Width of Span Between Beams.

Depth of Arch.

Weight per Square Foot,

3 feet 6 inches to 4 feet 0 inches.

6

inches.

27

pounds.

4

0

,,

4

6

,,

7

,,

29

,,

4

6

,,

5

0

,,

8

,,

32

,,

5

6

,,

6

0

,,

9

,,

36

,,

6

0

,,

6

6

,,

10

,,

39

,,

6

6

,,

7

0

,,

12

,,

44

,,

Partitions

Thickness.

Weight per Square Foot

Hollow Brick (Clay) Partitions

2

inches.

11

pounds.

,,

,,

,,

,,

3

,,

14

,,

,,

,,

,,

,,

4

,,

15

,,

,,

,,

,,

,,

6

,,

19

,,

,,

,,

,,

,,

6

,,

20

,,

,,

,,

,,

,,

8

,,

27

,,

Porous Terra-Cotta Partitions

3

,,

16

,,

,,

,,

,,

,,

4

,,

19

,,

,,

,,

,,

,,

5

,,

22

,,

,,

,,

,,

,,

6

,,

23

,,

,,

,,

,,

,,

8

,,

33

,,

partitions - (Concluded).

Thickness

Weight per Square Foot

Porous Terra-Cotta Furring

2

inches.

8

pounds.

,,

,,

,,

Roofing

2

,,

12

,,

,,

,,

,,

,,

3

,,

15

,,

,,

,,

,,

,,

4

,,

19

,,

,,

,,

,,

Ceiling

2

,,

11

,,

,,

,,

,,

,,

3

,,

15

,,

,,

,,

,,

,,

4

,,

19

,,

6

inch Segmental Arches.

27 pounds per square foot.

8

,,

,,

,,

33

,,

,,

,,

,,

2 inch Porous Terra-Cotta Partition, 8 lbs. per square foot.

The following table shows the safe loads in pounds per square foot uniformly distributed for hollow-tile floor arches.

Table XV. Safe Loads Uniformly Distributed For Hollow-Tile Arches

Nominal Depth.

Effective

Depth.

R

Span of Arch in Feet = L

Inches.

Inches.

3

4

5

6

7

8

6

3.6

336

189

121

7

4.6

429

242

155

8

6.6

523

294

188

131

9

6.6

616

347

222

154

113

10

7.6

709

399

255

177

130

100

12

9.6

896

504

323

224

165

126

Gross loads in pounds per square foot, i. e., including weight of arch. Safety factor 6.

Nominal Depth.

Effective

Depth.

R

Weight of Arch per

Square Foot

Span of Arch in Feet = L.

Inches.

Inches.

Pounds.

3

4

6

6

7

8

6

3.6

27

309

162

94

7

4.6

29

400

213

126

8

5.6

32

481

262

156

99

9

6.6

36

580

311

186

118

77

10

7.6

39

670

360

216

136

91

61

12

9.6

44

852

460

279

180

121

82

Net loads in pounds per square foot, i. e. excluding weight of arch. Safety factor, 6. The formula for safe load used in computing the above table is as follows:

W = 840 R/L2

In which

W = Safe load per square foot of arch in pounds. R = Rise or effective depth of arch in inches. L = Spar of arch in feet.

In the following table are given, in pounds per square foot, the weights of various materials used in floor and roof construction.

Table XVI. Weights Of Materials In Floor And Roof Construction

SUBSTANCE.

AVERAGE WEIGHT IN

POUNDS

PER SQUARE FOOT.

Corrugated galvanized iron, No. 20

2 1/2

Copper, 16-oz. - Standing seam

1 1/4

Glass, 1/4 inch thick

3 1/2

Cinder-concrete filling, 2-inch, including screeds

12

Plaster, on wood latth (no furring)

6 to 8

Plaster, on metal lath (no furring)

8 to 10

Plaster ceiling, suspended

15 to 20

Roofing felt, 2 layers

1/2

Slate, 1/8 inch thick, 3 inches double lap

4 1/2

Shingles, 1/3 to weather

2

Gravel composition roof, 5 ply

9 to 11

Tin, 1X

Tiles, 6 1/4 in. X 10 1/2 in. - 5 1/4 in, to weather (plain)

17

Tiles, 10 1/2 in. X 14 1/2 in. - 7 1/4 in. to weather (Spanish)

9

Trusses - Spans under 50 feet

3 1/2 to 4 1/2

Trusses - Spans 50 to 75 feet

4 1/2 to 6 1/2

Trusses - Spans 75 to 100 feet

6 1/2 to 8