978-1337094740 Chapter 8 Part 6

Base metal shear strength of column web:

Rupture: Rn0. 45Futw20. 45650. 3702

8.8–1

(a) LRFD solution

Factored shear and moment:

Vu1. 20. 25 271. 60. 75 2740. 5 kips

Mu1. 20. 25 671. 60. 75 67100. 5 ft-kips

Is required moment strength at least 60% of available moment strength?

Tensile strength: Ab0. 752/4 0. 441 8 in.2

RnFntAb0. 75900. 441829. 82 kips/bolt 22.6 kips/bolt (OK)

Shear load per bolt 40. 5/4 10. 13 kips (compression side bolts)

Bearing strength: Assume that the bearing deformation strength of 2.4dtFucontrols and

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that column flange thickness controls (tf0. 435 in.).

Is required moment strength at least 60% of available moment strength?

Mn

Mp

82. 8 ft-kips, 0. 6082. 849. 7 ft-kips

8.8–2

LRFD solution

Factored shear and moment:

Vu1. 20. 25 531. 60. 75 5379. 5 kips

Mu1. 20. 25 1341. 60. 75 134201. 0 ft-kips

Is required moment strength at least 60% of available moment strength?

8.8–3

LRFD solution

From the Zxtables, for a W18 40,

MubMpx 294 ft-kips

VuvVn169 kips

Fth0h12294 12

0. 759019. 64 15. 110. 979 in.

Try db1 inch.

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Moment strength based on bolt strength:

PtFtAb9012/4 70. 69 kips/bolt

6. 02 17. 02 in.

Try bp7 in. Compute the required plate thickness:

s1

215. 11 1

21

2. 475 19. 64 1

2−1

22

3. 5 15. 1122. 475

119. 1

Required tp1. 11Mn

bFyYp

1. 113528

0. 936119. 11. 01 in.

Try tp1¼ inch.

0. 6FuAn0. 750. 6585. 781150. 9 kips 101.6 kips (OK)

Check bolt shear. The compression side bolts must be capable of resisting the entire

vertical shear.

Abdb

2

Recompute the plate dimensions. For 1¼-inch diameter bolts,

minimum ℓe15

8in.

The minimum plate width is

g2ℓe3. 50 21. 6256. 75 in.

Tearout: Rn1. 2ℓctFu0. 751. 23. 0871. 2558201. 4 kips

Bearing deformation: 2. 4dtFu0. 752. 41. 251. 2558163. 1 kips

Since the inner bolts are not near an edge or adjacent bolts, the outer bolts control for

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bearing. However, the shear strength of 49. 69 kip/bolt controls for each bolt.

8222 1 5

825 1

8in.

UseaPL1¼72′−11

8

′′

and four 1¼-inch diameter Group A fully-tightened bolts at each flange.

1. 392D11. 73 1. 5 203. 1, D8. 29 sixteenths

From AISC Table J2.4, the minimum weld size is ¼ in. (based on the thickness of the

1. 392D20. 6Fytw

1. 39220. 6500. 315

1. 39223. 39 sixteenths

1. from mid-depth to the compression flange:

2. from the inner row of tension bolts plus 2dbto the compression flange:

1. 392D8. 425 2169, D7. 21 sixteenths (w½ in.)

From AISC Table J2.4, the minimum weld size is 3/16 in.

Use a ½-inch fillet weld on each side of the web

between mid-depth and the compression flange.

The design is summarized in the figure below.

7″

9/16

2″

1 5/8″

Not to scale

8.8–4

LRFD solution

Vu1. 2131. 63470. 0 kips

Mu1. 2201. 648100. 8 ft-kips

dbReq′d2Mu

Fth0h12100. 8 12

0. 759014. 08 9. 640. 694 in.

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s1

2bpg1

27. 523. 5

2. 565 in. pfi ∴use the original value of pfi 2. 0 in.

Ypbp

pfi

1

sh01

pfo

−1

gh1pfi s

29. 64 1

21

2. 565 14. 08 1

2−1

22

3. 5 9. 6422. 565

81. 99

Required tp1. 11Mn

bFyYp

1. 111415

0. 903681. 990. 769 in.

87. 52 −23

41

85. 049 in.2

0. 6FuAn0. 750. 6585. 049132 kips 51 kips (OK)

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Check bolt shear. The compression side bolts must be capable of resisting the entire

vertical shear.

2

ℓcpfo tfb pfi −h20. 440 2−13/16 3. 628 in.

Tearout: Rn1. 2ℓctFu0. 751. 23. 6287/858165. 7 kips

Bearing deformation: 2. 4dtFu0. 752. 43/47/85868. 51 kips

Since the inner bolts are not near an edge or adjacent bolts, the outer bolts control.

Shear controls overall.

881′−63

8

4-inch diameter Group A fully-tightened bolts at

each flange.

AISC Design Guide 4 recommends that the minimum design flange force should be

1. 392D12. 78 1. 5 102. 0, D3. 82 sixteenths

From AISC Table J2.4, the minimum weld size is 3/16 in. (based on the thickness of

1. 392D20. 6Fytw

1. 39220. 6500. 260

1. 39222. 80 sixteenths

Minimum size 3/16 in., based on web thickness.

1. from mid-depth to the compression flange:

2. from the inner row of tension bolts plus 2dbto the compression flange:

1. 392D5. 71 270, D4. 40 sixteenths

Use a 5/16-inch fillet weld on each side of the web between mid-depth and

the compression flange.

The design is summarized in the following figure .

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8″