The elasticity and resistance of the materials of engineering . pounds, and a = -qzitoFor solid wrought-iron columns, approximately:/ = pounds, and a = ^ji^o • 448 GORDONS FORMULA, [Art. 50. Experiments on steel columns are still lacking. Mr. , in his * Beams, Columns, and Arches, gives for Mild Steel, / = pounds, and a = -g-gToT*Strong Steel,/ = pounds, and a = yjJoo-- These, however, must be considered only loose approxima-tions for the ultimate resistance. In the ** Trans, of Am. Soc. Civ. Engrs., for Oct. 1880, aregiven the following formulae for
The elasticity and resistance of the materials of engineering . pounds, and a = -qzitoFor solid wrought-iron columns, approximately:/ = pounds, and a = ^ji^o • 448 GORDONS FORMULA, [Art. 50. Experiments on steel columns are still lacking. Mr. , in his * Beams, Columns, and Arches, gives for Mild Steel, / = pounds, and a = -g-gToT*Strong Steel,/ = pounds, and a = yjJoo-- These, however, must be considered only loose approxima-tions for the ultimate resistance. In the ** Trans, of Am. Soc. Civ. Engrs., for Oct. 1880, aregiven the following formulae for ultimate resistance of wrought-iron columns, designed several years since by C. Shaler Smith,: • Square Cohimn, / = FLAT I + 5820 d^ / = ONE PIN I + I I 3000 d^ P = TWO PIN ENDS. 375QOI 1900 d^ I +—-3-, Phcenix Column, 42500 I + ----7^ 4500 d P 40000 I 4- • - 2250 d ^6600 I + I 1500 d^ American Br, Co, Column, / = 36500 I + I I3750 d P 3^500 I A - 2250 d^ I H -7: 1750^ Art. 51.] COMMON AND PHCENIX COLUMNS. AA9 Common P 36500 ^^^A /- 36500 2700 d I + I P 36500 1500 d^ I + 7—:-r. 1200 d The formula for square columns may be used, withoutmuch error, for the common chord section composed of twochannel bars and plates, with the axis of the pin passingthrough the centre of gravity of the cross section. Compression members composed of two channels connectedby zigzag bracing, may be treated by the same formula afterputting 36, for 39, in Eqs. (21) and (22). Art. 51.—Experiments on Phoenix Columns,* Latticed Channel Columns and Channels. In May and July, 1873, some experiments were made atPhoenixville, Penn., on full sized Phoenix columns, by thePhoenix Iron Co. The results of these experiments are givenin column headed Experiment, while the column headed/** contains the results of the application of the formulaestablished in the preceding Article: / 42000 I + I 50000 r^ 42000or = I + I (0 50000 r- * The preceding Article was w
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