strength of a440 steel joints connected with a325 bolts publicat

8/14/2019 Strength of a440 Steel Joints Connected With a325 Bolts Publicat

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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 .


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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.


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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 ,


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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


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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


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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


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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)


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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


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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


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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


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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


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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


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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.


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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


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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


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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


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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


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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


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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


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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


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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


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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.


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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


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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


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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.


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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 .


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,


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


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


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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


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 .


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


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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 .


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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


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


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


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


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


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 _


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


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


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 .


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


45/52

Compression Shear90

iii 8 \ ll \ ri

\ 7\

t ::

:: 6Tension Sheorl:

w x

II I 4w )


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


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


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


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


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


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


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

strength of a440 steel joints connected with a325 bolts publicat

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