ti no . 70 -2 - missouri · 2 details of test beams 3 comparison of ultimate loads ... ultimate...

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~--..rn:-1SOURI COOPERATIVE HIGHWAY RESEARCH PROGRAM

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REPORT

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Pr0oerty of

MoDOT TRANSPORTATION LIBRARY

/ "STATIC AND FATIGUE

PROPERTIES OF HIGH-STRENGTH BOLT SHEAR CONNECTORS",,

FINAL REPORT

MISSOURI STATE HIGHWAY DEPARTMENT

UNIVERSITY OF MISSOURI-COLUMBIA

BUREAU OF PUBLIC ROADS

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MISSOURI COOPERATIVE HIGHWAY RESEARCH PROGRAM REPORT 70-2

uSTATIC AND FATIGUE PROPERTIES OF

HI GH-STRENGTH BOLT SHEAR CONNECTORSu

FINAL REPORT


UNIVERS1TY OF MISSOURI - COLUMBIA


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"STATIC AND FATIGUE PROPERTIES 0

HIGH-STRENGTH BOLT SHEAR CONNECTOR"

STUDY 68-4 FINAL REPORT

Prepared for


by

LAWRENCE N, DALLAM

DEPARTMENT OF CIVIL ENGINEERING

UNIVERSITY OF MISSOURI

COLUMBIA, MISSOURI

JUNE, 1970

in cooperation with

U,S, DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION


JUN 2 9 1973

--"'&."' ... _.!

The opinions, findings, and conclusions

expressed in this publication are not necessarily

those of the Bureau of Public Roads.

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Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Static Behavior of Connector Positive Moment Region

Pushout Tests Beam Tests

Negative Moment Region Pushout Tests Beam Tests

Fatigue Behavior of Connector

Pushout Tests Continuous Beam Tests

Design Recommendations References

Appendix: Pushout and Beam Notation

2

2

3

5

5

6

7

9

47

48

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LIST OF FIGURES

FIGURE

1 Detai 1 of Push out Specimens . . . . . . 2 Load-Average Slip Curves of 3/4-inch Bolts 3 Details of Composite Beams ..... 4 Slip Distribution Along Beam NFB4B2. 5 Load vs. Deflection for 12 Series . . 6 Load vs. Deflection for 21 Series . 7 Strain Profile at Section 43.5 inches from South End

of NFB4B2 . . . . . . . . . . . . . 8 Force per Shear Connector vs. Slip for NFB4B2 9 Force per Shear Connector vs. Slip for NFB5Bl

10 Force per Shear Connector vs. Slip for NFB6Bl . 11 Force per Shear Connector vs. Slip for LFB6Bl 12 Details of Tension Pushout Specimen 13 Load Versus Slip - N6T4TBla,b 14 Instrumenta t ion - NCB6Bl .... . 15 Instrumentation - NCB6B2 .... . 16 Instrumentation - NCB6B3 . . . 17 Cross Sections at the Negative Supports ... 18 Comparison of Deflections - NCB6Bl and NCB6B2 19 Comparison of Slips - NCB6Bl and NCB6B2 . 20 Overhang Deflection - NCB6B3 . . . 21 Strain Profile - NCB6B3 . . . . 22 Dimensions and Instrumentation of NCB6FBl .. 23 Dimensions and Instrumentation of NCB6FB2 24 Deflection at Load Points . . . . . . 25 Working Strain Profile at Section C ... 26 Slip Distribution at Working Load of NCB6FBl 27 Load-Slip at a Typical Connector 28 Applied Load vs. Negative Moment 29 Comparative Cracking Patterns .

PAGE

12 13 14 15 16 17

18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

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LIST OF TABLES

TABLE

1 Canpression Pushout Test Results

2 Details of Test Beams

3 Comparison of Ultimate Loads

4 Critical Load of Shear Connectors

5 Tension Pushout Test Results

6 Results of Beam Tests

7 Fatigue Results of Pushout Tests

PAGE

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42

43

43

44

45

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11 STATIC AND FATIGUE PROPERTIES OF HIGH-STRENGTH

BOLT SHEAR CONNECTORS 11

PREFACE

An experimental investigation, cosponsored by the State Highway

Commission of Missouri and the Bureau of Public Roads, was undertaken

at the University of Missouri-Columbia campus to determine the static

and fatigue properties of high-strength bolts when used as shear con

nectors in concrete-on-steel composite beams.

The investigation was performed in four phases over a four-year

period. The first phase consisted of the testing of a series of push

out specimens to determine the feasibility (from a strength point-of

view) of using bolts as shear connectors (1). From the results of these

tests, six full-scale, simply-supported beams were tested to study the

behavior of bolts in the positive-moment region of composite beams

subjected to static loads (2). The third phase was designed to study

the behavior of the connector in the negative-moment region of composite

beams (3). Three full-scale overhanging beams were tested under static

loading, two with connectors and one without, and a series of tension

pushout specimens were tested. The fourth phase was designed to study

the behavior of the bolt connector under fatigue and dynamic loading (4).

A series of pushout specimens and two two-span continuous composite

beams were tested with repeated loading. The beams were also subjected

to a final static loading.

An explanation of the notation used to identify the pushout and

beam specimens mentioned in this report is given in the Appendix.

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STATIC BEHAVIOR OF CONNECTOR

The behavior of the connector under static loading depends upon

whether the slab is in compression or tension. The discussion will be

limited to A325 high-strength bolts embedded about four inches in a

six-inch slab.

Positive Moment Region

Pushout Tests - In the course of the study, eighteen pushout tests

were perfonned with 3/4-inch diameter bolts. The test specimens (Figure

1) were similar except for the amount of reinforcing steel in the slab.

In specimens 1 through 8 (Table 1) the longitudinal steel was 2 - #3

bars; in specimens 9 through 16 it was 3 - #5 bars and in specimens 17

and 18 there were two layers (one top and one bottom) of 3 - #5 bars.

The test results are shown in Table 1 and it is seen that the ultimate

load for specimens 17 and 18 is considerably higher (about 50%) than

the other specimens. The presence of the additional longitudinal and

transverse reinforcing steel in the bottom of the slab improves the

stress condition in the concrete in the neighborhood of the bolts. The

ultimate load for specimens 1 through 16 was limited by the strength of

the concrete, but by adding steel in the bottom of the slab to better

approximate the conditions in an actual composite girder, the ultimate

load for specimens 17 and 18 was limited by the shearing strength of

the bolts. It is also of interest to note that the flanges of specimen

17 were oiled to prevent the development of any bond between the steel

and concrete.

Typical load-slip curves are shown in Figure 2 and it is apparent

that there is practically zero slip in the connection until friction is

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3

overcome.

Beam Tests - The details of the beams are shown in Figure 3 and

Table 2. The purpose of the tests was to: (A) compare elementary beam

theory with experimental behavior, (B) compare the behavior of the

bolt as a shear connector in a beam with its behavior in the pushout

specimen, and (C) to compare ultimate strength theory with experimental

behavior.

(A) Elementary beam theory assumes no slip between the concrete

slab and steel beam. Figure 4 shows the distribution of measured slip

along beam NFB4B2 and is typical of the six beams tested. It is noted

that there was essentially zero slip throughout the elastic range of

the beam. Since there was practically no slip in the elastic range,

the predicted instantaneous deflection and strain values based upon

complete interaction should have compared very favorably with the

measured values and Figures 5,6 and 7 show this to be true. The

variations in Figure 5 are due to the number of connectors in each

beam. Beams NFB4Bl and NFB5Bl were designed to fail in the connector

and NFB4B2 was not.

(B) An important aspect of this phase of the testing program was

to measure the force and slip in a connector in the beam and compare

this relationship with that of a connector in a pushout test. Figures

8, 9, 10 and 11 show these comparisons. Because the connection is

the friction-type, it is not surprising that the behavior in the

working range (before friction is overcome) in the beam is almost

exactly the same as that in the pushout. The load-slip behavior

beyond the critical load also compares favorably with that of the pushout,

especially for the 1/2 and 5/8-inch diameter bolts in Figures 8 and 9.

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The 3/4-inch diameter bolts (Figures 10 and 11) appear to be stronger in

the beam than in the pushout, but, as previously discussed, this is

because the beams had two layers of reinforcing steel in the slab

(top and bottom) whereas the pushouts only had one layer (top). The

measured ultimate force in the connector was about 50 kips in the beam

test (Figures 10 and 11) which compares very favorably with the ultimate

load of 50.0 and 52.2 kips obtained in the pushout specimens that had

two layers of reinforcing steel in their slabs.

(C) The composite beams were analyzed using the usual ultimate

strength theory (5) for beams with adequate connectors or a modified

version for beams with inadequate connectors (6), whichever was applic

able. The calculated and measured ultimate loads are listed in Table 3

where it is seen that in the first three beams (1/2-inch or 5/8-inch

diameter bolts) there is very good agreement between the calculated and

measured values. However, in the last three beams (3/4-inch diameter

bolts) the measured load is much higher than the calculated, because

the values for the ultimate strength of the bolts were obtained from

the pushout tests which did not have the same percentage of reinforcing

steel in the slab as did the beam (seep. 3). If an ultimate strength

of 50 kips per bolt is used, then the values under 11 adequate connection 11

would be applicable and they compare favorably with the measured values.

Table 4 further demonstrates the accuracy of both the elementary

beam theory and pushout tests in predicting the behavior of composite

beams when bolts are used as shear connectors. The calculated (predicted)

load at which friction is overcome is based upon pushout test results

and e.l ementary beam theory (complete interaction and a transformed

section). It is seen that the predicted load is quite close to the

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measured load.

Negative Moment Region

5

Pushout Tests - Eight pushout specimens were prepared such that

the slab would be in tension (Figure 12). The results of the tests

are shown in Table 5 and compare favorably with the compression push

out test results (Table 1). The load-slip relationship (see, for

example, Figure 13) is also similar to that of the compression push

out specimen.

Beam Tests - Three composite overhanging beams were tested to

detennine the behavior of the composite section in the negative

moment region. The test beam details are shown in Figures 14, 15, 16

and 17. Beam NCB6Bl was designed as composite in the negative moment

region with an inadequate amount of reinforcing steel to develop the

ultimate possible moment capacity of the section (that is, to fully

yield the steel beam section). Beam NCB6B2 was similar to NCB6Bl

except no shear connectors were placed in the negative moment region.

Beam NCB6B3 was designed with sufficient reinforcing steel to fully

yield the steel beam section (theoretically).

It is of particular interest to compare the behavior of beams

1 and 2 (with and without shear connectors in the negative moment region)

as to the degree of composite action developed. From a comparison of

deflections (Figure 18) at the working load of NCB6Bl (about 32k), the

beam without connectors experienced 28% more deflection than the beam

with connectors. A more graphic picture of the degree of composite

action in each beam is shown in Figure 19, where the slip at the inter

face of the slab and steel beam is plotted at a point eight inches to

the right of the support for each beam. It is clearly apparent that


6

the shear connectors were performing as indicated by the tension push

out tests and almost full composite action is present in the working

range of the beam.

This observation holds true for the third beam tested as seen in

Figures 20 and 21, which show the deflection curve and strain profile

(eight inches to the right of the support).

A comparision of predicted and measured values of working, first

yield and ultimate load is given in Table 6. The agreement is very

good, considering that the predicted or theoretical values are based

upon a fully cracked slab and therefore neglect the tension in the

slab between cracks . Beam NCB6B3 did not quite attain the predicted

ultimate load because of premature failure by buckling of the bottom

flange of the steel beam section.

FATIGUE BEHAVIOR OF CONNECTOR

Pushout Tests Ten pushout specimens (Figure 1) were subjected to

repeated loading in order to determine the fatigue life of 3/4-inch

diameter high-strength bolts. The main variables were the range of

shear stress in the bolts and the strength of the concrete. Of the

ten specimens tested, two were damaged by inadvertent overloading

and the results of the other eight are shown in Table 7. The following

observations can be made from these tests:

(1) the concrete strength was not a factor in the fatigue life

(2) the high-strength pretensioned bolt did not fail at load

ranges below the critical load of the bolt (friction not overcome) and

applied ten million times.


7

In only one specimen (N6F4TB3) was a fatigue failure obtained and

that by loading considerably beyond the critical load. This specimen

had also been subjected to ten million cycles in the working range and

700,000 cycles at a range of stress of 40 ksi before the final failure

range of stress (54.6 ksi) was applied .120,000 cycles.

Specimen N6F4TB7 was loaded to its critical load (22.98 kips)

two million times without failure.

Continuous Beam Tests Two, full-scale, two-span-continuous beams

were tested under fatigue and static loading. Both beams had shear

connectors in the positive moment regions but beam NCB6FB1 (Figure 22)

did not have connectors in the negative moment region whereas beam

NCB6FB2 (Figure 23) did.

Each beam was loaded to its approximate working load two million

times with no apparent distress in the connection or in the tension

flange of the steel beam over the center support of NCB6FB2 (there

were holes in the tension flange). The reason for this absence of

distress in the connection and in the tension flange with holes is

that the shear force at the interface was less than the critical load

of the bolts and therefore friction was not overcome and there was

practically no slip. It should be noted that the number and spacing

of the connectors was detennined using an allowable value of 20 kips

per bolt and a maximum spacing of 24 inches. This means that there

was essentially no factor of safety against slip in the test beams.

Upon conclusion of the fatigue loading, each beam was loaded

statically to attain the anticipated ultimate negative moment at the

center support and to compare the behavior of continuous composite

beams with and without shear connectors in the negative moment region.


8

The behavior will be discussed in tenns of deflection, strain, slip,

distribution of bending moment and degree of cracking.

(1) Deflection - The midspan deflection of beam #1 (without

connectors) was 11% greater than beam #2 (with connectors) in the working

range of the beams (Figure 24).

(2) Strain - A comparison of the strain at a section 35 inches

from the center support is shown in Figure 25. The strain in beam #1

is about 20% greater than that of beam #2, in the working range.

(3) Slip - Figure 26 very clearly shows the great difference in

slip in the two beams and the effectiveness of the shear connectors

in beam #2. It is also of interest to compare the load-slip behavior

of the first pair of connectors in the positive moment region of beam

#1 with those at the same location in beam #2 (Figure 27). It is seen

that the connectors in beam #1 (no connectors in negative moment region)

must carry much more force than those in beam #2.

(4) Distribution of Bending Moment - The placement of shear con

nectors in the negative moment region of a continuous beam will in

crease the moment of inertia of the section in that region and therefore

the bending moment should also increase. Figure 28 shows that there

was an increase in moment in beam #2 (compared to beam #1) of about

7% at its working load and also shows that the moment in beam #1 is

slightly larger than the theoretical moment, due to the existence of

some composite action.

(5) Degree of Cracking - The effect of placing high-strength bolt

shear connectors in the negative moment region on the cracking behavior

of the slab was to reduce the number of cracks formed but to increase

their width (Figure 29). That is,to design compositely in the negative


9

moment region wil l produce fewer but wider cracks. The maximum crack

width at the working load of beam #2 was .4mm (.016 inches), which is

not serious.

DESIGN RECOMMENDATIONS

A. Shear - From the results of this testing program, it is

evident that fatigue consideration is not the governing factor in the

design of the connection between the concrete slab and the steel beam.

It is also evident that elementary beam theory using the transformed

section is quite accurate in predicting the behavior of the composite

girder. It is therefore recommended that the horizontal shear to be

transferred by the shear connectors be computed by the formula

s = YQ I

whose terms are identical to those in section 1.7. 101 of the 1965

AASHO Standard Specifications for Highway Bridges.

It is recommended that the allowable design load "Z" of a 3/4-

inch diameter A325 high-strength pretensioned bolt embedded a minimum

of four inches in a concrete slab whose 28-day compressive cylinder

strength is at least 4000 psi, be as follows:

Z = 12.00 kips per bolt

and this value be used in both the positive and negative moment regions.

This value (Z = 12.0) was determined by applying a factor of .55

to the average critical load (22 kips) determined from pushout tests.

The application of the factor .55 results in the same factor of safety

against significant slip in the connection as is present in the beam

against yielding (.55F ). It also insures that a sufficient number of y


10

connectors would be present to develop the ultimate moment capacity

{positive or negative) of the composite section without failure in the

connection.

It is further recommended that additional connectors be placed in

girders designed non-compositely in the negative moment region. The

number of additional connectors required at points of contraflexure

when reinforcement steel embedded in the concrete is not used in

computing complete section properties for negative moments could be

computed by the formula: A f

N =~ C 2

where N = the number of additional connectors at the point of C

contra flexure.

As= the area of longitudinal reinforcement steel over an interior support contained within the effective flange width of the concrete slab.

fs = the allowable design stress of the slab reinforcement.

Z = the allowable design load of the high-strength bolt connector.

These additional connectors should be placed at the point of dead load

contraflexure, centered about it, and spaced longitudinally at about

six inches.

B. Spacing - The required spacing of the bolts is determined by

dividing the resistance of all bolts at one transverse girder cross

section (~Z) by the horizontal shear S per linear inch, The minimum

spacing should be about six inches and the maximum 24 inches.

The minimum transverse spacing of bolts shall be four inches and

where slabs are haunched, the distance from the edge of the bolt to

the beginning of the haunch taper at the elevation of the steel beam

flange shall be not less than the embedded length of the bolt.

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11

C. Installation - The preparation of the holes and the tensioning

of the bolts shall conform with the current specifications (7) for

structural joints fastened by high-strength bolts. It is recormnended

that the bolts be tightened only after the concrete has attained a

minimum of 75% of its 28-day cylinder compressive strength.

D. Fatigue Stress in Steel Beam - It is recommended that the

allowable fatigue stress in the flange of the steel beam be determined

according to the current AASHO Specifications for 11 Base Metal adjacent

to friction type fastener 11•

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r C

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p Fo

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en

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re

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ctor

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Fig

ure

10

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r S

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nect

or V

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for

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re

11

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r Sh

ear

Con

nect

or V

s. S

lip

for

LFB6

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0.21

0.

24

N

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STRAIN GAGE

t

--- SLIP DIALS _ .. __ .... _

A

I 5 1/3 11

---r-4- - - -t-r - -

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t

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411

# 4 BARS • 8"

24 11

311

# 7 BARS--....L.......-. •--------' 411

SECTION A-A

Figure 12 Details of Tension Pushout Specimen

23


4111111

rd ,-co I-<d'" I-

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14

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15

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4 I.S.@ 6 in. centers

4 H.S. ·

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centers # 4 H.S.

6 in.

Figure 17 Cross Sections at the Negative Supports

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re

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22

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and

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w

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men

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Fig

ure

24

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at L

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nts

•

NC

B6

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r------------------------------

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Fig

ure

26

Sli

p D

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at W

orki

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Load

of

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Fig

ure

27

Loa

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lip

at a

Typ

ical

C

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w

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Fig

ure

28

App

lied

Load

vs

N

egat

ive

Mom

ent

l.,J

I.O

----

--M

ax.

W=

.20

mm

N~

Pw

=7

0K

Ma

x.

W=

.40

mm

Pw

=IO

OK

----

----

----

Ma

x. W

= .3

0m

m

P

= 1

20

k

y

NC

B6

FB

I

Ma

x.W

=.5

8m

m

----

----

. .

. .

----

----

Py=

15

0K

NC

B6

FB

2

Figu

re 2

9 C

ompa

rativ

e C

rack

ing

Pat

tern

s

Ma

x. W

=.4

6m

m

-M--

----

p =

2Q

QK

Ma

x.W

= 1

.0 m

m

----

- . . --

--- p

=2Q

QK

.

.i:,

.

0

I I I I I I I I I I I I I I

I I I

41

TABLE 1

COMPRESSION PUSHOUT TEST RESULTS

f' No. of Layers of C * Critical Ultimate Failure Longitudinal Rein-

Specimen psi Load,Kips Load,Kips Mode forcement in Slab l N684TB1 8440 27.1 38.0 Concrete 1 2 N6A4TB2 8440 27.0 37.4 II 1 3 N6A4TB3 8440 24.0 34.7 II 1 4 N6A4TB4 8440 26.3 36.7 II 1 5 N684TB5 3720 17.8 32.6 II 1 6 N6B4TB6 3720 21. 2 31. l II 1 7 N6B4TB7 7130 21.0 37.2 II 1 8 N6B4TB8 7130 18.5 34.9 II 1 9 N6F4TB1 4121 32.5 II 1

10 N6F4TB2 4436 31.8 II 1 11 N6F4TB4 6690 18.of 32.6 II 1 12 N6F4TB5 7061 17.5f 34.0 II 1 13 N6F4TB6 6955 23.0 II l 14 N6F4TB7 8217 21. 1 35.6 II 1 15 N6F4TB8 8380 20.5f 34.2 II 1 16 N6F4TB9 8310 19.5f 33.7 II l 17 N6F4TBla 7026 20.6f 50.0 Bolts 2 18 N6F4TBlb 7522 28.4 52.2 Bolts 2

Average 22.0 Note: All bolts 3/4 11 in diameter, embedded 411 in the slab and conform to

ASTM A325-61T.

* Load at which friction is overcome f Determined after fatigue loading

--

Sp

ecim

en

(B

eam

an

d

Pu

sho

ut)

NF

B4

Bl

N4B

4TB

5

NF

B4B

2 N

4B4T

B6

N4B

4TB

7 N

4B4T

B8

NF

B5B

l N

5B4T

B5

NS

B4T

B6

NS

B4T

B7

NF

B6B

l N

6B4T

B5

N6B

4TB

6

NF

B6B

2 N

6B4T

B7

N6B

3TB

8

LF

B6

Bl

L6B

4TB

1 L

6B4T

B2

Seri

es

12

12

12

21

21

21

--

----

----

Age

at

Test

day

s

90

89

77

1

87

1

90

3

5

13

9

21

1

21

2

21

3

28

3

1

17

1

59

5

8

13

8

56

5

2

52

Tab

le

2

Deta

ils

of

Test

Bea

ms

Dia

mete

r o

f B

olt

s

inch

es

1/2

1/2

5/8

3/4

3/4

3/4

Nu

mb

er

of

Bo

lts

12

28

12

28

28

28

Heig

ht

of

Bo

lts

inch

es

4-1

/2

4 4-1

/2

4-1

/2

4 4

Sp

acin

g o

f B

olt

s

on

H

alf

o

f B

eam

2@20

"

6@9"

2@20

"

3@

16

",

2@

24

",

1@26

"

3@

16

",

2@

24

",

1@26

"

3@16

II

f 2@

24 II

f

1@26

II

Dis

tan

ce

fro

m L

ast

Bo

lts

to

cL

inch

es

70

63

70

14

14

14

~

N

I I

I I

I

I

I I

I

Specimen

NFB4Bl NFB4B2 NFB5Bl NFB6B 1 NFB6B2 LFB6Bl

TABLE 3

Comparison of Ultimate Loads

Predicted Ultimate Load

Adequate Connection

kips per jack

51. 7 53.5 53.9 40. 1 43.3 43.7

Furnished Connection

kips per jack

34.8 49.6 42.8 37. l* 39.9* 38.3*

43

Measured Ultimate

Load kips per

jack

34.9 50.2 41. 6 42.0 47.0 45.3

* Based upon an ultimate load of 33 kips per bolt (see p.4)

Specimen

NFB4Bl NFB4B2 NFB5Bl NFB6B 1

NFB6B2

LFB6Bl

Critical

TABLE 4

Load of Shear Connectors*

Measured Load per Jack

~

17.4 34.1 24.6 26.0 26.0 29.7

* Load on beam when friction is overcome in connection

Calculated Load per Jack

kips

16. 5 34.9 24.2 27.0 25.3 31. 1


Specimen

N6T4TB1a N6T4TB1b

N6T4TB2a N6T4TB2b

N6T4TB3a N6T4TB3b N6T4TB4a N6T4TB4b

TABLE 5

TENSION PUSHOUT TEST RESULTS

f' C

Critical Load psi Kips

7953 23.8 7953 19. 7 8292 19.0 8292 19.3

6523 17. 4 6523 20.8 6700 22.6 7168 22.3

Average 20.6

44

Ultimate Load Kips

34.4 37.3

38.2 30.2

27.5 32.7 30.9 31. 5 32.8

I I

45

I TABLE 6

RESULTS OF BEAM TESTS

I NCB6Bl Theoreti ca 1 Experimental

I Working Load 31.6 (kips) 33.0 (kips)

I Yielding Load 59.8 52.5

Ultimate Load 80.8 87.3

I I NCB6B2 Theoretical Experimental

I Working Load 27.5 27.3

Yielding Load 53.9 52. 1

I Ultimate Load 66.2 84.7

I I

NCB6B3 Theoreti ca 1 Experimenta 1

I Working Load 36.7 39. l

I Yielding Load 65.5 67.3

Ultimate Load 103.5 l 01. 3

I I I I I

11 I I I I I I I I I I I I I I I I I I

TABLE 7

FATIGUE RESULTS OF PUSHOUT TESTS

f' Load Range C Min Max. S* Specimen

psi K/Bo lt K/Bolt Ksi

N6F4TB1 4121 .885 5.30 10.0 .885 14. 14 30.0

N6F4TB3 4253 .885 18.58 40.0 .885 25.00 54.6

N6F4TB4 6690 4.425 17.68 30.0 N6F4TB5 7061 .885 18.58 40.0 N6F4TB7 8217 .885 22.98 50.0 N6F4TB8 8380 .885 15.30 32.6 N6F4TB9 8310 .885 15.30 32.6 N6F4TB1 a 7026 .885 15. 30 32.6

* Range of shear stress in bolt

46

No. of Cycles Failure

X l 06

5.00 - - - - ~ -- - · H

10.00

0.70

0. 12 Bolts 10.00 2.40 2.00 2.00 2.00

2.00

I I I I I I

I I I I I I I I

I I I

REFERENCES

1. Dallam, L. N., "Pushout Tests With High-Strength Bolt Shear Connectors", Missouri Cooperative Highway Research Program Report 68-7, Engineering Experiment Station, University of Missouri-Columbia, 1968.

47

2. Dallam, L.N., and Harpster, J. L., "Composite Beam Tests With High-Strength Bolt Shear Connectors", Missouri Cooperative Highway Research Program Report 68-3. Engineering Experiment Station, University of Missouri-Columbia, 1968.

3. Dallam, L. N. and Gaudini, P.B., "Static Behavior in the Negative-Moment Region of Composite Beams Using Bolts as Shear Connectors", Missouri Cooperative Highway Research Program Report 69-3, Engineering Experiment Station, University of Missouri-Columbia, 1969.

4. Dallam, L. N., and Guran, R., "Static and Fatigue Behavior of Continuous-Composite Beams with High-Strength Bolts as Shear Connectors'', Missouri Cooperative Highway Research Program Report 70-1, Engineering Experiment Station, University of Missouri-Columbia, 1970.

5. Slutter, R. G. and Driscoll, G. C., Jr., "Flexural Strength of Steel and Concrete Composite Beams", Journal Structural Division, ASCE, Vol. 91, No. ST2, April 1965, p.84.

6. Ibid. p. 91

7. 11 Speci fi cati ans for Structural Joints Using ASTM A325, or A490 Bolts", American Institute of Steel Construction, Research Council on Riveted and Bolted Structural Joints of the Engineering Foundation, New York, 1964.


APPENDIX

PUSHOUT NOTATION

There were three types of pushout specimens tested in this investi

gation: compression, tension and fatigue. In each type, the first

letter indicates the kind of concrete used; N for normal weight or

L for lightweight. The second character is a number which denotes

the diameter of the bolt in eighths of an inch. The third character

distinguishes between the three types of specimens; B denotes the

compression specimen, T the tension specimen and F the fatigue

specimen. The next character is a number indicating how many bolts

were on the specimen. The next two letters, TB, stand for a tensioned

bolt, that is, a pre-tensioned high strength bolt, to differentiate

the specimen from others using a different type of connector. The

last character(s) distinguish between specimens with otherwise

identical notation.

For example, an N6F4TB2 pushout specimen had slabs made of

normal weight concrete and were connected to the steel beam stub

by four 6/8-inch diameter high strength pre-tensioned bolts. The

specimen was tested under fatigue loading and was the second of

a series.

BEAM NOTATION

There were three types of full-scale beam specimens: simple

span, overhang and two-span continuous. Each was designed to test

the shear connection with a particular type of loading: that which

produces static positive curvature, static negative curvature and

I

I I

I I I I I I I I I

I I

fatigue and dynamic positive and negative curvatures. The adopted

notation reflects the type of concrete used in the slab, the type of

beam, the diameter of the shear connector, the type of loading and

the type of connector.

Simple Span Series - NFB5Bl - The first letter denotes the type of

concrete (normal weight, N, or lightweight, L); the next two, FB,

indicate that the specimen is a full-scale simply supported beam.

The next character is a number specifying the diameter, in eighths of

an inch, of the shear connectors. The next letter, B, indicates that

the connectors are bolts and the final character is a number which

distinguishes between beams with otherwise identical notation. The

loading is, in all cases, static.

Overhang Series - NCB6Bl - The notation is identical to the simple span

beams, except for the second letter, C, which indicates that the beam

is continuous over one support.

Two-Span Continuous Series - NCB6f.Bl - The notation has the same meaning

as the other beam series, except the letter F was inserted to indicate

that the loading was repeated and dynamic (fatigue) in nature and that

the beams were two-span continuous.

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ti no . 70 -2 - missouri · 2 details of test beams 3 comparison of ultimate loads ... ultimate...

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