ILL IN 0 I S - CORE · characteristics of the 7 s-in. hand-pneumatic driven rivets is given in Fig....

ILL IN 0 I SUNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN

PRODUCTION NOTE

University of Illinois atUrbana-Champaign Library

Large-scale Digitization Project, 2007.

The Static Strength of Rivets Subjected

to Combined Tension and Shear

William H. Munse

Hugh L. Cox

^!W.

sali-sMt^

AN INVESTIGATION

ZING EXPERIMENT STATION)F ILLINOIS

i with

4 COUNCIL ON RIVETED AND BOLTED STRUCTURAL JOINTS

DIVISION OF HIGHWAYS

The Static Strength of Rivets Subjected

to Combined Tension and Shear

by

William H. Munse

RESEARCH PROFESSOR OF CIVIL ENGINEERING

Hugh L. Cox

FORMERLY RESEARCH ASSISTANT IN CIVIL ENGINEERING

ENGINEERING EXPERIMENT STATION BULLETIN NO. 437

4550-12-56-59699

CONTENTS

I. INTRODUCTION 7

1. Object and Scope of Investigation 72. Acknowledgments 7

II. DESCRIPTION OF TEST SPECIMENS AND EQUIPMENT 8

3. Description of Test Specimens 8

4. Description of Equipment 105. Details of Test Programs 12

III. PRELIMINARY TESTS 13

6. Effect of Rivet Material 13

7. Effect of Driving Time, Soaking Time, andFurnace Temperature 14

8. Variation in Ultimate Strength With Shear-Tension Ratio 15

IV. RESULTS AND ANALYSIS OF SHEAR-TENSION TESTS 19

9. Results of Tests 19

10. Effect of Shear-Tension Ratio 21

11. Effect of Grip 24

12. Effect of Rivet Diameter 25

13. Effect of Rivet Manufacture and Fabrication 25

14. Discussion of Possible Design Rules 26

V. SUMMARY OF RESULTS AND CONCLUSIONS 28

15. Summary of Results 28

16. Conclusions 28

FIGURES

1. Details of Test Specimen 82. Sections of 1-in. Grip Hot-Formed Rivets. Hand-Pneumatic Driven 8

3. Sections of 7%-in. Diameter Hot-Formed Rivets. Hand-Pneumatic Driven 8

4. Sections of 2-in. Grip Rivets. Hand-Pneumatic Driven 95. Sections of 5-in. Grip Hot-Formed Rivets 96. Hand-Pneumatic Driving of Rivets 10

7. Cut-Away View Showing Method of Gripping Test Specimens 108. Assembly of Test Fixture for Direct Tension Test of Rivets 11

9. Cut-Away View Showing Method of Measuring Rivet Elongationand Lateral Slip 12

10. Stress-Strain Curves for Preliminary Specimens Tested inDirect Tension 14

1 1. The Effect of Driving Time, Soaking Time and Temperature onthe Ultimate Strength of Rimmed Steel Rivets 14

12. Interaction Curves for Preliminary Tests at Various Shear-Tension Ratios 16

13. Fractures of Specimens Tested at Various Shear-Tension Ratios 16

14. Interaction Curve for Preliminary Specimens Tested at VariousShear-Tension Ratios, Based on Coupon Strength 17

15. Effect of Shear-Tension Ratio on Ultimate Strength of Rivets 17

16. Deformation Measured Normal to Rivet Axis for Preliminary Tests 17

17. Axial Elongation for Rivets of Preliminary Tests 18

18. Typical Fractures at the Four Shear-Tension Ratios 21

19. Typical Load-Deformation Curves for Rivets Tested at VariousShear-Tension Ratios 21

20. Interaction Curve for Rivets of all Series of Primary Test Program 23

21. Relation of Interaction Coefficient to Tension-Shear Ratio 24

FIGURES (Concluded)

22. The Effect of Rivet Grip on Ultimate Strength at Four DifferentShear-Tension Ratios 25

23. Effect of Rivet Diameter on Ultimate Strength at Four DifferentShear-Tension Ratios 26

24. The Effect of Method of Rivet Manufacture and Fabrication onUltimate Strength at Four Different Shear-Tension Ratios 27

25. Comparison of Various Relationships for Allowable Unit Stresses 27

TABLES

1. Chemical Composition of Rivet Steels 92. Mechanical Properties of Rivet Material Before Driving 103. Results of Tests of 7a-in. Rimmed, Killed, and Semi-Killed Rivets 134. The Effect of Driving Time, Soaking Time, and Temperature on the

Ultimate Strength of Rimmed Steel Rivets 145. Results of Preliminary Tests at Various Shear-Tension Ratios 156. Outline of Test Program 197. Summary of Test Results of Series 1 198. Summary of Test Results of Series 2 199. Summary of Test Results of Series 3 20

10. Summary of Test Results of Series 4 2011. Summary of Test Results of Series 5 2012. Summary of Test Results of Series 6 2013. Summary of Test Results of Series 9 2114. Summary of Test Results of Series 10 2115. Average Interaction Data for All Series of Tests 2216. Comparison of Interaction Data with Ellipse 2217. Working Shear-Tension Stresses for Rivets 27

I. INTRODUCTION

1. Object and Scope of Investigation

Present design specifications do not provide forthe use of rivets subjected to combined shear andtension; they only provide for rivets stressed eitherin shear or in tension alone. The Current AISCSpecification for the Design, Fabrication, and Erec-tion of Structural Steel for Buildings permits a de-sign stress of 15,000 psi for rivets in shear and20,000 psi for rivets in tension; the AREA Specifi-cation for Steel Railway Bridges permits a designstress of 13,500 psi for power-driven rivets in shearbut does not refer to the use of rivets in tension;while the AASHO Specification for HighwayBridges allows a design stress of 13,500 psi forstructural carbon steel rivets in shear and alsostates that, "Rivets in direct tension shall, in gen-eral, not be used, but if so used their value shallbe one-half that permitted for rivets in shear."Nevertheless, the rivets in structural connectionsare often subjected to loads which produce a com-bination of shear and tension.

Many tests have been conducted in which rivetswere subjected to shear and tension alone; how-ever, few tests have been made in which the rivetshave been subjected to known combinations ofshear and tension. Wilson and Oliver,* in one ofthe studies which has been conducted on rivets intension, determined the strength of rivets whichhad been subjected to various heating and drivingconditions. Young and Dunbart made tests ofrivets in tension, rivets loaded with a tensile forceequal to the shearing force, and rivets loaded witha tensile force equal to twice the shearing force.In this latter investigation it was found that therivets loaded with a tensile force equal to twicethe shearing force had ultimate strengths about4 per cent less than the ultimate strength of therivets loaded in direct tension, and that the rivetsloaded with a tensile force equal to the shearingforce had ultimate strengths about 35 per cent lessthan the ultimate strength of the rivets loaded indirect tension.

In view of the meager amount of data availableon the strength of rivets loaded in combined shearand tension, the extensive program of tests re-ported herein was planned by the Research Council

* "Tension Tests of Rivets," by Wilbur M. Wilson and William A.Oliver. Bulletin No. 210, University of Illinois Engineering ExperimentStation, 1930.

t "Permissible Stresses on Rivets in Tension," by C. R. Youngand W. B. Dunbar. Bulletin No. 8, University of Toronto Faculty ofApplied Science and Engineering, 1928.

on Riveted and Bolted Structural Joints to studythe question. The primary object of the investiga-tion was to determine more completely the strengthand behavior characteristics of rivets subjected tovarious combinations of shear and tension.

Studies have been made, also, of the manner inwhich the yield strength, ultimate strength, andthe deformations of the rivets were affected bysuch variables as rivet grip, rivet diameter, methodof driving, and type of manufacture of the rivet.In general, the ultimate strength of the rivets hasbeen taken as the basis for comparison. The termshear-tension ratio as used throughout the reportrefers to the ratio of the component of force normalto the rivet axis (shear) to the component of forceacting along the rivet axis (tension).

2. Acknowledgments

The tests described in this bulletin constitute apart of an investigation resulting from a cooper-ative agreement between the Engineering Experi-ment Station of the University of Illinois, theResearch Council on Riveted and Bolted StructuralJoints, the Illinois Division of Highways and theDepartment of Commerce, Bureau of Public Roads.The tests, a part of the Structural Research pro-gram of the Department of Civil Engineering, un-der the general supervision of N. M. Newmark,Research Professor of Structural Engineering, weremade by H. L. Cox, formerly Research Assistantin the Department of Civil Engineering.

The work of this program was planned by theProject III Committee of the Research Council onRiveted and Bolted Structural Joints. This com-mittee was concerned primarily with a study ofthe strength of rivets under combined shear andtension. The members of the Project III Commit-tee were as follows:

T. R. Higgins, Chairman C. H. SandbergFrank Baron W. M. WilsonJonathan Jones W. H. Munse

W. R. Penman of the Bethlehem Steel Companyprovided the rivets that were used in the test pro-gram, and R. S. Wood of the Mississippi ValleyStructural Steel Company arranged for the shopfabrication of the machine driven rivets of the testprogram. The remainder of the rivets were drivenin the Structural Research Laboratory at the Uni-versity of Illinois by the laboratory mechanics ofthe Civil Engineering Department.

II. DESCRIPTION OF TEST SPECIMENS AND EQUIPMENT

3. Description of Test Specimens

The test specimens consisted of high button-head rivets which were driven into pairs of roundblocks of the type shown in Fig. 1. These blockscontained a drilled rivet hole 1/16 in. larger thanthe nominal rivet diameter, and were machinedon all surfaces. The blocks had the same outsidediameter for all rivet sizes. The 1/4 by 1/4 in.undercut at the center of the blocks providedshoulders on which the load was applied to theriveted specimens.

In order to study the hole-filling qualities ofthe rivets driven under the various conditions,longitudinal sections were cut through the centerof a number of specimens. These sections were thenpolished to remove the burrs from the edges of therivets and blocks, and photographed as shown inFigs. 2 through 5. It is evident, in these figures,

dm2

Fig. 7. Details of Test Specimen

Fig. 2. Sections of 1-in. Grip Hot-Formed Rivets.Hand-Pneumatic Driven

that some of the rivets filled the rivet holes betterthan others, but in all cases there was some clear-ance around the rivets.

A demonstration of the effect of a variation ingrip, from 1 in. to 5 in., upon the hole fillingcharacteristics of the 7 s-in. hand-pneumatic drivenrivets is given in Fig. 3. In this case, the rivetswith a 5-in. grip did not fill the hole throughouttheir entire length as well as the rivets with theshorter 1-in. or 2-in. grip. Near the driven head,however, the hole was well filled for all three grips.

Two types of rivet stock were used in thesetests: hot- and cold-formed. Sections of hot- andcold-formed rivets of 2-in. grip which were hand-pneumatic driven are shown in Fig. 4. In these

Fig. 3. Sections of 7/e-in. Diameter Hot-Formed Rivets.

Hand-Pneumatic Driven

Bul. 437. STATIC STRENGTH OF RIVETS IN COMBINED TENSION AND SHEAR

The chemical composition of the rivet steel forthe principal or main series of tests is given inTable 1 and denoted as ASTM A-141. Those speci-fied as rimmed, killed, and semi-killed are therivet steels that were used in a preliminary seriesof tests. Table 2 presents the mechanical propertiesof the A-141 rivet steels as reported in the MillReport, and the properties obtained from standard0.505-in. diam tensile coupons tested in the labora-tory. The ultimate strength determined from testsof the standard 0.505-in. diam specimens wasslightly higher, in most cases, than that reportedby the Mill. However, the Mill Reports gave valuesfor tests that were made on the as-rolled bars,whereas the laboratory tests provide the propertiesof the formed rivets.

Fig. 4. Sections of 2-in. Grip Rivets, Hand Pneumatic Driven,Top, Hot-Formed, Bottom, Cold-Driven

sections there appears to be no appreciable differ-ence in the hole filling quality between the hot-and cold-formed rivets, both hot driven.

Another variable included in this study of thedegree to which the rivets filled the holes was themethod of driving, hand-pneumatic and machine.Figure 5 shows sections of hot-formed rivets of5-in. grip that were hand-pneumatic and machinedriven. Along the length of these rivets there ap-peared to be little difference in the magnitude ofthe clearance between the rivet and the rivetblocks, although the clearance seemed to be some-what more uniform for the machine driven rivetsthan for the hand-pneumatic driven rivets.

In Fig. 5(a) the driven ends (hand-pneumaticdriven) of the rivets are at the top and the buckedends are at the bottom. It can be seen that, nearthe bucked ends, the rivets did not fill the holes aswell as at other points along their lengths. Thiseffect is less pronounced in the machine drivenrivets of Fig. 5 (b) but is still evident. It is believedthat, in general, the hole filling of all of the speci-mens in Figs. 2 to 5 are typical of what might beexpected from ordinary driving procedures.

Table 1Chemical Composition of Rivet Steels

(from Mill Reports)

Types of Steel Chemical Composition in Per Centc Mn P S

Rimmed* 0.25 0.33 0.020 0.041Killed* 0.19 0.49 0.015 0.027Semi-Killed* 0.20 0.53 0.016 0.031ASTM A-141 0.18 0.45 0.011 0.038 Fin 3 .~,-finn~ cf 5-in~ (rin Hnf-Fnrn,~A Riv~fa. Tao.

* These three rivet materials were used in the preliminary tests. Hand-Pneumatic Driven, Bottom, Machine Driven

ILLINOIS ENGINEERING EXPERIMENT STATION

Table 2Mechanical Properties of Rivet Material Before Driving

TypeRivet*

RivetDiam.(in.)

Y4V4

78Y8

Y4Y4

Y8

I1

YieldPoint,

psi40,10043,20041,65042,400

42,40041,55039,65040,60044,20045,10044,65050,50050,45050,47545,90046,20046,050

Properties (0.505-in. Coupon)U(t., Per Cent Per Centpsi Elong. Red.

Area58,300 46.0 65.058,300 47.5 65.958,300 46.7 65.557,300 39.0 67.857,800 38.0 67.257,550 38.5 67.556,300 42.3 66.055,350 43.0 69.055,825 42.7 67.555,300 38.2 68.055,650 38.2 67.0

55,425 38.2 67.558,350 37.0 65.758,650 38.0 66.458,500 37.5 66.156,450 41.7 67.156,450 41.0 68.556,450 41.4 67.8

Hlot-FormedHlot-Formed

AveragelHot-FormedHlot-Formed

AverageI lot-FormedHot-Forined

AverageCold-FormedCold-Formed

AverageCold-ForimedCold-Formed

AverageCold-FormedCold-Formed

Average

HIot-FormedlHot-Formed

Average

* The cold formed rivets were annealed at 1200 F for 15 min after forming.t Mechanical properties were determined before rivets were formed.

The lower portion of Table 2 gives the me-chanical properties of the rimmed steel rivet ma-terial used in the preliminary tests. The propertiesof the semi-killed and killed steel rivets were notavailable for the tests.

4. Description of Equipment

All of the hand-pneumatic driven rivets weredriven in the shop of the University's StructuralLaboratory in accordance with the AISC Specifi-cation for the "Design, Fabrication and Erectionof Structural Steel for Buildings." The rivets wereheated in an electric furnace and then transferredto the driving block shown in Fig. 6. This drivingblock was designed to accommodate the specimensfor all of the rivet diameters and grips. The rivets

Properties (Mill Report)tUlf. Per Centpsi Elong.

8 in.

Per CentRed.A rea

40,100 55,700 29.0 61.3

41,100 55,100 33.5 59.9

37,000 53,900 33.5 59.9

40,100 55,700 29.0 61.3

41,100 55,100 33.5 59.9

37,000 53,900 33.5 59.9

erial

38,630 59,340 31.1 56.7

were driven with a standard 90-lb plneumatic hanm-mer operated at an air pressure of 88 psi.

The machine driven rivets were driven in atypical structural fabricating shop using a hy-draulic press riveter. An oil furnace equipped withstandard blowers was used to heat, the rivets. Thetemperature of this furnace was over 2000 F. Thelength of time the rivets remained in the furnace

Fig. 7. Cut-Away View Showing Method of Gripping Test Specimens

Mechanical Properties of Rivet Rimmed Steel Rivet Mat,(Rivets Used in Preliminary Tests)

42,050 63,300 38.2 61.242,000 63,200 37.8 62.442,025 63,250 38.0 61.8

Fig. 6. Hand-Pneumatic Driving of Rivets


was about 4 min, after which the rivets becamea reddish-white color. Care was taken to insurethat the entire heating and driving process wasperformed by the shop's standard method.

A cut-away view of the test jig that was usedto transmit load to the rivets is shown in Fig. 7.The split loading blocks shown in the photographwere fitted with high strength steel inserts whichgripped the test specimens. The loading blocks, inturn, were attached to pull-plates by means ofassembly bolts. These bolts tied the two halves ofthe split loading blocks and the entire assemblytogether, thereby making it possible to test theindividual rivets.

A diagram of the test fixture oriented for directtension tests is presented in Fig. 8. To assemble thefixture for testing, the four split loading blocks are

placed around the test specimen and the sideplates and split blocks are bolted together with theeight assembly bolts shown. By loading throughany one pair of the holes marked G to A, sevencombinations of shear and tension can be obtainedwhich vary from direct tension to direct shear. Inorder to eliminate bending in the rivets, the loadwas applied to the pull-plates through sphericalseats which were located in the heads of a uni-versal testing machine.

In the preliminary tests, measurements weremade to obtain a general indication of the axialelongation and slip or deformation normal to therivet axis when the rivets were stressed at thevarious shear-tension ratios. The gages which wereused to measure the deformation of the rivets areshown in Fig. 9. The vertical dials to the left and

To grips

Riveted test specimen- (See Fig. /)

0C

Pull plates

Fig. 8. Assembly of Test Fixture for Direct Tension Test of Rivets


Fig. 9. Cut-Away View Showing Method of MeasuringRivet Elongation and Lateral Slip

right of the photograph (dials A and B) measuredthe separation of the two loading blocks. Thisseparation, however, included the elongation of therivet and, in addition, the elastic deformationwithin the loading blocks and the small roundblocks into which the rivet had been driven. There-fore, the vertical dials mounted in line with therivet (dials C and D) were used to obtain thecorrection necessary to determine the actual axialelongation of the rivet.

The two horizontal dials (dials E and F) shownin the lower part of Fig. 9 were used to measure

the slip or movement of the loading blocks in adirection normal to the rivet axis. In addition,measurements were made of the separation of thetesting machine pull-heads as load was applied tothe specimens in order to provide an indication ofthe deformation in the direction of loading.

5. Details of Test Programs

Before proceeding with the main test program,it was considered desirable to make a number ofpreliminary tests to determine the significance ofseveral variables upon the strength and behaviorof rivets subjected to various shear and tensileforces. These initial studies were designed to de-termine which of the driving and testing conditionsrequired careful control and, to some extent, whichvariables needed to be studied further.

Most rivets used in ordinary structural workare made from either rimmed, killed, or semi-killed steels. Consequently, one phase of the pre-liminary testing was developed to determine thedifference in strength between structural graderivets made from these three types of steels.

A second phase of the preliminary study wasdesigned to obtain the ultimate strength and load-elongation characteristics of rivets subjected toloadings at many different shear-tension ratios;the scheduled test program included loadings atonly four different shear-tension ratios. This largervariety of shear-tension ratios made it possible tostudy in greater detail the manner in which therivet properties varied with the shear-tension ratio.

The effects of such variables as driving time,soaking time, and furnace temperature on the ulti-mate strength of hand-pneumatic driven rivetswere considered also in the preliminary tests. Ingeneral the variation in variables was limited to arange ordinarily used in standard shop practice;however, in a few cases, wider ranges of variationwere included. It was hoped that the results of thepreliminary tests involving these variables com-bined with the information available on standardshop practice would permit a better selection ofthe driving conditions for the hand-pneumaticdriven rivets of the test program.

I ,

III. PRELIMINARY TESTS

6. Effect of Rivet Material

The preliminary tests were conducted on 7/ in.rimmed, semi-killed, and killed steel rivets with a2-in. grip. Most of the rivets were heated to 1950 Fin an electric furnace and then hand-pneumaticdriven for 30 see. Some of these rivets were soakedan unusually long time as a result of a delay thatwas encountered in obtaining the desired airpressure for driving; this procedure will accountfor some variation in the results of the tests.

A total of sixteen rivets of the various steelswere tested, the results of which are given in Table3. Specimens 1 to 11 were made of rimmed steel,12, 13 and 25 of semi-killed steel, and 15 to 19 ofkilled steel. Five of the rimmed steel rivets weretested in direct tension and five were tested at ashear-tension ratio of 1.0:0.414. The semi-killedand killed steel rivets were tested only in direct

tension for comparison with the results of thedirect tension tests of the rimmed steel rivets.

The second column of Table 3 gives the soakingtime in the furnace, in minutes, for each specimen.In any analysis of the data, this variation in soak-ing time must be taken into account because of itsinfluence on the strength of the rivets. A grain

growth in the rivet steel will result from an in-crease in the soaking time and cause a reductionin the strength of the rivets. All of the killed steelrivets had approximately the same soaking timeand, as a result, almost identical strengths. Speci-mens 1, 25 and 19, of rimmed, semi-killed andkilled steels respectively, had soaking times whichwere approximately the same. A comparison ofultimate strengths of these specimens, based onthe area of the rivet holes, shows values of 70,200psi for specimen 1 (rimmed), 67,100 psi for speci-men 25 (semi-killed), and 69,000 psi for specimen19 (killed). A similar comparison of yield strengthsprovides values of 37,600 psi, 37,600 psi, and44,900 psi, respectively. Thus, killed steel rivetshad a higher yield strength than the rimmed steelrivets, but the ultimate strengths of the two rivettypes were about the same. The ultimate strengthof the semi-killed rivets was only slightly lessthan that of the rimmed and killed steel rivets.This fact may be attributed to the somewhatgreater soaking time of the semi-killed steel rivets.Nevertheless, the differences were not appreciable.

In the lower portion of Table 3 the results ofthe tests conducted at a shear-tension ratio of1.0:0.414 are presented. The stresses reported for

Spec. Soaking Time Shear-Ten,Number inin Ratio

151918

Average121325

Average1579

11Average

234810

Average

1.0:0.41.0: 0.41.0:0.41.0:0.41.0:0.4

Table 3

Results of Tests of %-'in. Rimmed, Killed and Semi-Killed Rivets

(Hand-Pneumatic Driven, 2-in. Grip)

sion Type of Yield Stress,Steel psi, Based on*

Nominal Area ofRivet RivetArea Hole

Killed ......Killed 51,600 44,900Killed 51,300 44,600

51,450 44,750

Semi-Killed 41,900 36,500Semi-Killed 42,000 36,600Semi-Killed 43,300 37,600

42,400 36,900

Rimmed 43,200 37,600Rimmed 48,300 42,000Rimmed 48,600 42,300Rimmed 46,900 40,850Rimmed 43,300 37,660

46,060 40,080

14 Rimmed 34,900 30,40014 Rimmed 29,800 25,96014 Rimmed 30,000 26,13014 Rimmed 30,000 26,13014 Rimmed 31,700 27,610

31,280 27,240

Ultimate Stress,psi. Based on*

Nominal Area ofRivet RivetArea Hole

80,900 70,30079,400 69,00080,800 70,200

80,360 69,830

71,300 62,00072,500 63,10077,100 67,10073,600 64,06080,700 70,20079,490 69,23076,900 66,98073,340 63,88074,170 64,60076,920 66,98059,900 52,17056,700 49,38055,300 48,17054,200 47,20854,300 47,290

56,080 48,840

* Yield and Ultimate Stresses were obtained by dividing the testing machine load by the nominal area of the rivet and the area of the rivet hole.


these tests were obtained by dividing the totalmachine load (the resultant of the shear and ten-sile components) by the area of the rivet based onthe nominal rivet diameter and the rivet holediameter. The strength obtained at this shear-tension ratio was approximately 73 per cent asgreat as that obtained in the direct tension tests.

Load-elongation measurements were made inthe direct tension tests of the rimmed steel rivetslisted in Table 3 to determine the approximate ini-tial tension that existed in the rivets and thecharacteristics of their stress-strain curves. Theresults of the measurements from the tests ofspecimens 1, 5 and 11 (see Fig. 10) indicated thatthe initial tension in the rivets was approximatelyequal to the yield strength of the rivets. In sometests, however, it was difficult to determine theexact point at which yielding began, particularlyin those conducted under shear or combined shearand tension.

7. Effect of Driving Time, Soaking Time, andFurnace Temperature

The tests to study the effect of driving condi-tions on the strength of the rivets were made on7/s-in. rimmed steel rivets with a 2-in. grip. Thefurnace temperatures were 1800, 1875, and 1950 F,and the driving times ranged from 14 to 30 sec.

60

- 9 0 6

Strain in 000/1 inch per inch

Fig. 10. Stress-Strain Curves for PreliminarySpecimens Tested in Direct Tension

The Effect of Drivingon the Ultimate

Spec. Furnace Temp.No. deg F3p 18004p 18005p 18006p 180071) 18008p 1800

lOp 187511p 187512p 187513p 187514p 187515p 187516p 1875

1 19505 19507 19509 1950

11 1950

Table 4Time, Soaking Time, and TemperatureStrength of Rimmed Steel Rivets

Soaking Timemin281414212823142128142128758

109121132143

Driving Timesee18.518.5*23232318.5

14*1414141423233030303030

Ultimate Loadlb

53,09054,00055,10053,15053,15053,10053,15053,75050,90051,35050,70049,40052,08048,56047,79046,24044,10044,590

* Minimum Driving Time to form a full head.NOTE: All Specimens: 7-in. diam, 2-in. grip, Air Pressure at Driving=

88 psi; tested at shear-tension ratio of 0:1.0.

For each furnace temperature and soaking time,the minimum driving time was selected as the timeto form a full head on the rivet. These minimumdriving times were 18.5 sec for a rivet soaked 14min at 1800 F and 14 sec for a rivet soaked 14 minat 1875 F.

Table 4 presents the results of the drivingstudy tests; Specimens 1, 5, 7, 9, and 11 of theprevious study have been included to give a

56

48-

n 1875 Fo /950 F

44 - - 23 Sec

--- 30 Sec (A)

40 _________0 25 50 75 /00 /25 /50

Soaking time, minutes

561-.1-J [

* m: .

52 - 1800 F4___ /875 F

4 --- 14.0 Sec(8) -- /18.5 Sec

- 230 Sec

0 8 16 24 32 40 46Soaking time, minutes

Fig. 11. The Effect of Driving Time, Soaking Time and Temperatureon the Ultimate Strength of Rimmed Steel Rivets

( % /n rivets2 in. gripRimmed steel

3 --

o Specimen /a Specimen 5A Specimen II

n\-1-_I 1____- - - I----- IL/ C,


broader range of the variables. Although the num-ber of tests was limited, Fig. 11(a) shows thatthere was a definite decrease in ultimate strengthas the soaking time was increased from 7 min to25 min. For soaking times varying from 25 min to109 min there was only a slight drop in the ulti-mate strength. However, beyond 110 min theultimate strength appeared to decrease again as thesoaking time was increased further. Since soakingtimes greater than 25 min would seldom be usedin standard shop and field practice, except underunusual circumstances, the values of strength forthese large soaking times are reported only as amatter of interest. Figure 11(b) shows values ofultimate strength for the more practical range ofsoaking times.

It may be observed also in Fig. 11 and Table 4that the driving time had no consistent effect onthe ultimate strength of the rivets and that therivets heated at 1800 F gave only slightly higherultimate strengths than those heated at 1875 F.

Most structural fabricating shops heat theirrivets until they reach a cherry red color beforedriving and then drive the rivets until a full headis formed. However, a survey of some of the largestfabricators produced very little information regard-ing the temperature or the length of soaking timemost commonly used by these fabricators; oneauthority suggested that a general rule of thumbwas to soak the rivets 5 min per 1/s-in. diam.

In view of the data of Table 4 and Fig. 11 andconsidering the information obtained from fabri-cators as to the standard shop and field practicefor hand-pneumatic driven rivets, it was decidedto use the following conditions for the hand-pneumatic driven rivets of the test program.

Rivet Furnace Soaking DrivingDiameter Temperature Time Time

In. Deg F Min Sec% 1850 18 187% 1850 21 201 1850 24 22

The furnace temperature of 1850 F is 100 de-grees less than the maximum temperature allowedin the AISC Specifications, and the driving time isslightly greater than the time required to form afull head.

8. Variation in Ultimate Strength With Shear-Tension Ratio

A number of the preliminary rivet tests wereperformed for the purpose of studying the variationin ultimate strength with shear-tension ratio. Allof the rivets were of the rimmed steel, 7/8 -in. diam,2-in. grip, heated in an electric furnace at 1800 Ffor 21 min, and hand-pneumatic driven for 20 sec.

The results of these tests, at various shear-tension ratios, are summarized in Table 5. Columns(4) and (5) give the ultimate rivet strengths basedon the nominal rivet area and the area of the rivethole respectively. A very convenient and informa-tive manner of presenting these data is in the formof an interaction curve, which illustrates the rela-tionship between the tensile and shear componentsof the ultimate strength of the rivets. In such apresentation the ordinate for each test is propor-tional to the tensile component, the abscissa isproportional to the shear component, and the radialdistance provides a measure of the resultantstrength of the rivet.

This interaction relationship may be based onthe tensile, shear, or coupon strength of the rivets,which have merits depending upon the applicationof each. Some persons might be most interested in

Table 5Results of Preliminary Tests at Various Shear-Tension Ratios

Spec. Shear-Tension Ultimate Ultimate Strength Ultimate Strength Ultimate StrengthNo. Ratio Load, Based on Nominal Based on Hole of Rivet -

lb Rivet Area, Area, psi Ultimate Strengthpsi of Rivet in

Tension(1) (2) (3) (4) (5) (6)P-8 1.0:0.0 37,050 61,600 53,600 0.708P-7 1.0:0.268 36,600 60,900 53,000 0.700P-6 1.0:0.577 38,770 64,400 56,100 0.741P-11 1.0:0.668 38,700 64,400 56,100 0.741P-5 1.0:1.0 41,350 68,700 59,900 0.791P-9 0.668:1.0 43,700 72,800 63,300 0.836P-4 0.577:1.0 48,300 80,300 70,000 0.925P-10 0.415:1.0 49,100 81,700 71,100 0.939P-3 0.268:1.0 50,700 84,300 73,500 0.971P-1 0.0:1.0 52,350 86,800 75,700 1.000

* Ultimate Stress obtained from Standard 0.505-in. Coupon Tests =63,250 psi.NOTE: Rivet Material: Rimmed Steel

Rivet Diameter: / in.Rivet Grip: 2 in.Furnace Temperature: 1800 FHand-Pneumatic Driving Time: 20 seeSoaking Time: 21 min

Ultimate Strengthof Rivet-

Ultimate Strengthof Rivet in

Shear(7)

1.0000.9881.0461.0461.1161.1791.3041.3251.3681.413

Col. (5) +Ultimate Tensile

Strength ofRivet StockMaterial*

(8)0.8470.8380.8870.8870.9471.0011.1071.1241.1621.197


the data interpreted on the basis of the couponstrength. Designers, however, would probably beprimarily interested in the relationship based on 1.0:0.0the shearing strength of the rivets; others may bemore concerned with the tensile strength relation-ship. Nevertheless, in each case, the same generalpicture is obtained.

The strength-tension and strength-shear rela- 1.0:0.268

tionships for the various tests are presented incolumns (6) and (7) of Table 5 respectively, andin Fig. 12. Ellipses, having as semi-major axis theultimate strength of the rivet in tension divided 1.0:0.577by the rivet tensile or shear strength, and as semi-minor axis the ultimate strength of the rivet inshear divided by the rivet tensile or shear strength,agree quite closely with the results of the test data. 1.0:0.668The maximum deviation from these ellipses occursat a shear-tension ratio of 0.668:1.0 and is onlyabout 4 per cent.

The strength of the rivets (based on the area ofthe hole) divided by the coupon strength (0.505-in. 1.0:1.0

0

0

0

0

-0(0

4..0

-0

04..

(0

04

4-,)004

04

0.668:1.0

0.577:1.0

0.415:1.0

0.268:1.0

0.0:1.0

Fig. 12. Interaction Curves for Preliminary Tests Fig. 13. Fractures of Specimens Tested at

at Various Shear-Tension Ratios Various Shear-Tension Ratios

IShear component

Rivet tens7/e strength or rivet shear strength


Fig. 14. Interaction Curve for Preliminary Specimens Tested at

Various Shear-Tension Ratios, Based on Coupon Strength

48 52 56 60 64 68 72 76Ullmate strength in /000 lb per sq in. based on hole diam

Fig. 15. Effect of Shear-Tension Ratio on UltimateStrength of Rivets

coupons) is given in column (8) of Table 5 andplotted in Fig. 14. This figure is similar to Fig. 12except that the scale factor is based on the tensilecoupon strength of a standard 0.505-in. diam speci-men instead of the tensile or shear strength of therivet. Figure 14 has the advantage of correlatingthe rivet strength at the various shear-tensionratios with coupon strength of the rivet material.

Deformation measured normal to rivet axis

Fig. 16. Deformation Measured Normal to Rivet Axis for Preliminary Tests

5

S7/g in. rimmed steelrivets, 2 in. grip

2

*~

0 * .. ____ ___ ___ ___ __ ^** .


However, this correlation, it should be realized,is affected to some extent by the heating and driv-ing of the rivet material; in the present tests, anincrease of approximately 20 per cent was obtainedin the tensile strength as a result of the driving.

The effect of the shear-tension ratio on theultimate strength of the preliminary specimens isshown also in Fig. 15. For loadings between shear-tension ratios of infinity (shear alone) and 2.0,little change occurred in the ultimate strength ofthe rivets; however, for loadings between shear-tension ratios of 2.0 and zero (tension alone), arelatively large increase occurred in the ultimatestrength of the rivets. The corresponding ultimatestrengths based on the area of the rivet hole forthe three shear-tension ratios of infinity, 2, andzero are 53,600, 55,000 and 75,700 psi respectively.

Examples of the fracture surfaces obtained inthe tests at the various shear-tension ratios areshown in Fig. 13. The top rivet in the figure was

tested in shear alone, while the remaining rivetsfrom top to bottom had progressively decreasingshear-tension ratios. It can be seen that the frac-ture type and the deformation changed materiallyas the loading was varied from shear to tension.

Stress-elongation or deformation curves for thetests at various shear-tension ratios are shown inFigs. 16 and 17. As would be expected, there wasalmost no axial elongation in the direct shear testsuntil stresses were reached that produced largeshear distortions. However, the shearing deforma-tions normal to the axis of the rivets for all of therivets, except the one tested in direct tension, wererelatively large, even at the lower stresses. Thismeasured deformation was not the actual rivet dis-tortion normal to the rivet axis since it includedslip and also some elastic action in the jig andtesting apparatus; nevertheless, the measurementdoes show the relative movements that occurredduring the tests at various shear-tension ratios.

Total axial elongation of rivet

Fig. 17. Axial Elongation for Rivets of Preliminary Tests

IV. RESULTS AND ANALYSIS OF SHEAR-TENSION TESTS

An outline of the tests in the principal testprogram is given in Table 6. Four different shear-tension ratios (1) 1.0:0.0, (2) 1.0:0.577, (3) 0.577:1.0, and (4) 0.0:1.0, were used in each series, cor-responding to directions of loading in the testfixture of 90, 60, 30, and 0 degrees with respect tothe axis of the rivets. The other variables in theprogram included the rivet size, grip, method ofdriving and the method of rivet manufacture. Foreach particular rivet diameter and shear-tensionratio of any series, two or three identical specimenswere tested, depending upon the agreement in theresults of the first two tests.

A numbering system, indicating the test condi-tions, was used for the individual test specimens.For example: (4a 7 - 2). The first digit refers tothe series number given in Table 6, the followingletter refers to the shear-tension ratio (see Table3 and Fig. 8), and the next digit refers to the rivetdiameter in eighths of an inch. The final numberdifferentiates between identical specimens.

9. Results of Tests

A total of 403 tests were conducted to studythe strength of rivets under combined shear andtension. In the analysis of the results of these teststhe ultimate rivet strength has been used as thebasis of comparison. The test data, presented inTables 7 to 14 inclusive, give values of ultimate

Table 6Outline of Test Program

Series Grip, Method of Method of RivetNo.* in. Drivingt Manufacture

1 1 Hand Pneumatic Cold-Formed2 1 Hand Pneumnatic Hot-Formed3 5 Hand Pneumatic Cold-Formed4 5 Hand Pneumatic Hot-Formed5 2 Hand Pneumatic Cold-Formedj6 3 Hand Pneumatic Cold-Formed$9 5 Machine Cold-Formed

10 5 Machine Hot-Formed

* Each series of tests was conducted on -, 7%-, and 1-in. rivets and at

the following shear-tension ratios.(a) = 1.0:0.0(c) = 1.0:0.577(e) = 0.577:1.0(g) = 0.0:1.0

t Hand-pneumatic driven rivets were driven in the University of Illinois'Structural Research Laboratory. Machine driven rivets were driven in alarge structural steel fabricating shop.t Used type of rivets giving lowest values in Series No. 1, 2, 3, and 4.

Table 7Summary of Test Results of Series I

GRIP: 1 IN. DRIVING: HIAND-PNEUMATIC RIVETS: COLD-FORMED

la 6-3ia 6-4la 7-3la 7-6la 8-3la 8-10Averagele 6-8lc 6-10Ic 7-10Ie 7-21c 8-8le 8-6Averagele 6-91e 6-6le 7-41c 7-8le 8-9le 8-7Average1g 6-2Ig 6-7Ig 7-5ig 7-71g 8-5lg 8-4Average

Shear-TensionRatio

1.0:01.0:01.0:01.0:01.0:01.0:0

1.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.577

0.577:1.00.577:1.00.577:1.00.577:1.00.577:1.00.577:1.0

0:1.00:1.00:1.00:1.00:1.00:1.0

UltimateLoad,

lb

25,00025,05032,55032,75042,40041,350

25,87025,15033,25033,00042,30041,800

30,20029,35036,85037,95050,55049,000

32,43033,65042,32042,75056,13056,200

Ultimate Strength Based OnNominal Hole

Area, Size,psi psi

56,500 48,25056,610 48,34054,190 47,20054,530 47,49054,060 47,90052,720 46,720

54,770 47,65058,460 49,93056,840 48,54055,360 48,21054,940 47,85053,900 47,80053,290 47,200

55,470 48,25068,250 58,28066,330 56,65061,350 53,43063,190 55,03064,450 57,12062,480 55,370

64,340 55,98073,290 62,59076,050 64,94070,460 61,36071,180 61,99071,560 63,42071,650 63,500

72,360 62,970

Table 8Summary of Test Results of Series 2

GRIP: 1 IN. DRIVING: HAND-PNEUMATIC RIVETS: HOT-FORMED

Spec. Shear- Rivet Ultimate Ultimate Strength Based OnNo. Tension Size, Load, Nominal Hole

Ratio in. lb Area, Size,psi psi

2a 6-7 1.0:0 25,200 56,950 48,6402a6-4 1.0:0 V4 23,800 53,790 45,9302a 7-3 1.0:0 %s 31,500 52,450 45,6802a 7-4 1.0:0 V% 32,200 53,610 46,6902a 8-6 1.0:0 1 39,600 50,490 44,7502a 8-7 1.0:0 1 39,050 49,790 44,120Average 52,840 45,9702c 6-10 1.0:0.577 34 27,030 61,090 52,1702c 6-9 1.0:0.577 /4 26,800 60,570 51,7202c 7-7 1.0:0.577 7% 34,280 57,080 49,7002c 7-6 1.0:0.577 t% 32,300 53,780 46,8302c 8-9 1.0:0.577 1 40,400 51,510 45,6502c 8-5 1.0:0.577 1 40,930 52,180 46,250Average 56,040 48,7202e 6-6 0.577:1.0 Y4 31,750 71,750 61,2802e 6-3 0.577:1.0 %4 31,820 71,910 61,4102e 7-1 0.577:1.0 % 39,000 64,930 56,5502e 7-9 0.577:1.0 7% 39,620 65,970 57,4502e 8-8 0.577:1.0 1 47,380 60,410 53,5402e 8-10 0.577:1.0 1 47,330 60,340 53,480Average 65,880 57,2802g 6-5 0:1.0 4 36,000 81,360 69,4802g 6-2 0:1.0 % 33,260 75,170 64,1902g 7-8 0:1.0 7% 45,500 75,760 65,9802g 7-10 0:1.0 % 44,400 73,930 64,3802g 8-2 0:1.0 1 56,280 71,760 63,5902g 8-3 0:1.0 1 56,200 71,650 63,500Average 74,940 65,190



GRIP: 5 IN. DRIVING: HAND-PNEUMATIC RIVETS: COLD-FORMED


Ratio in. lb Area, Size,psi psi

3a 6-2 1.0:0 Y4 22,750 51,410 43,9003a6-4 1.0:0 4 22,770 51,460 43,940

3a 7-9 1.0:0 Y% 29,700 49,450 43,0603a 7-6 1.0:0 Y% 30,370 50,566 44,0403a 8-6 1.0:0 1 40,200 51,255 45,4203a8-9 1.0:0 1 39,400 50,235 44,520

Average 50,730 44,146

3c 6-10 1.0:0.577 Y4 22,820 51,570 44,0403c 6-5 1.0:0.577 Y4 23,300 52,660 44,9703c 7-4 1.0:0.577 %/8 29,500 49,100 42,7703c 7-10 1.0:0.577 %/ 29,600 49,280 42,9203c 8-3 1.0:0.577 1 40,350 51,440 45,5903c 8-5 1.0:0.577 1 39,470 50,320 44,600

Average 50,728 44,150

3e 6-9 0.577:1.0 3/ 26,250 59,320 50,6603e 6-6 0.577:1.0 •4 27,500 62,150 53,0703e 7-3 0.577:1.0 Y 36,700 61,100 53,2103e 7-8 0.577:1.0 % 35,450 59,024 51,4003e 7-5 0.577:1.0 Y% 35,340 58,840 51,2403e 8-4 0.577:1.0 1 46,670 59,500 52,7403e 8-7 0.577:1.0 1 46,150 58,840 52,150

Average 59,825 52,0703g6-7 0:1.0 Y4 28,700 64,860 55,3903g6-8 0:1.0 4 29,600 66,900 57,1303g 6-3 0:1.0 Y4 28,000 63,280 54,0403g7-2 0:1.0 Ys 39,400 65,600 57,1303g7-7 0:1.0 Y 38,900 64,770 56,4003g8-2 0:1.0 1 49,500 63,100 55,9303g8-8 0:1.0 1 50,100 63,870 56,610

Average 64,625 56,090

strength computed for the nominal rivet area andthe area of the rivet hole for four shear-tensionratios for each series of tests; the rivet grip, themethod of driving, and the method of rivet manu-


GRIP: 5 IN. DRIVING: HAND-PNEUMATIC RIVETS: HOT-FORMED

Spec. Shear-No. Tension

Ratio

4a 6-2 1.0:04a 6-3 1.0:04a 7-2 1.0:04a 7-5 1.0:04a 7-8 1.0:04a 8-1 1.0:04a8-

2 1.0:0

4a8-11 1.0:0Average4c 6-10 1.0:0.5774c 6-9 1.0:0.5774c 7-3 1.0:0.5774c 7-6 1.0:0.5774c 8-8 1.0:0.5774c 8-3 1.0:0.5774c 8-10 1.0:0.577

Average4e 6-8 0.577:1.04e 6-11 0.577:1.04e 7-4 0.577:1.04e 7-10 0.577:1.04e 7-9 0.577:1.04e 8-7 0.577:1.04e 8-6 0.577:1.0Average

4g 6-7 0:1.04g 6-5 0:1.04g 6-1 0:1.04g 7-11 0:1.04g 7-7 0:1.04g 7-1 0:1.04g 8-9 0:1.04g8-4 0:1.04g8-5 0:1.0Average

UltimateLoad,lb

22,68023,15032,10031,30031,28038,10038,65039,870

22,80022,45031,80031,02038,86037,40038,750

27,54026,90040,10036,90037,30046,00046,700

29,25029,85029,11040,82040,35041,00049,91049,00050,450

Ultimate Strength Based OnNominal

Area,psi

51,20052,20053,40052,10052,00048,60049,30050,800

51,200

51,50050,60052,90051,60049,50047,70049,30050,440

62,20060,80066,70061,40062,00058,60059,50061,600

66,00067,40065,70068,00067,20068,20063,70062,50064,30065,890

HoleSize,psi

43,80044,60046,50045,40045,40043,10043,70045,00044,69044,00043,30046,20045,00043,80042,30043,70044,04053,10051,80058,10053,50054,10052,00052,800

53,63056,40057,60056,20059,30058,50059,40056,50055,40057,000

57,370


GRIP: 2 IN. DRIVING: HAND-PNEUMATIC RIVETS: COLD-FORMED


Ratio

5a 6-9 1.0:05a 6-11 1.0:05a 7-5 1.0:05a 7-4 1.0:05a 8-2 1.0:05a 8-5 1.0:0Average

5c 6-75c 6-105c 7-85c 7-95c 8-95c 8-4Average

5e 6-85e 6-25e 7-75e 7-65e 8-15e 8-6Average

5g 6-55g 6-15g 7-15g 7-105g 8-85g 8-7Average

RivetSize,in.

V4

11

1.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.577

0.577:1.00.577:1.00.577:1.00.577:1.00.577-1.00.577:1.0

0:1.00:1.00:1.00:1.00:1.00:1.0

UltimateLoad,

lb

24,15024,50031,94031,02040,95040,500

24,80024,35031,25030,75039,85040,600

29,48028,80037,78037,18049,22048,630

32,37033,42041,27041,25054,00053,120


Area, Size,psi psi

54,580 46,61055,370 47,28053,180 46,31051,650 44,98052,210 46,27051,640 45,760

53,100 46,200

56,05055,03052,03051,20050,81051,76052,810

66,62065,09062,890061,90062,75062,00063,540

73,16075,53068,71068,68068,85067,73070,440

47,86046,99045,31044,59045,03045,880

45,940

56,89055,58054,78053,91055,62054,95055,290

62,47064,50059,84059,81061,02060,02061,280

facture have been separated by presenting eachseries individually.

Figure 18 shows four fractures which are

typical of those obtained in the tests at the four

shear-tension ratios. From left to right the shear

tension ratios for the specimens shown are 0.0:1.0,

0.577:1.0, 1.0:0.577, and 1.0:0.0.


GRIP: 3 IN. DRIVING: IHAND-PNEUMATIC RIVETS: COLD-FORMED


6a 6-56a 6-96a 7-96a 7-36a 8-36a 8-6Average

6e 6-76c 6-36c 7-86c 7-76c 8-16c 8-8Average

6e 6-66e 6-46e 7-56e 7-76e 8-106e 8-7Average

6g 6-16g 6-86g 7-16g 7-46g 8-46g 8-5Average

Ratio

1.0:01.0:01.0:01.0:01.0:01.0:0

1.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.577

0.577:1.00.577:1.00.577:1.00.577:1.00.577:1.00.577:1.0

0:1.00:1.00:1.00:1.00:1.00:1.0

in.

11

lb

24,14023,92030,90030,70040,24040,050

24,05023,90031,15031,85041,40040,280

28,53028,50038,04038,19047,70049,900

31,60033,08041,87041,10053,37053,450

Area, Size,psi psi

54,550 46,59054,060 46,160

51,450 44,80051,110 44,51051,310 45,47051,070 45,26052,260 45,460

54,35054,01051,86053,03052,78051,360

52,900

64,48064,41063,33063,58060,82063,62063,370

71,40074,76069,71068,43068,05068,15070,080

46,42046,13045,17046,18046,78045,51046,030

55,06055,00055,16055,37053,90056,39055,150

60,99063,84060,71059,59060,31060,40060,970


7,

0

0

'700-PC

*1.

b00

Fig. 18. Typical Fractures at the FourShear-Tension Ratios

During the application of load to each speci-men, the separation of the testing machine pull-heads was recorded. Typical results of these meas-urements are shown in Fig. 19 for tests conductedat the four shear-tension ratios. The areas underthese curves give an indication of the relativeenergy absorbing capacity of the rivets when sub-jected to static loads. It is interesting to note thata deviation in loading from direct tension to ashear-tension ratio of 0.577:1.0 greatly reducedthe energy absorbing capacity of the rivets.

10. Effect of Shear-Tension Ratio

The results of the shear-tension tests are sum-marized in Table 15 for each series of tests and


GRIP: 5-IN. DRIVING: MACHINE


Ratio

9a 6-1 1.0:09a 6-6 1.0:09a 7-1 1.0:09a 7-6 1.0:09a 8-1 1.0:09a 8-

6 1.0:0

Average

9e 6-5 1.0:0.5779e 6-4 1.0:0.5779c 7-7 1.0:0.5779c 7-8 1.0:0.5779c 8-3 1.0:0.5779c 8-9 1.0:0.577Average9e 6-7 0.577:1.09e 6-3 0.577:1.09e 7-3 0.577:1.09e 7-9 0.577:1.09e 8-7 0.577:1.09e 8-8 0.577:1.0Average9g6-2 0:1.09g6-

8 0:1.0

9g7-2

0:1.09g7-4 0:1.09g8-4 0:1.09g8-10 0:1.0Average

UltimateLoad,

lb

22,33022,05029,60028,60037,25037,750

23,20023,22028,90029,50037,34037,150

27,03027,50034,00034,80043,48044,270

28,73029,43039,13037,90048,44048,200

RIVETS: COLD-FORMED


Area, Size,psi psi

50,465 43,09049,830 42,55049,380 43,01047,620 41,47047,490 42,09048,130 42,66048,820 42,48052,430 44,78052,480 44,81048,120 41,90049,120 42,77047,600 42,19047,370 41,98049,520 43,07061,090 52,17062,150 53,08056,610 49,30057,940 50,46055,440 49,13056,440 50,02058,280 50,69064,930 55,45066,510 56,80065,150 56,74063,100 54,95061,760 54,74061,450 54,47063,820 55,520

Deformation in inches, separotion of pu//-heads

Fig. 19. Typical Load-Deformation Curves for RivetsTested at Various Shear-Tension Ratios

each of the shear-tension ratios. For all series, theaverage ultimate strength based on the rivet holearea is given in column (3). The interaction databased on the tensile strength and the shear strengthof the rivets are given in columns (4) and (5),respectively. With these values the data can beexpressed in the form of interaction curves asdescribed in the section on "Variation in UltimateStrength With Shear-Tension Ratio."

The column (4) data of Table 15 are compared,in Table 16(a), with the corresponding values froman ellipse having a semi-major axis of unity and a


GRIP: 5-IN.

Spec.No.

10a 6-1 110a 6-1 110a 7-1 110a 7-10 11

0a 7-11

lOa 8-1 1lOaS -11 1Average

10e 6-4 110c 6-6 110c 7-3 110c 7-5 110e 8-4 110e 8-6 1Average

10e 6-7 010e 6-8 0103 7-6 010- 7-7 010e 8-5 C10a 8-7 0Average

10g 6-2 C1

0g 6-9 C

10g 7-4 Co10g 7-9 C

10g 8-2 C10g 8-10 CAverage

Shear-TensionRatio

1.0:01.0:01.0:01.0:0.0:0

1.0:0.0:0

.0:0.577

.0:0.577

.0:0.577

.0:0.577

.0:0.577

.0:0.577

.577:1.01.577:1.01.577:1.01.577:1.01.577:1.0.577:1.0

:1.0:1.0

1:1.0:1.0

1:1.01: 1.0

DRIVING:

RivetSize,in.

Y4Y47/

11

1

1Y8

MACHINE

UltimateLoad,

lb

23,35022,95030,15029,00027,55037,00036,400

23,78023,90030,17029,60037,88038,500

27,85027,82035,32035,52044,15043,770

29,91030,30038,76038,95048,32048,600

RIVETS: IOT-FORMED


Area, Size,psi psi

52,770 45,07051,870 44,29050,200 43,72048,280 42,05045,870 39,95047,180 41,81046,410 41,13048,940 42,570

53,740 45,89054,010 46,13050,230 43,75049,280 42,92048,300 42,80049,090 43,500

50,770 44,160

62,940 53,75062,870 53,69058,810 51,21059,140 51,50056,290 49,89055,800 49,46059,310 51,580

67,590 57,73068,480 58,48064,530 56,20064,850 56,48061,610 54,60061,960 54,92064,840 56,400


Series Shear-TensionNumber Ratio

(2)1.0:0.01.0:0.01.0:0.01.0:0.01.0:0.01.0:0.01.0:0.01.0:0.0Average

1.00:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.5771.0:0.577Average

0.577:1.00.577:1.00.577:1.00.577:1.00.577:1.00.577:1.00.577:1 .00.577:1.0Average

0.0:1.00.0:1.00.0:1.00.0:1.00.0:1.00.0:1.00.0:1.00.0: 1.0Average

semi-minor axis ofto semi-minor axis

Ult. StrengthBased on Hole

Area, 1000'spsi(3)

47.6545.9744.1544.6946.2045.4642.4842.57

44.89

48.2548.7244.1544.0445.9446.0343.0744.1645.54

55.9857.2852.0753.3655.2955.1550.6951.58

53.92

62.9765.1956.0957.3661.2860.9755.5256.40

59.47

Col. (3) +Ult.Strength of

Rivet inTension

(4)0. 7570. 7050.7870.7790.7540.7460.7650.7550.756

0, 7660.7470.7870.7700.7490.7550.7760.7830. 767

0.8890.8790.9280 9300.9020.9040.9130.9150. 907

1.01.01.01.0

1.01.01.01.0

Col. (3) +Ult.Strength of

Rivet inShear

(5)1.01.01.01.01 01.01.01.01.0

1.0121.0591. 0000. 9900.9941.0131.0141 .0351.015

1.1751.2451.1801.1951.1971.2141 .1931.2081.201

1.3211.4181.2731.2851. 3261,3411 3411 .3221 324

0.75. This ratio of semi-majoris equal to the ratio of allow-

able shear and tensile strengths permitted by thepresent AISC specification, and is in reasonablygood agreement with the test results. The maximumdeviation from the ellipse for any series is - 6.0per cent and occurs for Series 2 (1-in. grip, hand-pneumatic driven) at a shear-tension ratio of1.0:0.0. At this same shear-tension ratio, the devia-tion of the average value of all tests from thevalue given by the theoretical ellipse is only 0.8per cent. It may be of interest also to note that 98per cent of all of the individual test results differedby less than 7.0 per cent from the values predictedby the ellipse,

y2 X 2

(1.0) 2 ± (0.75)2= 1.0

based on the average tensile strength of the driven

rivets. Although this type of interaction curve fits

the test data extremely well, it must be remem-

bered that the values are all functions of the rivet

tensile strength.The data of column (5) of Table 15 are com-

pared with a similar ellipse in Table 16(b). The

Table 15Average Interaction Data for All Series of Tests

Table 16Comparison of Interaction Data With Ellipse

(A) BASED ON RIVET TENSILE STRENGTH

SeriesNo.

23456910

AverageEllipse

S::= 0.577:1.0Av.for

Series

0.8890.8790,9280.9300.9020.9040.9130.9150.9070.912

% Devia-tion from

Ellipse

-2.5-3.6+1.7+2.0-1.1-0.9+0.1+0,3-0.5

S:T =1.0:0.577 S:T= 1.0:0.0% Devia-tion from

Ellipse

-3.3-5.7-0.6-2.8-5.4-4.7-2.0-1.1-3.2

Av.for

Series

0.7570.7050.7870.7790,7540, 7460.7650.7550.7560.750

Av.for

Series

0.7660.7470.7870.7700.7490.7550.7760.7830.7670.792

(B) BASED ON RIVET SHEAR STRENGTH

Series S:T=0:1.0 S:T =0.577:1.0 S:T=No. Av. % Devia- Av. % Devia- Av.

for tion from for tion from forSeries Ellipse Series Ellipse Series

1 1,321 -0.9 1.175 -3.6 1.0122 1.418 +6.4 1.245 +2.1 1.0593 1.273 -4.8 1,180 -3.2 1.0004 1.285 -3.7 1.195 -2.0 0.9905 1.326 -0.5 1.197 -1.7 0.9946 1.341 +0.6 1.214 -0.4 1.0139 1.307 -2.0 1.193 -2.1 1.014

10 1.322 -0.8 1.208 -0.9 1.035

Average 1.324 -0.7 1.201 -1.0 1.015

Ellipse 1.333 1.219 1.060

% Devia-tion fromEllipse

+0.9-6.0+4.9+3.9+0.5-0.5+2.0+0.7

+0.8

1.0:0.577% Devia-tion fromEllipse

-4.5-0.1-5.7-6.6-6.2-4.4-4.3-2.4-4.3

semi-mninor axis of this ellipse was taken as unityand the semi-major axis as 1.333. This is the sameratio of shear to tension as was used in the pre-ceding analysis, but the present comparison isbased on the average shear strength of the drivenrivets rather than the tensile strength.

The maximum deviation of the data of anyseries from the ellipse occurs at a shear-tensionratio of 1.0:0.577 and is - 6.6 per cent. However,the average deviation for all of the series, at thissame shear-tension ratio, is only - 4.3 per cent.At a shear-tension ratio of 0.577:1.0 the deviationis only - 1.0 per cent, and at a shear-tension ratioof 0.0:1.0 only 0.7 per cent.

In Fig. 20 the data are plotted on the basis ofthe rivet shear strength. Each point on this figurerepresents the average of the duplicate specimensof the three rivet diameters tested at a particularshear-tension ratio, and the number at each pointrefers to the particular series number that the pointrepresents. This presentation, it appears, will be ofmost practical use to the design engineer since itcorrelates the results of the tests with the shearstrength of the rivets, a value with which he iswell acquainted.

If one assumes that this curve of Fig. 20 isrepresentative of the data and the behavior of therivets, the strength of a rivet subjected to a loadingat any shear-tension ratio can then be convenientlyexpressed as a function of the direct shear strength


A = Average

.56 r--r--

Shear component - rivet shear strength

Fig. 20. Interaction Curve for Rivets of all Series of Primary Test Program


of the rivets. From the ellipse the strength of arivet at any shear-tension ratio is given by theequation,

y2 x+(1.333)2 (1.0) 2

where y =

and x =

Tensile component of force on rivetat ultimate strength

Ultimate shear strength of rivet

Shear component of force on rivetat ultimate strength

Ultimate shear strength of rivet

Let r = the strength of a rivet divided by therivet shear strength at any tension-shear ratio, m.

y = mx.

Solving Eqs. 2 and 3 simul-taneously for a value of x,one obtains:

S(1.333) 2

x \ m2 + (1.333)2 (4)

Then solving for a value of r, one obtains,

I + M- ( 5)r = 1.333 (1.333) 1 m . (5)

Since r is the rivet strength at any tension-shearratio divided by the rivet shear strength, we canwrite,

S = r S (6)

where S = strength of a rivet at any tension-shearratio; 8, = shear strength of the rivet; and rranges from a value of 1.0 for a rivet subjected todirect shear to a value of 1.333 for a rivet sub-jected to direct tension. Values of r, the interactioncoefficient, for various tension-shear ratios may becomputed from the above equation or obtaineddirectly from the curve shown in Fig. 21.

11. Effect of Grip

A study of the effect of the grip on the ultimatestrength of the rivets at the four shear-tension ra-tios is shown in Fig. 22. All of the rivets whoseultimate strength is shown in this figure were cold-formed and hand-pneumatic driven. Each rivet di-ameter is shown separately; thus the rivet grip is

40

3.0

2.0

1.0

nS/./ li2 0.3

Interact/on coefficient, r

Fig. 21. Relation of Interaction Coefficient toTension-Shear Ratio

the only variable contributing to the difference instrengths shown by the curves.

In general, the ultimate strength decreased withan increase in grip; however, the decrease wassomewhat more pronounced for the tests in directtension than for the tests at the other shear-tensionratios. For the direct tension tests of 3/-in. rivetsat grips varying from 1 in. to 5 in., the decrease inultimate strength was 12.4 per cent. For tests madeat shear-tension ratios of 0.577:1.0, 1.0:0.577, and1.0:0.0, the corresponding decreases in ultimatestrength for the 3%-in. rivets were 9.8, 9.4, and 9.2per cent, respectively. Similar decreases in strengthare shown also for the 7/s-in. and 1-in. rivets.

A study of the rivet sections shown in Figs. 3, 4,and 5 shows that the rivets of the 5-in. grip speci-

* mens did not fill the rivet holes as well as did the1- and 2-in. grip rivets. This fact may be respon-sible in part for the lower ultimate strengths ob-tained for the 5-in. grip specimens. It is possiblealso that the short grip rivets have slightly differ-ent strength properties than those of long grips be-cause of the differences in working the materialduring driving.

There may be some question as to the effect ofthe initial clamping force in the rivets upon theirbehavior when subjected to combined shear andtension, since long grip rivets are known to have agreater initial tension than those with a short grip.However, it is believed that upon yielding, theeffect of this clamping is removed and the ultimate

I


strength of the rivets, whether subjected to tensionor shear, or a combination of tension and shear, isnot affected by the clamping.

12. Effect of Rivet Diameter

The variation in the ultimate strength of therivets with a variation in the diameter, for eachseries of tests, is shown in Fig. 23. Apparently, theeffect of a change in the diameter of a rivet on itsstrength was less pronounced for tests in directshear (shear-tension ratio of 1.0:0.0) than for testsmade at other shear-tension ratios. However, inspite of the small variation, the scatter of test re-sults between different series was less for tests madein direct shear than for tests made at other shear-tension ratios.

In the tests of series 1, 2, 9 and 10, the 3%-in.rivets were slightly stronger than the 7/s-in. and1-in. rivets; for series 5 and 6 the 3 -in. and 1-in.rivets were somewhat stronger than the %/8-in.rivets; but for series 4 the 7/s-in. rivets were thestrongest of the three diameters. These variations

S

0-0

0

'0

0

-0

0.

-0

0

0S

in strength with rivet diameter were consistent forthe tests made at each shear tension ratio. Althoughthere appears to be a trend for the strength to de-crease with an increase in rivet diameter, it is ob-vious that there was no large or consistent effect.With the exception of series 2, the effect of rivetdiameter on ultimate strength was small; none ofthe strengths of the various series differed by morethan approximately 7 per cent. However, series 2had a maximum variation in strength between the3%-in. and 1-in. rivets of 12.8 per cent. This maxi-mum variation in strength occurred at a shear-tension ratio of 0.577:1.0.

13. Effect of Rivet Manufacture and Fabrication

The variation in the ultimate strengths of therivets tested at the four different shear-tensionratios with the method of rivet manufacture (hot-formed or cold-formed) is shown in Fig. 24. Theeffects of rivet grip, rivet diameter, and method ofdriving have been separated in this comparison sothat the effects of the method of rivet manufacture

Grip in inches

Fig. 22. The Effect of Rivet Grip on Ultimate Strength at Four Different Shear-Tension Ratios


can be conveniently studied. For the tests in directshear, the 1-in. grip, cold-formed rivets appear tohave been slightly stronger than the hot-formedrivets, but in general the hot-formed rivets wereabout equal in strength or slightly stronger thanthe cold-formed rivets. In no case, however, wasthere more than 5.2 per cent difference in ultimatestrength between the hot- and cold-formed rivets.

Figure 24 also demonstrates the difference instrength between the hand-pneumatic and machinedriven rivets which had a 5-in. grip. The machinedriven rivets were slightly weaker than the hand-pneumatic driven rivets; however, this slight differ-ence is insignificant and could, very likely, resultfrom differences in heating and soaking conditions.

14. Discussion of Possible Design Rules

While the various design specifications providea working or allowable stress for rivets subjectedto shear, few provide for the use of rivets in ten-

at23

ci,cc-ccci

'7,

'ticci,'ci

ccccc.ci

'ci'cici,

'ci

ci,

cca

sion. On the basis of the tests reported here, as wellas many other tests reported in the literature, it isapparent that rivets will withstand tension or acombination of tension and shear, and that simpleempirical relationships can be developed to relatethe strength of these rivets to their shearing ortensile strength.

In 1928 Young and Dunbart proposed a rela-tionship, based on laboratory tests, which providesfor a permissible tensile stress on rivets subjectedto tension and shear. This relation provides a factorof safety of about 4 against failure and is asfollows:

Pt = 21,000 - 8,000 d - 6750 (V T 2*( T'

where Pt = permissible tensile stress on rivets, psiT' = total tension on rivet

V' = total shear on rivet

d = diameter of rivet before driving

Rivet di'om, inches Rivet diam, inches

Fig. 23. Effect of Rivet Diameter on Ultimate Strength at Four Different Shear-Tension Ratios


a - / in. diam - / in. diam

55

6- 0577: 1.0

50 T ^------- I ------ \

451O : 0_577

5 1.0 : 0.0

Cold Hot Cold Hot Cold HotIin. grip, hand 5 in. grip, hand Sin. grip, machine

Fig. 24. Effect of Method of Rivet Manufacture andFabrication on Ultimate Strength at Four

Different Shear-Tension Ratios

Several forms of the interaction relationshipswhich have been suggested for allowable workingstresses on rivets subjected to shear and tensionare shown in Fig. 25, and demonstrate the ease withwhich they can be used to determine allowablecombined stresses on a rivet. Curve (1) is of theform suggested by Young and Dunbart but basedon an allowable tensile stress of 20,000 psi, curve(2) is the elliptical relationship which has beenfound to be representative of the test results pre-sented herein, and curve (3) is a straight-line rela-

t "Permissible Stresses on Rivets in Tension," by C. R. Youngand W. B. Dunbar. Bulletin No. 8, University of Toronto, Faculty ofApplied Science and Engineering, 1928.

Shear-tension ratioS0: 10

v, Allowable shear, psi

I. p = 20,000-6,750 ( /xy

. p 15,0002. p-=

3. p - 30,000-167v

Fig. 25. Comparison of Various Relationships

for Allowable Unit Stresses

tionship suggested by Higgins and Munse* as a

simple alternative for the ellipse. The values from

the elliptical relationship can also be presented in

tabular form as shown in Table 17. Thus, it can beseen that design specifications could be developedreadily to provide for the design of rivets subjectedto combined shear and tension.

Table 17Working Shear-Tension Stress for Rivets*

(Based on an allowable stress for shear alone of 15 ksi)

Angle, Tension- Shear- Allowable Allowable Allowabledegrees Shear Tension Shear Tension Qblique

Ratio Ratio Stress, Stress, Stress,ksi ksi ksi

0 0 a 15.00 0 15.0027 0.51 1.95 14.00 7.18 15.7238 0.77 1.30 13.00 9.98 16.4045 1.00 1.00 12.00 12.00 16.9649 1.14 0.88 11.40 13.00 17.3053 1.31 0.77 10.71 14 00 17.6356 1.50 0.66 9.92 15.00 17.9661 1.79 0.56 9.00 16.00 18.3765 2.15 0.46 7.90 17.00 18.7570 2.75 0.36 6.54 18.00 19.1676 4.06 0.25 4.68 19.00 19.5890 a 0 0 20.00 20.00

* "How Much Combined Stress Can a Rivet Take?" by T. R. Higgins andW. H. Munse, Engineering News Record, December 4, 1952.

Q - ý4 in. diam

~Z

Iia

5'

0

St

I

V. SUMMARY OF RESULTS AND CONCLUSIONS

15. Summary of Results

The results of the tests reported here may besummarized briefly as follows:

A. Preliminary Tests(1) The difference in ultimate strengths between

rivets of killed, semi-killed, and rimmed steels sub-jected to identical heating and driving conditionswas small (less than 5 per cent).

(2) Variations in furnace temperatures between1800 F and 1950 F and driving (hand-pneumatic)times between 7 and 30 see had only a small effectupon the ultimate strength of the rivets.

(3) The initial tension in the rivets was equalapproximately to the yield point of the rivets forthe 2-in. grip, the only grip for which these meas-urements were made.

(4) The length of soaking time to which therivets were subjected, before driving, appreciablyaffected the ultimate strength of the rivets.

B. Shear-Tension Tests(5) An increase in grip from 1 in. to 5 in. pro-

duced a reduction in ultimate strength of approxi-mately 8 per cent.

(6) The method of rivet manufacturing (hot-or cold-formed) had little or no effect on the ulti-mate strength of the rivets tested at various shear-tension ratios.

(7) The machine driven rivets (from only onefabricator) appeared to be slightly weaker than thehand-pneumatic driven rivets; however, the heat-ing and soaking conditions for the machine andhand-pneumatic driven rivets were different andmay account for the difference in strength.

(8) The variation in ultimate strength withrivet diameter was generally less than 7 per cent.

(9) The energy absorbing capacity of rivetssubjected to static loads was greatly reduced as theshear-tension ratio was increased.

16. Conclusions

On the basis of the tests reported here it may beconcluded that the ultimate strength of rivets sub-jected to loads ranging from direct tension to directshear can be conveniently expressed in the formof a non-dimensional elliptical interaction curve orin the form of other simple interaction relation-ships. From the elliptical curve, the ultimatestrength, S, of a rivet subjected to a force havingany combination of shear and tensile componentscan be obtained easily by means of the followingrelationship:

S = rwhere

13 o1 + m2

r 1.333< (1.333)2 + m 2

Tensile component of forcem - Shear component of force

and S. = Ultimate strength of rivet in direct shear.

The relationship S = rS, could be easily appliedto design specifications, simply by replacing theultimate shearing strength by the maximum allow-able shear stress.The factor of safety for a rivetsubjected to combined tension and shear would thenbe the same as the factor of safety for a rivet sub-jected to direct shear.

ILL IN 0 I S - CORE · characteristics of the 7 s-in. hand-pneumatic driven rivets is given in Fig....

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