SAFE LOADS AND BREAKING LOADS.

The following table gives the safe working loads allowable in good practice for brickwork, masonry, and foundation soils; in other words, calculations may be based directly on the values given, without using any factor of safety.

SAFE BEARING LOADS.

Brick and Stone Masonry.

Brickwork.

Bricks, hard, laid in lime mortar
Hard, laid in Portland cement mortar..
Hard, laid in Rosendale cement mortar....

Masonry.

Granite, capstone
Squared stonework
Sandstone, capstone.

Squared stonework

Rubble stonework, laid in lime mortar
Rubble stonework, laid in cement mortar

Limestone, capstone.

Squared stonework

Rubble, laid in lime mortar

Rubble, laid in cement mortar

Concrete, 1 Portland, 2 sand, 5 broken stone

Lb. per
Sq. İn.

100

200

150

700

350

350

175

80

150

500

250
80

150

150

Tons

per Sq. Ft.

100 25-40 15-20

4-6

2-4

1-2

8-10

4-6

2-4

.5-1

BREAKING LOADS FOR ROUND CAST-IRON

COLUMNS.

(In Thousand Pounds.)

Length of Column in Feet.

8 ft. 10 ft. 12 ft. 14 ft. 16 ft. 18 ft. 20 ft.

418

505 412

1,000
1,120

570 465 374

651 525 423

560 474 393
655 566 476

820 658 544

880

732

971

810

850 735

631

910

743

960

810

1,260 1,082 930
1,360 1,185 1,005
923

865

810

710

620

1,040
1,220 1,073

950

820

720

1,360 1,200 1,050

918

805

1,039

900

758

958 851

900

798

705

910

820

895

980

1,000

895

990

1,550 1,362 1,192
1,710 1,500 1,300 1,130
1,420 1,280 1,141 1,020
1,640 1,495 1,318 1,170 1,036
1,830 1,580 1,460 1,292 1,143
2,030 1,810 1,470 1,310 1,160
1,640 1,510 1,363 1,260 1,120
1,840 1,680 1,540 1,385 1,250 1,113
2,100 1,923 1,740 1,570 1,420 1,258 | 1,119
2,300 2,110 1,920 1,720 1,550 1,370 1,217
1,869 1,740 1,600 1,440 1,310 1,200 1,080
2,130 1,960 1,800 1,630 1,490 1,360 1,223
2,380 2,180 2,020 1,840 1,670 1,500 1,360
2,580 2,350 2,180 1,990 1,800 1,620 1,470
2,020 1,900 1,740 1,620 1,480 1,363
2,400 2,250 2,100 1,920 1,760 1,590 1,465
2,660 2,480 2,320 2,120 1,940 1,745 1,610
2,920 2,720 2,540 2,310 2,120 1,900 1,750
2,600 2,450 2,310 2,160 1,970 1,820 1,670
2,930 2,700 2,580 2,390 2,140 2,090 1,880
3,250 3,090 2,850 2,670 2,440 2,300 2.070
3,560 3,360 3,140 2,910 2,660 2,440 2,250

1,265

610

670

347

332 270

332

287

384

324

425

360

470 396

462

400

545

468

620

529

675

578

732

625

535

628

595 614

682

751

402

456

510

559

542

640

710

785

1,010

1,110

280

313

339

352

405

455

502

545

480

560

SAFE UNIFORMLY DISTRIBUTED LOADS FOR REO. TANGULAR WOODEN BEAMS 1 INCH THICK.

Depth of Beam.

5 800 1,090 1,420 4,800 2,220

Safe load for any thickness

MATERIALS OF CONSTRUCTION.

STONE.

Granite is the most valuable stone where strength is required, its crushing strength averaging about 20,000 lb. per sq. in. Exposed to fire, it disintegrates at a temperature of from 900° to 1,000° F., being less durable in this respect than fine-grained, compact sandstones. The average weight oi granite is about 167 lb. per cu. ft.

Limestone is a very common building stone, and, when compact, is very durable. It is usually quite absorptive, and becomes dirty quickly; while under intense heat, it is converted into lime. Limestone must be well seasoned before use, to get rid of the quarry water. The strength of lime stone varies from 7,000 to 25,000 lb. per sq. in., the average being about 15,000 lb. The weight of limestone is about 155 to 160 lb. per cu. ft.

Sandstone is, in general, an excellent building stone, capable of resisting great heat, and the better kinds absorb only small quantities of water. The dark-brown, flinty sand. stones retain their color very well, ranking better than granite. A stone containing much pyrites becomes unevenly discolored, due to formation of rust, and, hence, the stone should be carefully examined in this respect. The average strength of sandstones is about 11,000 lb. per sq. in., varying from 4,000 to 17,000 lb. The weight of sandstone is about 140 ib. per cu. ft.

When a good stone is tapped with a hammer, it gives out a ringing sound. The absorptive quality of a stone may be tested by noting the increase in weight after soaking in water for 24 hours. One that increases 5 per cent. or more should not be used.

BRICK.

If two good bricks are struck together, they give out a ringing sound; while if the sound is dull, the brick is of inferior quality. A good brick will not absorb more than 10 per cent. of its weight of water; the best will not absorb over 5 per cent., while soft brick will take up from 25 to 35 per cent

CEMENTS.

81 81%

TERRA COTTA.

Solid terra cotta weighs about 120 lb. per cu. ft., while hollow pieces of ordinary size average from 65 to 85 lb. The safe working strength of terra-cotta blocks in walls is about 5 tons per sq. ft., if unfilled, and 10 tons, if filled solid with concrete

LIME.

Lime weighs about 66 lb. per bu., or about 53 lb. per cu, ft. One barrel of lime, weighing 230 lb., will make about 24 bbl., or .3 cu. yd., of stiff paste. In 1-to-3 mortar, 1 bbl. of unslaked lime will make about 64 bbl. of mortar; or 1 bbl. of lime paste will make about 3 bbl. of mortar. For a 1-to-2 mortar, about 1 bbl. of quicklime to 5 or 5 bbl. of sand are used.

The two kinds of hydraulic cements are termed Portland and natural (often called Rosendale, from a place in New York where much of it is made).

Portland cements are dark in color, weigh from 90 to 100 lb. per cu. ft., are very slow in setting, and attain great ultimate strength. Natural cements are light in color, weigh from 50 to 60 lb. per cu. ft., are very quick setting, and become from to as strong as Portland cement.