NOTES ON THE STRENTH OF MATERIAL AND THE STABILITY OF STRUCTURES

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1870 Excerpt: ...83. The strength of wrought iron plates acting as struts, varies approximately as their width and as the cube of their thickness, and inversely as the square of their height or length; corresponding to formulas 31 and 32. To calculate the strength of struts, having the form of angle iron, T iron or double T iron, apply Gordon's formula 40, calling £ the thickness in the weakest direction; i. e., the direction in which it will give way, and considering separately the various parts into which it will be divided by planes parallel to that in which it would bend, for example, parallel to A B in Fig. 28. Fig; 28. Example. Length 8'. For A B a = 1.80 square inches; for G D a = 2.4" x.6" = 1.44 square inch, t--0.6". By Gordon's formula W = 53,748 pounds. 3D Actual breaking stress = 36,000, Using in the formula 24,000 instead of 36,000 would give the actual results. Experiments are wanting. Experiments by N. Y. C. E. E. give results indicating in the iron used in this form th§ proper values of g to be 6nly about 24,000. The strut $ the example, of English crown iron behaved as follows m the experiments. First experiment. Load in lbs. Flexure on 0 D. Load in lbs. Flexure on C D. 5,500.0 22,000.1875 8,200.050 24,700.220 10,900.075 27,500.250 13,700.100 30,200.312 16,500.125 No set Second experiment. Load in lbs. Flexure on C D. 22,000.126 30,400.5125 36,000 Bar bent almost double. Such experiments are very valuable and very scanty. For plate iron girders stiffened by T ribs, the depth across the ribs may be taken for t in Gordon's formula. For wrought iron cells, stiffened by angle iron, when the thickness of the plate is not less than fa of the diameter, the stress required to break them by bending is 27,000 pounds per square inch of the cro...