| SPECIFICATIONS FOR STEEL IN BRIDGES, ETC. | 247 |
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Drillings for chemical analysis may be taken either from the preliminary test-piece or from the finished material.
The speed of the machine for breaking test-pieces shall not be less than one-quarter (1/4) inch per minute, nor more than three (3) inches per minute.
Material which is to be used without annealing or further treatment is to be tested in the condition in which it comes from the rolls. When the material is to be annealed or otherwise treated before use, the specimens representing such material may be similarly treated before testing; but they shall also give standard elongation, reduction, and fracture before annealing.
TENSILE STRENGTH.
The ultimate tensile strength per square inch on test-pieces for all three kinds of rolled steel used in structural metal-work shall be as follows: |
| Soft steel | 50,000 lbs. to 60,000 lbs. |
| Medium steel | 60,000 lbs. to 70,000 lbs. |
| High steel | 70,000 lbs. to 80,000 lbs. |
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ELASTIC LIMITS.
The least allowable elastic limits obtained from test-pieces and determined in the usual manner by the drop of the beam shall be as follows: |
| Soft steel | 30,000 lbs. per square inch. |
| Medium steel | 35,000 lbs. per square inch. |
| High steel | 40,000 lbs. per square inch. |
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ELONGATION.
The percentages of elongation shall be obtained from the test-pieces after breaking on an original length of eight (8) inches, in which length must occur the curve of reduction from stretch on both sides of the point of fracture. The least allowable elongations for the various kinds of rolled structural steel shall be as follows:
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