44. Bearing For Beams

When the ends of beams rest upon walls, cast or wrought iron bed plates should be used to distribute the pressure over a greater surface. For buildings stone beds are generally used, but when the pressure is great both plates and stone. Beams have seldom less than 8 inches bearing or more than 12 inches; if less than 8 feet long, 6 inches will be sufficient.

45. Pressure On Brick And Stone Work

The pressure per square foot for brickwork should not exceed six tons, and for stone twelve to twenty tons, according to its character.

46. Knees For Beam Connections

The following sizes of knees are commonly used for beam connections:

24" into

24" beam =

6 X 4 X 1/2"

angles, 20"

long;

20" "

20" " =

6 X 4 X 1/2"

" 16"

"

15" "

15" " =

6X4X1/2"

" 11"

"

12" "

12" " =

6 X 4 X 1/2

" 8"

"

10 1/2" "

10 1/2" " =

6 X 4 X 7/16"

" 6 1/2"

"

10" into

10" beam

= 6 X 4 X 7/16"

angles, 6"

long;

9" "

9" "

= 6X4X7/16"

" 5"

8" "

8" "

= 5 X 3 1/2 X 3/8"

" 4 1/2"

"

7" "

7" "

= 5 X 3 1/2 X 3/8"

" 3 1/2"

"

6" "

6" "

= 5 X 3 1/2 X 3/8"

" 3"

"

5" "

5" "

= 5 X 3 1/2 X 3/8"

" 2 1/2"

"

4" "

4" "

= 3 1/2 X 3 1/2 X 3/8"

" 2 1/4"

"

47. Bolts And Rivets For Beam Connections

The number of bolts and rivets is determined by shearing and bearing strain. See article on "Bolts and Rivets".

48. Tee Irons As Beams

The following table gives:

Safe Load, In Pounds, Uniformly Distributed, For Tirons, Including Weight Of T

Maximum Strain 12,000 Pounds per Square Inch.

Size of T.

Weight per yard.

Coefficient for

Transverse

Strain.

Distance between Supports, in feet.

4

5

6

7

8

9

I0

11

12

flange

stem

th'kness

lbs.

5

X3"

X1/2"

38.1

7480

1870

1500

1250

1070

940

830

750

680

620

4 1/2

X3 1/2

x11/16

46.5

6010

1502

I200

IOOO

860

750

670

600

550

500

4

X5

X 1/2

45.6

24,800

6200

4960

4130

3540

3I00

,2770

2480

2250

2070

4

X4 1/2

X1/2

42.9

20,400

5100

4080

3400

2910

2550

2270

2040

1860

1700

4

X4

X1/2

37.5

I5,800

3950

3l60

2633

2257

1975

1755

1580

1435

1325

4

X3

XI

27.3

7070

1705

1414

1178

IOIO

884

785

707

634

589

3 1/2

X3 1/2

x1/2

27.O

9530

2382

1900

1590

1360

II90

IO60

950

870

790

3 1/2

X4

X3/8

29.1

12,380

3095

2476

2064

1770

I550

1380

1240

1130

1030

3 1/2

X3

x1/2

22.5

5790

1418

1l60

970

830

720

640

580

530

480

3

X4

x1/2

34.8

15,480

387O

3I00

2580

2210

1940

1720

I550

1410

1290

3

X3 1/2

x1/2

32.1

11,910

2975

2380

1990

1700

1490

1320

1190

1080

990

3

X3

x 5/16

19.5

5900

1475

Il80

980

840

740

650

590

540

490

3

X 2 1/2

X5/16

18.0

4100

I025

820

680

590

5IO

460

410

370

340

3

X 2

x 5/16

14.6

2540

637

508

423

363

317

283

254

231

212

2 1/2

X2 1/2

x 5/16

16.2

4000

I000

800

670

570

500

440

400

360

330

2 1/2

X3

x5/16

18.0

6110

1527

I220

1020

870

760

680

610

560

510

2 1/4

X 2 1/2

X9/32

11.90

2811

703

560

469

402

352

312

281

254

234

2

X 2

x1/4

9.4

I970

493

394

328

282

246

218

197

179

164

1 3/4

X 1 3/4

x1/4

9.0

1550

39°

310

260

220

190

170

155

140

130

1 1/2

X 1 1/2

x1/4

6.68

1033

258

207

172

147

129

115

103

94

86

I 1/4

XI 1/4

x7/32

4.87

596

149

119

98

85

75

66

59

54

49

I

X I

x5/32

2.80

268

67

53

45

38

36

29

26

24

22

49. Angle Irons As Beams

The following table gives:

Safe Load, In Pounds, Uniformly Distributed, For Equal-Leg Angles, Including Weight Of Angles

Maximum Strain 12,000 Pounds per Square Inch.

Size of

Angle.

Weight yard.

Coefficient for Transverse

Strength.

Distance between Supports, in feet.

4

5

6

7

8

9

10

XX

12

inches.

lbs.

6 X6 X7/16

50.6

32,560

8140

6510

5430

4650

4070

3620

3260

2960

2715

6 X6 X1/2

57.5

36,900

9225

7400

6150

5270

4612

4100

3690

3354

3075

5X5X 3/5

36.0

19,360

4840

3870

3230

2770

2420

2150

1940

1760

1618

4 1/2 X 4 1/2 X A

37.5

18,000

4500

3600

3000

2571

2250

2000

1800

1633

1500

4 X4 XI

28.6

12,184

3046

2437

2031

1740

1523

1354

1218

1107

1015

3 1/2 X 3 1/2 X 3/8

24.8

9200

2300

1840

1530

1310

1150

I020

920

840

770

3 X3 X 1/4

14.4

4611

"53

922

767

658

576

512

461

419

384

2 5/4 X 2 3/4 X 5/16

16.2

4710

1177

942

785

672

589

522

471

428

393

2 1/2 X 2 1/2 X 1/4

11.9

3156

789

631

526

45T

394

344

317

287

263

2 1/4 X 2 1/4 X 1/4

10.6

2530

633

506

422

362

316

281

253

230

211

2 X 2 x 7/32

8.3

1752

438

350

292

250

219

195

175

159

146

1 3/4 x 1 3/4 x 3/16

6.21

II50

287

230

I92

164

144

128

"5

104

96

1 1/2 x 1 1/2 x 3/16

5.27

832

208

164

139

119

104

92

83

76

69

1 1/4 X 1 1/4 X 1/8

2.97

393

98

78

65

56

49

44

39

36

33

50. Safe Load For Unequal-Leg Angles, The Longer Leg Vertical

Maximum Strain 12,000 Pounds per Square Inch.

Size of

Angle.

Weight per yard.

Coefficient for Transverse

Strength.

Distance between Supports, in feet.

4

5

6

7

8

9

10

11

12

inches.

lbs.

6 X4 X 7/16

41.8

30,680

7670

6136

5113

4383

3834

3409

3068

2789

2556

6 X4 X3/8

36.1

26,560

6640

53IO

4430

3790

3320

2950

2660

2410

22I0

6 X 3 1/2 X 3/8

34.2

26,000

6500

5200

4330

3710

3250

2890

2600

2360

2I70

5 X4 X3/8

32.3

18,720

4680

3740

3I20

2670

2340

2080

1870

1700

I560

5 X3 1/2X 3/8

30.5

18,353

4590

3671

3059

2622

2294

2038

1835

1668

1528

5 X3 X 3/8

28.6

17,840

4460

3570

2970

2550

2230

1980

1784

1620

I490

4 1/2X3 X3/8

26.7

14,580

3645

2916

2430

2083

1823

1620

1458

1325

I217

4 X3 1/2X 3/8

26.7

I2,000

3000

2400

2000

1710

1500

I330

I200

I090

1000

4 X3 X5/16

20.9

9850

2462

1970

1641

1407

1231

I094

985

895

821

3 1/2X3 X5/16

19.3

7680

1920

I540

1280

1100

960

850

770

700

640

3 1/2 X 2 1/2 X 1/4

14.4

6000

I500

I200

10000

860

750

670

600

540

500

3 X 2 1/2 X 1/4

I3.I

4480

1120

900

750

640

560

500

450

410

370

3 X2 X1/4

II.9

4320

1080

860

720

620

540

480

430

390

360

2 1/2X2 x3/16

8.1

2320

580

460

390

330

290

260

230

210

190

51. Beams Not Uniformly Loaded And Beams Not Supported At Both Ends

(a) For a beam fixed at one end and loaded at the other as a cantilever, coefficient/8L. Safe load in lbs. =

(6) For a beam fixed at one end and uniformly loaded, coefficient/4L Safe load in lbs. =

(c) For a beam supported at both ends, load concentrated at any point,

Safe load in lbs. =(coefficient/L)x (L2/(8AxB)

A = distance from load to one support; B = distance from load to the other support.

Note. - The beams, channels and other shapes treated of in this chapter are selezcted from the hand-books of the Passaic Rolling Mill Co., Phoenix Iron Co., Columbia Iron and Steel Co., and Pottsville Iron and Steel Co.