded in equal load
increments u n t i l major s l i p occurred . Very c lose observation
of the d ia l gages as the expected s l i p load was approached
made i t poss ib le to record the displacement a t the i n s t a n t
p r i o r to the occurrence of s l i p . After s l i p load was again
appl ied in e qu al in cre me nt s u n t i l major yie lding of the p la t e
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
19/52
288.4 -17-
mater ia l occurred. In the i ne l a s t i c region, a f t e r applying
an increment of load the specimen was allowed to s t i l i z ~
a t a constant s t r a in value . The amount of addi t ional s t r a in
which took place during s t ab i l i za t i on of the load was small
as a t t e s t ed by d ia l gage readings . T hi s p ro ce du re was fol low
ed u n t i l f a i l u r e of th e j o i n t occurred. The load-deformation
re la t ionsh ip shown in Fig. was typ ica l fo r l l specimens.
In the longer jo in ts f ai lu re occurred when an end bo l t sheared.
All j o in t s with four b o lts in l i ne e xcept E4 la showed a
sudden and complete shearing of l l b o l t s .
7. T ST R SU TS
1 . Pi lo t Tests
A complete summary of the r e su l t s fo r the p i l o t t e s t
s e r i e s i s given in Table 1 . Jo in t E4la f a i l ed by a tear ing of
the main pla tes whereas l l other specimens ~ x p e r i e n e
simultaneous f a i l u r e of l l bo l t s .
All j o in t s experienced a sudden major s l i p as i nd i
cated for a typ ica l j o in t in Fig. 5 . This s l i p occurred a t a
nominal bo l t shear s t r e s s which var ied from 27.0 to 29.3 k s i
except fo r j o in t E4lb. Table shows l l t e s t da ta . In
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
20/52
288.4 -18-
j o i n t E4lb f i r s t major s l i p occurred a t a nominal bo l t shear
s t r e s s of 20.6 k s i This premature s l i p m y have occurred
because of warping of the j o i n t during bol t ing-up . The j o i n t
was bol ted-up by hand while ly ing in a horizonta l pos i t i on .
This resu l ted in a curvature out of the lo ad in g p la ne an d
evidently the eccentr ic loading condi t ion caused an e a r l i e r
s l i p A ll j o i n t s had t i gh t m ill sca le f ay ingsu r f ace s .
Fo r the f ive j o i n t s which f a i l ed by simultaneous
shearing of a l l bo l t s the nominal bo l t shear s t re s s a t f a i lu r e
var ied from 75.6 to 81.3 k s i Jo in t s E4lb E4lc an d E4le were
fabr icated from the same p la t e mater ia l an d connected by the
same l o t of bo l t s .
2. ong Jo in t s
complete summary of the r e su l t s fo r a l l th e long
j o in t s i s given in Table 2. Only j o i n t E4l f a i l ed because of
simultaneous shearing of a l l the bo l t s . In the other j o i n t s
one or more en d fas teners unbuttoned an d the j o i n t remained
i n t a c t The load a t which the f i r s t bo l t sheared has been con
s id ered th e f a i l u r e load even though complete rup tu re had not
occurred . s a check in the case of j o i n t ElOl load was re
applied u n t i l a second bo l t unbuttoned a t a s l i gh t l y lower
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
21/52
288 4 19
load The sequent ia l f a i l u r e of th e fas teners was s imi la r to
t ha t reported in Ref 3 for A s t e e l j o i n t s
Major s l i p occurred a t nominal bo l t shear s t r e s s e s
which var ied from 23 8 to 26 7 ksL as shown in Table 2
A ll of these j o i n t s f a i l ed by a shearin g o f one or
more bo l t s The average bo l t shear s t r e s s a t f a i lu r e var ied
from 75 7 to 66 2 k s i as the j o i n t length var ied from 10 5
to 52 5 inches in length 4 to 6 fas teners in l i n e
A visua l record o f d ef orm at io n of bo l t s along the
length of j o i n t E i s given in Fig 6 The high s t r e s s in
the pla tes a t the ends of th e j o i n t i s revealed by the l a rge r
elongat ion a t the end holes The prying ac t ion a t the lap
p la t e end i s revealed by th e s ep ara tio n of th e p la t e s Fig 7
shows j o i n t E10l a f t e r unbuttoning of both top bo l t s The
off se t of th e bo l t shank remaining in the j o i n t can be seen
The load deformation re la t ionsh ip for t h i s j o i n t was given in
Fig 5
3 Wide Jo in t s
The resu l t s of the three t e s t s on the wider j o i n t s
are summarized in Table 3 All j o in t s experienced a sudden
major s l i p
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
22/52
288 4 20
Jo in t E46 a compact wide j o i n t with 24 bo l t s in i t s
pa t te rn experienced f i r s t major s l i p a t a nominal bo l t shear
s t r e s s of 27 7 k s i No other minor s l i p s were observed the re -
a f t e r The ul t imate load was 218 kips
i r s t major s l i p occurred in j o i n t E74 a t a nominal
bol t shear s t r e s s of 27 1 k s i Severa l minor s l i p s were
recorded thereaf te r but produced no s ign i f i c an t e ff ec t s
Fai lu re occurred a t a load of 241 kips when on e bo l t un-
but toned
Jo in t E74l experienced f i r s t major s l i p a t a nominal
bo l t shear s t r e s s of 20 2 k s i Severa l minor s l i p s were
not iced thereaf te r u n t i l the j o i n t came in to f u l l bear ing
Fai lu re occurred when one of the corner bo l t s of the lap p la t e
end unbuttoned a t a load of 225 kips
8 N LYSIS OF R SULTS
1 Ultimate Strength
s expected a l l j o in t s with equal tens ion and shearing
areas fa i led by shearing of one or more bo l t s In j o in t s with
four rows of bol t s simultaneous shearing of a l l the bo l t s
occurred In the longer j o in t s one or more of the bo l t s in th e
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
23/52
288.4 -21-
lap p l a t e en d unbuttoned d ~ e to t h e i r l a rger deformations an d
the combined s t r e s s s t a t e
The re su l t s of the t e s t s are shown in Fig. 8 as so l id
dots where the u lt im a te s tr en g th of th e j o i n t s are represented
by an unbuttoning fac to r . Th e length of each j o i n t i s shown
both as ac tua l length an d in terms of th e number of pi tches
3 .5 i n
Because bol t s of severa l l o t s and s t reng ths were used,
i t i s convenient to rep resen t the average shearing s t r e s s a t
f a i l u r e in non-dimensional form. This non-d imens iona l quant i ty
i s cal led the unbuttoning factor U an d i s computed by div id -
ing the average ul t ima te shear s t r e s s of the j o i n t Lav as
given in Tables 1, 2 and 3 by the tension shear s t reng th of
a s ing le bol t ~ t as given in Table 5 .
U = t-av1:t
Thus,
3)
The unbuttoning fac to r U descr ibes , in e f f e c t , the
extent to which the b o l ts in a j o i n t a re able to r ed i s t r i bu t e
fo rces . I f i t was equal to uni ty then a l l fas teners would
carry an equal share of the load a t ul t ima te j u s t l i ke a
s in g le f as te n er.
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
24/52
288.4 -22-
In Fig . 8, a decrease in the unbuttoning fac to r can
be seen as between the compact and the longer j o i n t s However
th i s decrease i s a t a decreasing r a t e an d appears to approach
an asymptotk value of approximately 0.80 . For j o i n t lengths
g r e a t e r than 2 inches the average shear s t r e s s of the bol t s
in the j o i n t a t f a i l u r e was about 8 of the shear s t r eng th of
a s in gl e f as te ne r.
The t e s t r e su l t s a re compared with the t h e o r e t i c a l
so lu tio n in Fig. 8, the l a t t e r being shown by a dashed l i n e
The u lt im a te s tr en g th of the t e s t j o i n t s was computed with the
equil ibrium an d c o m p a ti b il it y c o n di ti o ns formulated in Ref. 11.
t i s a met ho d w hi ch i s based on the load-deformation r e l a t i on
ship of the pla te mater ia l loaded in tens ion ~ i 2 and t h a t
of th e high s t rength bol t s loaded in shear Fig. 3 . A s imi
l a r method was used in Ref. 12 fo r aluminum al loy r ive ted
j o i n t s Since the b ehavior o f th e b ol t in shear i s somewhat
di ffe ren t depending on whether the shear j i g i s loaded in
compression or in tens ion, the theore t i ca l r e s u l t wil l depend
upon which shear curve i s used.
The theore t i ca l curve in Fig . 8 i s based on the be
havior of a b o l t loaded in a tens ion shear j i g t i s seen
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
25/52
288.4 -23-
tha t the a ctu al s tr en gth i s somewhat grea te r than t he p re dic te d
value . This i s to be expected as not l l bo l t s are subjec ted
to the prying act ion experienced by the en d rows. This same
information i s given in Table 6 in comparison with the t e s t
r e su l t s ; along with these , are shown the r e su l t s o bt ai ne d u si ng
the shear deformation re la t ionsh ip given by the compression
t e s t of a s in g le f as te ne r method 1 ) . s expected, the
l t t e r predic ts a higher s t reng th . The resu l t s from a th i rd
method are also shown in Table 6: The b o l ts in the end two
rows a t each end o f the j o i n t were assumed to be represented
by tens ion loading because of th e prying ac t ion , and fo r th e
remaining bol t s the compression shear-deformation re la t ionsh ip
was used. Although t h i s method gives th e most prec i se agree
ment within one percent ) the ref inement may not j u s t i f y th e
added work.
Figure 9 shows th e comparison of these j o in t s of
A440 s t ee l with those of s t e e l Th e average shear s t r e s s
has been taken as the product of the unbuttoning fac to r an d
the minimum tens ion shear s t rength of a s ing le b o l t . The
compression and tens ion shear strengths of s ing le bo l t s a re
also shown in the f igure . For shor t j o in t s the higher s t reng th
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
26/52
288.4 -24-
s t ee l r e su l t s were about the same as A7 the t e s t average being
shown by the so l i d l ine ; but in the long jo in t s the performance
of A325 bol t s was be t t e r in the A440 s t e e l
A par t of the reason for the improved performance
of the A325 bol t when used with higher s t rength s tee l s i s
i l l u s t r a t e d in Fig. 10. Here the computed bol t shear s t r e s s
in each row a t two di ffe ren t stages are shown for j o in t s of
equal length and the same number of A325 fas teners .* The
upper se t jo in t E10l i s for A440 s t e e l the lower se t 0101
i s fo r A7 s t e e l an d the geometry of the j o in t i s shown
between the two graphs.
The f ig u re i nd ic at es t h a t the higher yie ld s t rength
s t e e l effec t s a be t t e r dis t r ibu t ion of the bol t fo rces , the
s t resses being more uniform in j o i n t E10l than in the case of
0101. At f a i l u r e , in 0101 A7 s t ee l the s t resses in the
bol t s near the middle of th e j o in t were l e ss than hal f those
of the end bo l t s . The higher yie ld s t r e s s of the A440 s t e e l
in E10l allowed a be t t e r red is t r ibu t ion because ine las t icdeformations occurred in a l l bol t s while the p la t e mater ia l
* The computations are based on the methods described in Ref. 11.
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
27/52
288.4 -25-
was s t i l l e l a s t i c an d r e l a t i ve ly r i g i d In the lower yie ld
s t r e s s s t e e l i ne l a s t i c deformations occurred f i r s t in
the p l a t e a nd nearly simultaneously in t end f a s t ene r s ,
an d t h i s caused increased deformation in the en d fas teners .
s a r e s u l t the en d bo l t s continued to pick up load a t a fa s t e r
r a t e and did not allow r ed i s t r i bu t i on to occur as well as in
the higher yie ld s t reng th s t e e l s i l l u s t r a t e d in Fig. 10
the i n t e r io r b o l ts in the mild s te el j o in t showed l i t t l e change
in load-carrying a b i l i t y from the onset o f major yie ld ing u n t i l
an end bol t f a i l ed .
These r e su l t s suggest t h a t allowable s t resses to be
used for long A440 j o i n t s might well be higher than t h a t per
m itted for s imi la r s t e e l j o i n t s A more de ta i l ed d i s
cussion concerning the design of bol ted j o i n t s can be found
in Ref. 7.
2. Effect of Jo in t Width
The e ff ec t of in te rna l l a t e r a l forces caused by p l a t e
necking near the ul t ima te t e n s i l e s t reng th of a wide j o i n t was in
ves t iga ted with t e s t s of three j o i n t s E46 E74 an d E74l as
shown in Table 3 .
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
28/52
288.4 -26-
Jo in t E 6 ha d a width th ree t imes as g r e a t as j o i n t
E4l. By comparing the r e su l t s in Table 3 with those in Table 2 ,
the f a i l u r e load of 218 kips fo r E46 i s seen to be exact ly
th ree t imes the ul t ima te load of E4l. Th e j o i n t width had no
effec t on the u lt im a te s tr en g th in t h i s case . Th e t e s t point
i s plo t t ed in F igs . 8 and 9 as an open c i r c l e
Jo in t E74 seven b o l ts in a l i n e with four l i n e s
unbuttoned a t a load of 241 kips . This was s l i gh t l y more than
twice the u lt im a te s tr en g th of j o i n t E7l with seven b o l t s in
l i n e but with only two l ines of fas teners . Again j o i n t width
had no effec t on the ul t ima te s t reng th . After s l i p load
occurred, but p r io r to b o l t f rac tu re , j o i n t E74 f a i l ed pre
maturely in the region near the g r i p s . The above r e s u l t was
obtained f t e r the gripping area was repa i red . In Fig. 8
the t e s t point fo r E74 can be seen as the topmost of the
th ree shown t s ix pi tches .
Jo in t E74l was a dupl ica te of j o i n t E74 This j o i n t
was fabr ica ted and t e s ted because of the f a i l u r e in th e grip
region experienced in j o i n t E74 J o i n t E74l f a i l ed when a
corner bol t unbuttoned a t a load of 225 kips . This load was
about 5 l e s s than tw ice the u lt im a te s tr en g th of j o i n t E7l,
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
29/52
288.4
and the corresponding t e s t po in t i s shown in Fig. 8 as the
lowest of the open c i r c l e s a t s ix p itch es .
-27-
St ra in gages, placed t ra nsve rse to the l i n e of load
on the dead en d of the lap pla tes of j o in t s E46 and E74
ind ica ted compressive s t r a in s between b o l t s . This cons t i tu ted
a d i r e c t indicat ion of the presence of l a t e r a l forces because
of the suspected Poisson s e ff ec t in the wide j o i n t s . Th e
corresponding bol t shear force ac t ing perpendicular to the
j o i n t load was es t imated to be approximately 4 to 12 k s i
However once major yie ld ing occurred in the main p l a t e and
l a rge s he ar d ef or ma ti on developed in th e b o l t s , the t ra ns ve rs e
s t r a in s were reduced u n t i l the t ransverse bo l t shear s t r e s s
was es t imated to be 1 to 5 k s i .
With these r e su l t s i t i s thus concluded t ha t the
e ff ec t of j o i n t width i s not s ign i f i c an t in bu t t j o in t s of
A44 s t e e l p l a t e fas tened with A325 b o l t s . Pla te necking
was found to con t r ibu te to the premature corner bo l t f a i l u r e s
in j o in t s of s t e e l 2 .
3. Effect of Varia t ions in Pla te Area
The p i l o t t e s t s e r i e s fo r the A44 s te el j o in ts allowed
an evaluat ion of the performance of the bo l t s when the t e n s i l e
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
30/52
288.4 -28-
area was var ied. As the p la t e area a t the n et sectio n was
increased from 95 to 110 of the bo l t shear area , the bo l t
shear s t r e s s increased from 78.4 to 81.3 ks i . a s indicated in
Table 1 . This increase i s to be expected as th e larger p la t e
area has a grea te r s t i f f ne s s and al lows a be t t e r r ed i s t r i bu
t i on .
The r e su l t s of t e s t s of A7 s t e e l j o in t s which had
large var ia t ions in the p la t e area were analyzed an d d i s
cussed in Ref. 7. The same type behavior was found fo r both
A7 and A44 s t ee l when the p la t e area was var ied .
When the ne t p la t e area i s decreased r e l a t i ve to the
b o l t shear area the j o in t s invar iably f i l by t ea r ing of the
p la t e such as was the case fo r j o i n t E4 a see Table 1 ) . As
a r e s u l t the re i s no way to determine the shear s t reng th of
the fas teners . For th e compact A44 s t e e l jo in ts th is occurred
when the p la t e area was 90 of the bo l t shear area . This same
phenomenon was observed in compact A7 s t e e l j o in t s t .approxi
mat ely 95 of the bol t shear area 2 ) .
4. Jo in t S l ip
The fac to r which determines the load t j o i n t s l i p i s
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
31/52
288.4 -29-
ca l led the nominal coe ff i c i en t of f r i c t i on or s l ip coe ff i c i en t
Ks This s l i p coe ff i c i en t necessar i ly depends on th e c on ditio n
of the faying surfaces an d the clamping forces induced by the
bo l t s . On the bas i s of a v i sua l in sp ec tio n th e ro lle d m il l -
sca le surface of A44 p la t e mater ia l used in the t e s t j o in t s
was qui te hard and smooth. The bo l t s were t ightened according
to the turn-of-nut method l) an d re su l ted in b o l t clamping
forces which showed no marked var ia t ions from the average bo l t
tens ion.
Bolt elongations were measured during f ab r i c a t i on .
The histograms of the bo l t tens ion d i s t r i bu t i on were s imi la r
to those repor ted in Ref. 2. The average elongations and
t he i r corresponding bo l t tens ion a re given in Tables to 3.
The mean elongation ranges from 0.033 to 0.0463inches fo r
ha l f of a turn an d i s about 0.0556 inches fo r th ree q uar ters
of a tu rn . The corresponding bo l t tens ion i s approximately
1 .3 t imes th e proof load of l i inch A3 5 bo l t s in e i t he r s e ~
The nominal s l i p coe ff i c i en t s obtained fo r each j o i n t are r e -
corded in Tables 2, an d 3. The average s l i p coeff ic ien t
computed for these t e s t s was Ks = 0.32. The s l i p coe ff i c i en t s
were determined from the re la t ionsh ips given in Ref. 2
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
32/52
288.4 -30-
Figure i s a bar graph which i l l u s t r a t e s the s l i p
res i s tance of the A44 s t ee l j o i n t s The hor izon ta l l i ne
extending across the graph a t F v = 5 k s i represen t s the
working s t r e s s l eve l according to th e ISC spec i f i ca t ions fo r
f r i c t i on - type connections 13 . The hor izon ta l l i ne a t
F v = 2 k s i would apply fo r connections subjected to s t a t i c
plus wind loading and in which a one- thi rd increase in allow
able s t r e s s i s permit ted . The height of each bar ind ica tes
the average bo l t shear s tr e s s a t s l i p The r e l a t i ve ly low
s l i p res i s tance of j o in t E4lb has been a t t r i bu t ed to warping
during th e bolt ing-up operat ion.
Th e average s l i p coe ff i c i en t of 0.32 obtained in
these A44 t e s t s i s but s l igh t ly l e ss than the v al ue s o bt ai ne d
in the s imilar s e r i e s 0 .35 2 ,3 . With t h i s r e s u l t
coupled with the fac t t ha t no j o in t s s l ipped below an average
s t r e s s of 2 ks i , i t i s c lea r th at these j o in t s a l so meet the
requirements of the spec i f i ca t ion 14 .
9. SU RY
These conclusions are based on th e r e su l t s of four teen
t e s t s of large bol ted jo in t s of A44 s t e e l connected with A325
high-s t rength bol t s and upon re la ted t h eo re t i c a l ana lys i s .
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
33/52
288.4 -31-
Many of the conclusions are re inforced by the r e su l t s of t e s t s
of j o in t s of A7 s t ee l connected with A325 bo l t s . The jo in t s
were but t - type p la t e sp l ices proport ioned with the area of
the pla te mater ia l t the ne t sec tio n equal to the shear area
of the bo l t s . The e ff ec t of j o i n t length upon the ul t imate
s t reng th of the connection was invest igated an d a few t e s t s
were conducted to determine the e ff ec t of j o i n t width.
1 . Jo in t s of A s t e e l with up to four A325 fas teners
in l i ne were capable of d ev el op in g a bo ut 96 of th e shear
s t rength of a s ing le bo l t Fig. 8 . This r e su l t did not d i f f e r
s ign i f ican t ly from the shear s t reng th of A325 bo l t s in s imi la r
A7 s t e el j o in ts
2. In j o in t s with more than four fas teners in l i n e , the
d i ff e ren t i a l s t r a in s in the connected mater ia l caused the end
bo l t s to shear before l l bo l t s could develop t h e i r f u l l
shearing s t reng th . At seven fas teners in l ine 24 .5 - in .
about 87 of the shear s t reng th of a s ing le bo l t was developed.
T hi s d ec re as ed to about 8 fo r a j o i n t with s ixteen fas teners
in l i ne 52 .5 - in . as shown in Fig. 8. As can be seen in Fig. 9
th i s decrease was not near ly as grea t as was experienced in A7
s te el jo in ts
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
34/52
288 4
3
32
Good agreement was obtained between the t e s t r e su l t s
an d the t h eo re t i c a l ana lys i s When t he t en si on sh ea r deforma-
t io n r el at io n sh ip of th e bol t s was considered th e computed
s t rength was within of the t e s t r es ul t s .
4 n increase in j o i n t width had no appreciable e ff ec t
on the ul t imate s t rength of the j o i n t . Evidently th e l a t e r a l
forces du e to necking in the p la t e mater ia l were not as
ser ious as was the case with e a r l i e r t e s t s of s t e e l j o i n t s 2 .
5 The presence or absence of washers under the bo l t
head an d nut had no appreciable e ff ec t on the behavior of
th e j o i n t . ny di ffe rences between the t e s t j o in t s could be
a tt ri bu te d d ir ec tl y to the var ia t ions in th e bo l t shear
s t reng ths as repor ted in Table 5
6 Controlled v ar ia tio n in the p la t e area a t the ne t
s ec ti on a ff ec te d the bo l t shear s t rength as would be expected
s the p la t e area increased grea te r r i g i d i t y was achieved and
corresponding higher shear s t rength of the bo l t groups r e su l t ed
7 The experimental and ana ly t i c a l r e su l t s suggest t ha t
the allowable s t r e s s to be used in long A s te el jo in ts
might well be higher than t h a t permitted fo r s im ilar s t e e l
j o i n t s .
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
35/52
288 4 33
8 All bol t s were t ightened by the tu rn o f nu t method
and consis tent ly had preloads approximately 1 3 t imes the proof
load of the bo l t
9 These t s t s gave mean coeff ic ien t of s l p for t i gh t
mil l sca le faying su rfaces of Ks 0 32 Nei ther j o n t length
or width had any appreciable e ff ec t on th e s l p coe ff i c i en t
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
36/52
288.4
CKNOWLEDGEMENTS
34
The work described in t h i s paper i s par t of an in -
vest igat ion of large bol ted j o in t s being conducted a t the
Fr i t z Engineering Laboratory Department of Civi l Engineering
Lehigh Univers i ty. Professor William Eney i s head of the
Department. The pro jec t i s sponsored f inancial ly by the
Pennsylvania Department of Highways the Department of Commerce -
Bureau of Public Roads and the American Ins t i t u t e of ~ e e l
Construction. Technical guidance i s provided by the Research
Council on Riveted and Bolted Structural Jo in t s .
The authors wish to acknowledge the guidance an d
advice of the advisory committee under the chairmanship of
Dr. L u m p f ~ Thanks are also due to the Bethlehem Stee l
Company par t icu la r ly W H Jameson K de Vries T. W.Spilman
an d A Schwartz. The c oo pe ra tio n o f S. Errera K R Harpel
and the s t a f f of technicians a t the Fr i t z Engineering Labora-
tory i s gra te fu l ly acknowledged
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
37/52
288.4-
NOMEN L TURE
1 . ymbols The net t ens i l e area of the p la t e
-35-
The bo l t shear area for b u tt -t yp e s p li ce s the re
are two shear planes
Tis Ratio of the t n s i l s t r e s s on th e ne t sec t ion of
p l a t e to the shear s t r e s s on th e nominal area o f
th e fa ste ne rs AsiAn
u The unbuttoning fac to r def ined as th e r t i o of
the average bo l t shear s t r e s s in the connection
when th e f i r s t bo l t shears to th e ul t imate
s t rength of a s ingle bo l t of the same l o t and
of the same gr ip
n The ul t imate t n s i l s t r e s s on the net sec tio n
~ The average bo l t shear s t r e s s in the bo l t ed
connection a t f a i l u r e
The shear s t rength of a s ingle bo l t subjected to
double shear by p l a t e s loaded in compression
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
38/52
288.4
1: t
2. Glossary
Gage
Grip
Pitch
PryingAction
SlipCoeffi-c i en t
Snug
36
The shear s t rength of a s ing le bo l t subjected
to double shear by pla tes loaded in tens ion
The t ransverse spacing of the bo l t s
The th ickness of the p la t e mater ia l in the
connection
The longi tudinal spacing of the bo l t s
The tendency fo r the lap p la t e ends to bend
out due to the b ea ri ng c o nd it io n
Ks
= P s m ~ T iwhere Ps
s the major s l ip load
m the number of s l p planes an d 2.Ti = u of
the n t l bo l t tens ions
The expression used to descr ibe the t ightness
of a bol t before beginning the tu rn of the nut .
Snug s indicated by the impact wrench when
impacting begins .
Unbutton The sequent ia l f a i l u re of fas teners which pro-ing
gresses from the ends of a j o in t inward
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
39/52
TABLE 1: NOMINAL DIMENSIONS ND TEST R E S U L T S ~PILOT TESTS 4 - 7 / ~ A 5 bol ts pe r l ine
1 m n : . . ~ _ 1 _ / 2W_id th - - - - l i 1k--.l Pitch l 3-1/2
ITEM UNITS E41a E4lb E41e 4l f 4l
BOLTS -Regu la r HeadNominal S he ar A re aWashers Used
PLATESMean Width in .Mean Thickness (two plates) in .Mean G ro ss A re a in 2Mean N et A rea in 2
As:A n (T:S)NominalActual
9.622
6.122.01
12.318.54
1:0.901:0.89
9.622
6.422.01
12.879.11
1:0.951:0.95
'9.622
6.592.01
13.259.49
1 ~1.001:0.99
9.622
7.152.02
14.4310.65
1: 1.101:1.11
9.621
6.662.00
13.349.58
1 ~1.001: 1.00
9.62o
6.682.01
13.439,66
1:1.001: 1.0
SLI P LOAD (TEST)'Bolt Shear St re s s 'Avg. Ext. of BoltsClamping F or ce P er BoltSlip Coeff ic ient
TYPE OF FAILURE
LOAD AT FAILURE
Bolt Shear Stress
kipsks iin . tips
kipsksi
6
27'.20.0389
51.1
Pla te
73075.9
19820.6 '
0.039951.2
0'.24
A ll bo1 t ssheared
75478.4
2602 7 ~ 0
0.033350.3
0:'32
All bol tssheared
77080.1
28229;3
0.046351.
0.34
All bol tssheared
78281.3
27028.1
0.036448.3
0.35
All bol tssheared
72775.6
28229.3
0.03951.2
0':34
All bsheare
76779.8
These connections had h ea vy h ea d bo l t s ; in connections t he t hr ea ds were excluded from th e shearp1ane c o
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
40/52
TABLE 2: NOMINAL D I M E N S I O ~ SAND tEST RESULTS: LONG JOINTS
n - 7/8 bo l t s pe r l ine
~ 2 or 4 grip 1 or 2I
ITEM
- Heavy Head,1 Washer
No o in LineNominal S he ar A re a
PL T S
Grip (excluding washer)Mean WidthMean ThicknessMean Gross AreaMean Net Area
As :A
n(T: S)
NominalActual
SLIP LOAD (TEST)Bolt Shear StressAvg. Ext. o f Bol tsClamping Force Pe r no1tSl ip Coeff ic ient
TYPE OF FAILURE
LOAD AT FAILURE
Bol t Shear Stress
UNITS
in .in .in .in 2in 2
kipsksiin .kips
kipsksi
E4 l
49.62
4.046.672.02
130
49
9 < 7
1: 1.001;1.01
25026.0
0.040648.6
O ~ 3 2
All bo l t ssheared
72875.7
E71
716.83
4.0010.28
2.0020.5616.81
1:1 .001: 1.00
40023.8
0.036148.3
0 .30
One bolt .sheared
118870.6
ElOl
1
24.04
4 0 0013.88
2.0027 0 79
24.04
1: 1 .001: 1.00
61425.5
0.045348.9
0.31
One bo l tsheared
161067.0
E13l
13
31.25
7.969 ~
3.9838.5331.06
1: 1.001:0.99.
82426.4
0.055248.1
0.33
One bol tsheared
212568.0
E16l
16
38.46
7.9811.47
3.9945.6738.23
1: 1.001 : ~99
102826.7
0.057048.2
0.33
One bo l tsheared
254566.2
. . . : . J I . ~ . . . . . . . . : : . . . . . : . . . : . . . l _ _ l _
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
41/52
TABLE 3 ~ DIMENSIONS N TEST RESULTS: :WIDE JOINTS
JOINTE46
I I :: : ..;7----=l:A;:::==t=== ===t=:r==----- lI- ~ . . . .
I I I- -H - , - \ - --- - --- - I - _
~ . . j . ./ H L
3.34 1 ~ I v :
3-1/2
l _ : ~ __ t ~= ~ i = = : j = = : j : = i l =~ :..L:_.: _
l ~ i t ~ h=
I :I I
JOINTSE74E741
2grip = 4
I
ITEMT
UNITS E46 E74 E741
BOLTS - Heavy Head, 1 WasherNominal Shear Area . 2 28.85 33.67 33.67
PLATESMean WidthMean ThicknessMean Gross AreaMean Net Area
in .in .in 2in 2
20.042.03
40.6229.22
20.571.99
40.9933.51
20.552.01
41.2233.70
As.:Ap.. {T.: 8NominalActual
1: 1.001:1.01
l ~ 1.00. 1: 1.00
l ~ 1.00bl .OO
SLIP LOAD TESTBolt Shear StressAvg. Ext. of BoltsClamping Force Pe r BoltSl ip Coefficient
. kips. ksi
in .kips
79827.7
0.045648.9
0.34
91227.1
0.040348.6
0.34
68020.2
0.036048.3
0.25
225066.9
One bolsheared
One bol tsheared
*41071.6
218076.5
All bol tssheared
kipsksi
TYPE OF FAILURE
LOAD AT FAILUREBolt Shear Stress l ----L- . l . . .
* Earl ier f rac ture of the plate occurred a t a load of 2240 kips
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
42/52
TABLE 4: PROPERTIES OF PLATE
es t Number Sta t i c Yield St re s s ksi Yield Stress . ksi Ult. Ten. St r. , ksi Elong. ReductionSer ies of in 8 i n area
Coupons Mean Std. Dev. Mean Std. Dev. Mean Std. Dev. inches
Pi lo t 10 43.0 1.17 45.3 1.15 75 0 4 1.71 28 0 9 64.5
All Others 30 42.9 0.73 45 0 3 0.70 76.0 1.01 27 0 7 61. 7
Combined 40 42.9 0.84 45.3 0.82 75.8 1.22 28.0 62.4
Taken t a 0.2 s t r i n
TABLE 5: PROPERTIES OF 7/8- in . BOLTS
Compression Ten s io n S h ea rLength Direc t Tensile Torqued Tensi le Shear Strength Strength
Used in Bolt Under Thread Strength kips Strength kips C c . ksi t t ksiLengthJoints Lo t Head, inchesinches No Mean Std. No. Mean Std. Noo Mean Std. No Mean Std.
Dev. Dev. Dev. Dev.
E4la b D 5. 5 2 5 56.9 0.55 4 51.1 0.77 3 88.9 1.14 3 84 0 4 1.95c e
E4lg 8A 5.25 1. 5 5 59.4/ /1.11 5 52.2 1.91 3 85.1 2.00 3 82.0 0 0 54
E4lf 8B 5.5 1.5 5 55.5 1.12 5 49.3 1. 68 3 86.1 1.46 3 76 0 9 78E4l-ElOl
El3l H 9. 5 1. 75 7 58.3 1.28 6 48.3 1.69 3 86.0 2.04 3 79.2 0.46E16l
There were no threads i n t he s he ar in g planes
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
43/52
TABLE 6: COMPARISON OF TEST RESULTS N
COMPUTED STRENGTH
COMPUTED ULTIMATE STRENGTH KIPS
JOINT LOAD ATMethod 1 Method 2 Method 3 FAILURECompression J ig Tension J ig Combined KIPS
E41 8 6 729 728E4lf 8 6 729 727E41g 8 776 767E7 l 1282 1178 12 1188
E1 1 1696 1588 1612 161
E131 2163 2 62 21 2 2125
E161 2599 2496 2538 2545
The bol t s in th e end two rows a t each end of th e j o in t were assumed to be
represented by th e tension shear-deformation re la t ionship . The remaining
bol t s by th e compression shear-deformation re la t ionship .
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
44/52
80
60
20
//
//
//
/0.00 /
Yield SIress Level 0.2 .
0.010
0.05 1 15
STRAIN,IN/IN
0.20 0.25
FIG TYPIC L STRESS STR IN DI GR M FOR PL TE M TERI L
E7I,g=5.14
E o,b,lI 3.32
40 0
100
D r i l l e d l ~
3p
o 1 0.2 0 .3 0 .4 0.5ELONGATION IN 3.5 PITCH inches)
FIG 2 RESULTS PL TE C LIBR TION TEST
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
45/52
Compression Shear90
iii 8 \ ll \ ri
\ 7\
t ::
:: 6Tension Sheorl:
w x
II I 4w )
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
46/52
70
60 V /lIui Bolt failure sequenceel 50 X tii
40:I: /
5 30
UJ )
Ii 20UJ
XEIOI
1
1 0.20 0.30 0.40 0.50 0.60 0.70 0.80
FIG 5
DEFORMATION X-X INCHES
TYPIC L LO D DEFORM TION CURVE
FIG 6 S WE SECTION OF JOINT E7 l
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
47/52
FIG 7 JOINT E1 l SHOWING SHEARED BOLT SHANKSAFTER UNBUTTONING
NUMBER OF PITCHES AT 3 5 INCHES6 9 12 151 0 = = : = : ~ i : r T T T
Ito 8~< >
CzZ 6g~::::llDZ ~ 4~
2
~ E
P _ E741 / 7 ~
Single FastenerComputed
o 1 2 3
JOINT LENGTH INCHES
4 5
FIG 8 EFFECT OF JOINT LENGTH THE UNBUTTONING FACTOR
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
48/52
Test Average A7
F =22 kSi(l3) , ~
co:preSSion Shear Strength,Single Bolt
~ Tension Shear Strength,Single Bolt ____ Theoreticol,A440
i - -~
o ~ ~60
20
1
o 1 30 40 5
JOINT LENGTH INCHES
FIG 9 COMPARISON OF A44 STEEL BUTT JOINTS NDA7 STEEL BUTT JOINTS
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
49/52
Bolt Stress at Ultimate
ProportionalLimit ofBolt
JOINT E A44 STEEL
8
6
5wa:
a: t
3Cf
2
ProportionalLimit ofBolt
JOINT A7 STEEL
Bol t Stress at Onset ofMajor i e l i n ~In GrossSection of Plate
I I I I I I I I FI 2 3 4 5 6 7 8 9 10
Bolt Stress at Ultimate
8
2
FIG 10 LO P RTITIO N IN BOLTED JOINTS
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
50/52
E410
E41b
E41c
E41e
E41f
E41g
E41
E71 .
EIOI
EI31
EI61
t:
E46
E74
E741
FIG 11
AVERAGE BOLT SHEAR STRESS, ksi)
o I
iI I
1 2 7 2
20.6 0
(2'7.0 29.3
en n128 1
129.3
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
51/52
288 4
REFERENCES
1 Research Council on Riveted and Bolted Struc tura lJoints of the Engineer ing Foundation
SPECIFICATION FOR STRUCTURAL JOINTS USINGASTM A325 BOLTS 1960
2 Foreman, R. T Rumpf, J L.STATIC TENSION TESTS OF COMPACT BOLTED JOINTSTransactions ASCE, Vol 126 Part I I 1961
Summarized by Bruno Thur1imann RESEARCH ONLARGE COMP CT JOINTS WITH HIGH STRENGTH STEEL O L T S ~IABSE, Final Report of the SixthCongress in Stockholm 1961
3 Bendigo R. A Hansen, R. M., Rumpf, J LLONG BOLTED JOINTSFr i t z Laboratory Report 271 18 LehighUniversi ty 1962
4 Wy1y, L. T Treaner H. E LeRoy, H. E.DEMONSTRATION TEST OF N A242 HIGH STRENGTHSTEEL SPECIMEN CONNECTED Y A325 ND A354BDBOLTSAISC Proceedings 1957
5 Hansen, N. G.FATIGUE TESTS OF JOINTS OF HIGH STRENGTH STEELSTransactions ASCE, Vol 126 Part I I 1961
6 Davis R. E Woodruff G. B Davis H. E. TENSION TESTS OF LARGE RIVETED JOINTS
Transactions ASCE, Vol 105 P 1193 1940
7 Fisher J W., Beedle L SCRITERIA FOR DESIGNING BOLTED JOINTS BEARING-TYPE)Fr i t z Laboratory Report 288 7 Lehigh Univers i ty
1963
8 American Standards AssociationSPECIFICATIONS FOR SQUARE ND HEX GON BOLTS ND NUTSB 18 2 1960
-
8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat
52/52
288 4
9 Fisher R. ASTATISTICAL METHODS FOR RESEARCH WORKERS
Oliver and Boyd, Edinburgh10 Rumpf, J L Fisher J W
CALIBRATION OF A325 BOLTSFr i t z Laboratory Report 288 5 Lehigh Univer-s t y 1962
11 Rumpf, J L.THE ULTIMATE STRENGTH OF BOLTED CONNECTIONSPh.D Disser ta t ion Lehigh Univers i ty 1960
12 Francis A JTHE BEHAVIOR OF ALUMINIUM ALLOY RIVETED JOINTSThe Aluminium Development Association ResearchReport 15 London, 1953
13 American In s t i t u t e of Steel ConstructionSPECIFICATION FOR THE DESIGN FABRICATION NDERECTION OF STRUCTURAL STEEL FOR BUILDINGS 1961
14 Resea rch Counc il on Riveted and Bolted St ruc tura lJo in t s of the Engineering Foundation
SPECIFICATION FOR STRUCTURAL JOINTS USINGASTM A325 BOLTS 1962Proceeding of ASCE Vol 88 ST5, 1962