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Beam-to-Column Connect~ons

HIGHLIGHTS OF TESTS OF STEELBEAM-TO-COLUMN BOLTED CONNECTIONS

(C6, C7, C8,C9)

by'W. F. Chen

K.F. Standig:G. P. Rentschler

This work has been carried. out as part of an investigationsponsored jointly 'by the American Iron and Steel Institute and theWelding Research.Council.

f~F~J'rz Ef\IGiNEEF~ Ij\~(::1

T()f?Y

Department of Civil Engi~eering

Fritz'Engineering Laboratory,Lehigh University,

Bethlehem, Pennsylvania

Oc~ober 1974

Fritz Engineer~ng Labor<atory Report No. 333.29

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333.29333 (AISI 137)18 Oct 74

Highlights of Lehigh Connection Tests(Cp, C7, C8, C9)

The test program consisting of twelve full-size mom~nt-

resisting beam-to-column connections conducted at Fritz Engineering

Laboratory, Lehigh University has recently been completed. The overall

objective of this study is to d~velop 4esign procedures for safe, effi-

cient, and economical ,beam-to-column' connections. Primary attention

'wa~ focused upon the strength (plastic limit load), deformation

'capacity, and over-~11,stiffness of" the connections.

The tests result 'h~ghlights' presented herein are of 'the four,

bolted s'pecimens tested in the twelve specimen program. They are

con~ections C6, C7, C8.and C9_ The experimental and refere~ce lo~ds

along with a brief description of the joint and the failure mode are

given in Table 1.

C6 and C7

Connections C6 and C7 are shown respectively in Fig. 1 and

Fig. 2.' Both connections were designed u~ing A572 Grade 55 steel with

a WIOx60 column section and a W14x74 beam section.

Connection C6 is ;flange-bolted (8':'1"c.p A490 bolts in, l-1/~6~'

round holes in each flange) utili..zing 1-l/8"x~O", f~~nge connection

"plates with the beam shear carried ·by a stiffened seat plate. 'Connec-

tion C7 has the same bolting co~figuration, ~olt diameter, and hol~

sizes in ~he flange asC6. The bolted parts of both specimens were

'designed as, bearing. type connections. However, in C7,_ the shear is

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carried by means of a shear plate welded to the column flange and

bolted to the beam 'tV'eb by 3-1"tp A490 bol~s in 1-l/16~' round holes.

-2

The load versus deflection curves for C6 and C7 are give~

in Fig. 3. Also sllown on the figure is a p lot of CIO which is "the

control (fully welded) specimen using the same· beam and column sections

as C6 and C7. On this plot, as well as the plot of C8 and C9, the

'effects 'of slip are averaged b'y not plotting any of the horizontal

slip plateaus. Note_that th~ load-deflection plots for both C6 and

C7 have three -distinct phases (slopes).

Photographs describing the failur~ of connection Co are shown

in Fig. 4 through Fig-. 7. Fig.ure' 4 shows an overall view of: C6 a·t

failure depicting the extensive yielding in the beam web up to the end

of the moment plates. Failure of this- connect1on occurred at a load

-of 478.5 kips when the eight bolts conne~tjng the tension flange

sheared off simultaneous-ly.- Figu~e 5 pres~nts a closer look at the

beam on which the eight bolts failed.

Shown in Fig'. ·6 is a view of the column panel zone adjacent

to the beam tensio,D. flanges ,.: Figure 7 show·s the s·hear 'failure: of fo.ur

of the 'bolts and the extensive ~eformation of the bolts at failure.

Photographs detailing the failure of conne~tion C7 are shown

in Fig. 8 through Fig. 12". Figure 8 shows an overall view of C7 at,

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failure ·ag~in depicting the extensive yielding in the beam web (Fig. 9)

up to the end of the moment connection plates. Failure'of this connec­

tion was due to the failure of five bolts in one of the tensi~n flange

,connections. Two outside bolts in this flange failed at a load of 361

kips due to the prying action as shown in Fig. 10. Upon further loading

three more bolts failed at the maximum load of 450 kips.

Shown in Fig. 11 is a view of the panel. zon~ sho~ving yielding

and '8 view of the beam web connection plate and the re'lative rotation

of the beam web and the web 'connection plate. Figure 12 presents a

view of the 'five bolts which failed.

C8 and C9

'Connections a8 and C9 are shown respectively in Fig. 13 and

Fig. 14. Both connections were designed using ASTM A572 Grade 55 steel

,with a W14x136 column section and a: W2'4x~1 beam section.

Connection C8 is a flange..bolted (14-l"q; A490 bolts in l1z;"tp

. holes in each flange) and web~bolted (7-3/4t1 Cfj ,.A325 bolts in slotted

holea). The flange ~onnections were designed as frict~on connections

using aliowable bolt shearing stress values below those of a bearing

type joint. The flange ,connection'p~ates are 3/4 t1x:ll". The web con~

nection.was designed as a bearing joint. u~~ng A325 bolts in slotted

holes perpendicular to the direction of loading. Connection C9 is

identical to C8 except the design'of the bolted flange connection was

b.ased on treating the "joint as a bearing connection. This l..ed~ to a

'flange connection r~quiring 6-1"cp.A490 bolts in 1-1/16" round holes

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and flange connection plates of 3/4I x11".

The load versus deflection curves for C8 and C9 are given

in Fig. 15. Also shown on the'figure is a plot of ell which is the

control (fully welded) specimen using the same beam and column sizes

as C8 and C9.

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Photographs detailing, the failure of connection e8,are shown

in Fig. 16 through Fig. 19. The maximum load reached on this connection

was 516 kips. After reaching this level, the load dropped off due to

column web buckling and the test was terminated for 'safety reasons.

Figu~e 16 shows an overall view of C8 at the termination of test.

Shown in Fig. 17- is a view of one of the beams where it is

connected to the column. On this view the· appearance of slip on the

tension flange (top) can be detected, by the relative mqvement of the

vertical lines. Slip ~n the compression-flange (bottom) was much less.

Figure 18 shows the extensive yieiding which occurred in the column

panel zone and Fig. 19 shows the extent of the ~uckling of the column

web in the compression'region.

Photographs showing ~he failure of connection C9 are given,

in Fig. 20 through Fig. 22. The maximum load 'on this connection was

402 kips. - Failure occurred when ·the six bolts on one of the tension

flange connections and one of the web bolts sheared off simultaneously.

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This can b~ seen clearly in Fig. 22.

Shown in Fig. 20 is an overall view of the connection at

-failure. Figure 21 presents a closer view of the column panel zone

and beam ends showing-the yield pattern.

-5

333.29

TABLE 1 TEST RESULTS OF CONNECTIONS

Joint Failure Bxperirnental Referencep p

Test m m-Description Mode P P P P Pm p pr p pr

C6 Flange-bolted Shearing £ai1- 478.5 322 270 1.49 1.77(bearing) with ure of eightseat(WlOx60 col bolts on one~~4x74 brn.) tension flange

connection

. C7 Flange-bolted Failure of five 450 322 270 1.40 1.67(bearing) web- bolts in ·onebolted(WlOx60 tension flangecol. W14x74 bm) connection.

C8 Flange-bolted . Buckling of 516 315 199 1.63 2.59(friction) web- column webbolted(W14xl36.col. W24x6l bm)

C9 Flange-bolted Shear failure 402 315 199 1.28 2.02(bearing) web- of six ,bolts onbolted (W14x136 one of the ten-col. W.24x61 bm) sien flange con

nections

.Symbols

P = maximum load of connection under te~tm

= plaitic limit load-.pp

p. =pr plastic limit load assuming the area- of beam web is ~ero

Section. 8-8 -

5~G 4

IYalix fOux 15 3/811

MO,ment Plate(Fy =55ksi)

Stiffener Plate

lUx 5 11 x II II (A36)

CornerClipped

Elevation

, WIOx60 WI4 x 74(Fy=55k:j)-u--I-- {_Fy=55ksi)

Sym.

Typ.

A

lUx 4 11 x 8~8"

Stiffener fP.. (Fy=55ksi)

IIIY2- Clearance

Sym.

3/ II II 12~''8 X I xBacking Strip (A3"6)

8-1 11 ¢ A490-X Bolts

1'/1611

Round Holes

Section A--A

Fig. 1 Connection·C6

'Scale:

I Io 5 lOin.

II II I 'I II II/2 X 5i'4 X9'2

Shear It (Fy=55ksi)

8~ I"<P A490-X Bolts

in l'/IGII'Round Holes

I Ye" xIOux15 3/811

Moment Plote(Fy =55ksi)II",3 -I_ 't' A490.-X Bolts

in IYIGII Round Holes

WI4x74WIOx60 3 11 (Fy=55ksi)

--+-f-(Fy=55ksi)-+-lil1-~~oI-l--I----+------

Sym.

A

Elevation

. III X 4 ~I X 8 7/8 "

Stiffener It(Fy=55ksi)

I II .:t2 Clearance

Sy~..

3/811 X oJ ,t"x 12"

Backing 'Strip ( A36)

Section A-AScale:

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Fig. 2 Connection-C7

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Fig. 4 Overall View of C6

Fig. 5 View of C6 Beam

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Fig. 6 Tension Panel, Zone of C6

Fig. 7 Sheared Bolts of Connection C6

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Fig. 8 Overall View of C7

Fig. 9 View of C7 Beam

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Fig. 10 Prying Action of C7 Flange Bolts

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Fig. 11 Panel Zone of Connection C7

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Fig. 12 Bolts at'Failure of C7

Sym.

5 IJ II I"riG x2 x 20Y2 ..

. IIPlate With 13/16,

Round Holes(A36)

WI4xl36

( Fy= 55 ksi) .

14 -III ¢ A490- F Bolts

in IY411

Round Holes

II

3/8 StripShims

7- 3/411¢A325-X Bons

16,LJ~::::;::.:;..r--~ in Slotted Holes

.3@311

=911

-- W24x61 -----~~Cf.

3@3H--_9u (F:y=55ksi) ~ II

d=23 oJ/4

'2 II ,II I IIvIe x5 1'4 X 20 V2

Shear It (Fy=55 ksi)

Elevation.

II rF-------- ,-==--=-~-;::.=:::.=-

:IL-$--" -$-_-$- -$-_-$- -$- -$- J 3~2l1Gage

II r-$-- -$~-$---$--~ -$---$-- .1,LL----- - - - - -,'-'-' ---10----------1----:---- ----_..--- .

Sym.

. Plan View

13" I U I"~16 xll V4 x24V2 -

Moment Plate

( Fy.=50 ksi)

Scale:I I ,

o 5' 'lOin.

Fig. 13 Connection'C8

Sym.

5 II II ":t16 X 2 X 20V2Plate 'with 13/16Round Holes

'(A 36)

WI4x 136( Fy=55 ksi)

Elevation ·

II,/..6-1 \f' A490-X Boltsin IYls" Round Holes

W24x61<Fy= 55ksi)

:3 II ' I II ',". 1'8 X 5Y'4'X 20/2Shear Ie. (Fy=55ksi)

3@ 3 11 =9 11

-_3/allxllf x 13 u

Backing Strip (A36)

( Typ.)

7- 3/411 cP A325-X Bolts

in ,Slotted Holes

13 II 31 If I"~6 )t 10 '4. X 12 V2

Mome'nt Plate

(Fy=50ksi)

3/8 " Strip Shims

Plan View

Sym.

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Scale:,

I Io 5 10 in.

Fig. 14 Connection,C9

'333.29

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Fig. 16 Overall View of C8

Fig. 17 View of C8 Beam

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Fig. 18 Panel Zone of C8

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Fig •. 19 View Showing Buckling-of C8 Column Web

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Fig. 20 Overall View of C9

Fig. 21 Panel Zone of Connection C9

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,F,-ig., 22 - ,View of .C9 Beam a-t Connection