Flange Plate Moment Connection

8/11/2019 Flange Plate Moment Connection

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Moment ConnectionMoment Connection Bolted Flange PlateBolted Flange Plate

Design a moment connection using a bolted

flange-plate

Connect a W18x50 beam to the flange of a

W14x99 column

Use 50 ksi wide-flanges and 36 ksi plates

-

1

45.0 kips 250 ft-kipsu uR M= =


Connection geometry

2


2/14


Shapes

W18x50

W14x99

318.0 in. 7.50 in. 101 in.

0.355 in. 0.570 in.

f x

w f

d b Z

t t

= = =

= =

3

. n. . n. . n.

0.485 in. 0.780 in. 10 in.

f des

w ft t T

= = =

= = =


Proportion of members hole reductions

Where (A992, A36)

then

u fn t y fgF A Y F A

Bolt Limit StateWhen the clear end distance or the clear bolt spacing isgreater than or equal to 2 bolt diameters, bearing strength

will control

When the clear end distance or the clear bolt spacing is lessthan 2 bolt diameters, tear out strength will control

Generally, bolt spacing and end distances are standardized.

8

A standard bolt spacing of 3 inches is common. Thus,for all bolts of 7/8 inch diameter or less, only the end

bolt will need to be checked for tear out. Interior boltstrength will be controlled by bearing.


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Plate shear yielding

( )( )

5(0.6)(36)(9) 60.9 kips16

1.0 60.8 60.8 kips 45.0 kips ok

n

n

R

R

= =

= = >

9


Plate shear rupture

Block shear of plate

shear rupture/tension rupture

( )

7 51(0.6)(58) 9 3 65.3 kips8 8 16

0.75 65.3 49.0 kips 45.0 kips ok

n

n

R

R

= + =

= = >

10

54.3 kips 45.0 kips

ok

nR = >

7.5 in.

1.5 in.


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7/14


Try PL 3/4x7 in.

Check bearing on beam flange, which is more

critical than plate, for one bolt

For 8 bolts

( )( )72.4 (2.4)(65) 0.570 77.8 kips8n uR F dt= = =

13

( )

. ps

0.75 622 467 kips 167.0 kips ok

n

nR

= =

= = >


Check tension yielding of flange plate

Check tension rupture of flange plate

( )

(36)(7)(3/ 4) 189 kips

0.9 189 170 kips 167 kips ok

n

n

R

R

= =

= = >

7 31

14

( )8 8 4

0.75 218 164 kips 167 kips no good

n

nR = = <


8/14


Consider a 7.25 in. flange plate

( )( )( )

7 31(58) 7.25 2 228 kips8 8 4

0.75 228 171 kips 167 kips ok

n

n

R

R

= + =

= = >

15


Check block shear of flange plate

consider two possible failure patterns

4.0 in. 7.25 in.4.0 in.

A B

16

Based on the tension area, failure pattern B will be critical

for the plate. Pattern B in the beam flange is critical for this

case and will be checked.

. n. . n.


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Determine shear yield and shear rupture

Determine tension rupture, bf= 7.5 in.

( ) ( ) ( )[ ]

( ) [ ]

0.6 0.6 50 10.5 0.570 2 359 kips

7 10.6 0.6(65) 10.5 3.5 0.570 2 311 kips8 8

y g

u nv

F A

F A

= =

= + =

17


Block shear for pattern B with shear rupture thecontrollin term

Determine weld size, top and bottom of plate

( )

( )

311 92.6 404 kips

0.75 404 303 kips 167 kips ok

n

n

R

R

= + =

= = >

167

18

use a 3/8 fillet weld which is greater then theminimum

min . s xteent s2(1.5)(1.392)(7.25)= =


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Check the compression flange plate

The plate will be checked as a column with a

length of 2.0 inches and K= 0.65

The length comes from the end distance of 1.5

inches and the spacing of the beam to the column

of 0.5 inches

19

The K-factor is the recommended value for a

fixed/fixed column


Compression flange plate

From J4.4

3

2 20.7512 0.2165 in.12 12

bh

I hr

A bh= = = = =

20

( )0.65 2.0 6.00 250.2165

KL

r= =


11/14


Compression plate strength

( ) ( )

( )

36.0 ksi

36 (7.25) 0.75 196 kips

0.9 196 176 kips

cr y

n

n

F F

R

R

= =

= =

= =

21

Since the plate strength is greater than the

required 167 kips, the compression plate willbe the same as the tension plate.


Summary

top and bottom plates

8 -7/8 in. A325-N bolts each flange on a 4 inch

gage

3/8 in. fillet welds to su ortin column flan e

PL x 7 x 1'-0 "4 4 2

22

Check column for stiffening requirements


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Bolted Flange PlateBolted Flange Plate Column Side Limit StatesColumn Side Limit States

ens on ange oca en ng

( )26.250.90 (LRFD) 1.67 (ASD)

n f yR t F=

= =

23

( )

( . )( . ) ( ) ps

0.9 190 171 kips 167 kips ok

n

nR

= =

= = >


Tension web local yielding

Compression web local yielding

24

everything is the same as it was for tension

ok


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Compression - web crippling

Compression buckling

1.5

2 0.485 29000(50)(0.780)(0.8)(0.485) 1 3 kips14.2 0.780 0.

1.50332

332 24

485

0.75( ) kips 167 kips ok 9

n

n

R

R

= + =

= = >

25

since this is a one sided connection there will not

be compression buckling failure.


Panel Zone Shear

Without the knowledge of the lateral load on the

structure, this can not be checked; however, the

strength can be determined. Assuming the column

axial load is < 0.4Py

26

( )0.6 50 14.2 0.485 207 ps

0.9 207 186 kips

n

n

R

R= =

= =


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Welded flange plate connection

no reduction in beam moment strength

web shear plate design doesnt change

flange plate width to accommodate weld to

beam flange along edge of plate

no rupture of plate or beam flange

27

welds sized according to element thickness as

well as strength

Flange Plate Moment Connection

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