Flange Plate Moment Connection

Moment Connection – Bolted Bolted Flange Plate • Design Design a momen momentt connect connection ion usin using g a bolted bolted flange-plate • Connec Connectt a W18x5 W18x50 0 beam beam to the flan flange ge of a W14x99 column • Use 50 50 ksi wide wide-fla -flange ngess and 36 36 ksi plat plates es •

-

Ru

= 45.0 kips

M u

= 250 ft-kips 1

Moment Connection – Bolted Bolted Flange Plate • Co Conn nnec ecti tion on ge geom omet etry ry

2

1

Moment Connection – Bolted Bolted Flange Plate • Shapes – W18x50

= 18.0 in. b f = 7.50 in. Z x = 101 in.3 tw = 0.355 in. t f = 0.570 in. d

– W14x99

= . n. tw = 0.485 in.

f

= t f

.

n.

des

= 0.780 in.

=

.

n.

T = 10 in.

3

Moment Connection – Bolted Bolted Flange Plate • Proportion of members – hole reductions – – Where

Fu A fn

< Yt Fy A fg

Y t = 1.0 for

F y F u

≤ 0.8

(A992, A36)

= 1.1 otherwise

– then M n

=

u

A fg

fn

S x

– otherwise use full strength 4

2

Moment Connection – Bolted Bolted Flange Plate • With two holes per row, Fu A fn Yt Fy Afg

= (65)(3.13) = 204 kips = (1.0 ) (50)(4.28) = 214 kips

• since Fu A fn < Yt Fy A fg .

.

=⎜ = 352 ft-kips ⎟⎜ ⎟ ⎝ 4.28 ⎠ ⎝ 12 ⎠ φ M n = 0.9 ( 352 ) = 317 ft-kips > 250 ft-kips ∴ ok M n

5

Moment Connection – Bolted Bolted Flange Plate Single-plate web connection • bolt shear N =

45.0 21.6

= 2.08 ∴

use 3 bolts

– so try a PL 5/16 x 9 –

, p = . critical than the 0.355 in. web

.

6

3

Moment Connection – Bolted Bolted Flange Plate • Bearing on the plate ⎡ (2)(2.4)(58) ( 7 )( 5 ) + ⎤ 8 16 ⎢ ⎥ = ⎢⎛ ⎥ = 98.6 kips ⎞ 1 ⎛ ⎞ 7 5 ⎢⎜1.2 ⎜1.5 − ( + 1 ) ⎟ ( ) ( 58 ) ⎟ ⎥ 16 ⎠ 16 ⎢⎣⎝ ⎝ 2 8 ⎠ ⎥⎦

(

Rn

)

φ Rn = 0.75 ( 98.6 ) = 73.9 kips > 45.0 kips ∴ ok

7

Bolt Limit State When the clear end distance or the clear bolt spacing is greater than or equal to 2 bolt diameters, bearing strength will control When the clear end distance or the clear bolt spacing is less than 2 bolt diameters, tear out strength will control Generally, bolt spacing and end distances are standardized. 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 bolt strength will be controlled by bearing. 8

4

Moment Connection – Bolted Bolted Flange Plate • Plate shear yielding Rn

= (0.6)(36)(9) ( 516 ) = 60.9 kips

φ Rn = 1.0 ( 60.8 ) = 60.8 kips > 45.0 kips ∴ ok

9

Moment Connection – Bolted Bolted Flange Plate • Plate shear rupture Rn

= (0.6)(58) 9 − 3

7

8

+ 18

5

16

= 65.3 kips

= 0.75 ( 65.3) = 49.0 kips > 45.0 kips ∴ • Block shear of plate φ Rn

ok

– shear rupture/tension rupture

φ Rn = 54.3 kips > 45.0 kips ∴ ok

7.5 in.

1.5 in.

10

5

Moment Connection – Bolted Bolted Flange Plate • Determine required weld size between plate and . – No eccentricity Dmin

= =

Ru

9.0 in.

2(1.392 kips/in) l 45.0

= 1.80 → 2 sixteenths

2 1.392 9

– Based on the plate thickness, (between ¼ and ½ in.) use 2 - 3/16 welds (minimum weld size based on thinner part)

11

Moment Connection – Bolted Bolted Flange Plate • Design tension flange plate – determine flange force Puf

=

M u d

=

250(12) 18.0

= 167 kips

– consider bolt shear N =

Puf

φr n

=

167 21.6

= 7.78 → use 8 bolts

12

6

Moment Connection – Bolted Bolted Flange Plate • Try PL 3/4x7 in. – Check bearing on beam flange, which is more critical than plate, for one bolt Rn = 2.4 Fu dt = (2.4)(65) 7 ( 0.570) = 77.8 kips 8 – For 8 bolts

( )

. = ps = φ Rn = 0.75 ( 622 ) = 467 kips > 167.0 kips ∴ ok n

13

Moment Connection – Bolted Bolted Flange Plate • Check tension yielding of flange plate

= (36)(7)(3/ 4) = 189 kips φ Rn = 0.9 (189 ) = 170 kips > 167 kips ∴ ok Rn

• Check tension rupture of flange plate n

⎡ −

7

8

1

8

⎤3

4

φ Rn = 0.75 ( 218 ) = 164 kips < 167 kips ∴

no good

14

7

Moment Connection – Bolted Bolted Flange Plate • Consider a 7.25 in. flange plate Rn

= (58) ( 7.25 − 2 ( 7 8 + 18 ) ) 3 4 = 228 kips

φ Rn = 0.75 ( 228 ) = 171 kips > 167 kips ∴

ok

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Moment Connection – Bolted Bolted Flange Plate • Check block shear of flange plate – consider two possible failure patterns

4.0 in.

A

7.25 in.

4.0 in.

.

n.

.

n.

B

– 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. 16

8

Moment Connection – Bolted Bolted Flange Plate • Determine shear yield and shear rupture 0.6 F y Ag

= 0.6 ( 50)(10.5)( 0.570) [ 2] = 359 kips

0.6 Fu Anv

= 0.6(65) ⎡10.5 − 3.5 ( 7 8 + 18 ) ⎤ 0.570[ 2] = 311 kips ⎣ ⎦

• Determine tension rupture, b f = 7.5 in.

17

Moment Connection – Bolted Bolted Flange Plate • Block shear for pattern B with shear rupture the controllin term

= ( 311 + 92.6 ) = 404 kips φ Rn = 0.75 ( 404 ) = 303 kips > 167 kips ∴ Rn

ok

• Determine weld size, top and bottom of plate min

=

167 2(1.5)(1.392)(7.25)

=

.

→

s xteent s

• use a 3/8 fillet weld which is greater then the minimum 18

9

Moment Connection – Bolted Bolted Flange Plate • 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 – The K -factor is the recommended value for a fixed/fixed column

19

Moment Connection – Bolted Bolted Flange Plate • Compression flange plate bh r =

I A

=

3

12 bh

=

h2

12

=

0.752 12

= 0.2165 in.

• From J4.4 KL r

=

0.65 ( 2.0 ) 0.2165

= 6.00 < 25

20

10

Moment Connection – Bolted Bolted Flange Plate • Compression plate strength

Fcr

= F y = 36.0 ksi

= ( 36 ) (7.25) ( 0.75 ) = 196 kips φ Rn = 0.9 (196 ) = 176 kips

Rn

• Since the plate strength is greater than the required 167 kips, the compression plate will be the same as the tension plate. 21

Moment Connection – Bolted Bolted Flange Plate • Summary – top and bottom plates

PL

4

x7

4

x 1'-0 " 2

– 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

• Check column for stiffening requirements

22

11

Bolted Flange Plate – – Column Side Limit States

•

ens on – ange oca Rn

en ng

= ( 6.25t 2f F y )

φ = 0.90 (LRFD)

Ω = 1.67 (ASD)

ps = ( . )( . ) ( ) = φ Rn = 0.9 (190 ) = 171 kips > 167 kips ∴ ok n

23


• Tension – web local yielding

• Compression – web local yielding – everything is the same as it was for tension ∴ ok

24

12


• Compression - web crippling Rn

φ Rn

1.5 ⎡ 1.50 ⎞ ⎛ 0.485 ⎞ ⎤ 29000(50)(0.780) ⎛ = (0.8)(0.485) ⎢1 + 3 ⎜ = 332 kips ⎟⎜ ⎟ ⎥ 0.485 ⎝ 14.2 ⎠ ⎝ 0.780 ⎠ ⎥⎦ ⎢⎣ = 0.75(332) = 249 kips > 167 kips ∴ ok 2

• Compression buckling – since this is a one sided connection there will not be compression buckling failure.

25


• 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 < 0.4 P y

= 0.6 50 14.2 0.485 = 207 φ Rn = 0.9 ( 207 ) = 186 kips Rn

ps

26

13

Welded flange plate connection • no reduction in beam moment strength • web shear plate design doesn’t change • flange plate width to accommodate weld to beam flange along edge of plate • no rupture of plate or beam flange • welds sized according to element thickness as well as strength

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Flange Plate Moment Connection

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