Tests of large bridge columns. . n §0 inches for the extreme filaments atthe mid lengths of column are platted as the abscissas of thecurves. (See data of Tables 6, 7, 9, 10, 16, 18, and 20.) Theseabscissas are proportional to the mean stresses / at the respectivestations when the modulus of the column is considered a average curve is also platted as has been done elsewhere forall the columns, its abscissa being g0. The distance g-g0 along aparticular abscissa between the average curve and the curve cor-responding to a given station is proportional to the bending stressf-p at the
Tests of large bridge columns. . n §0 inches for the extreme filaments atthe mid lengths of column are platted as the abscissas of thecurves. (See data of Tables 6, 7, 9, 10, 16, 18, and 20.) Theseabscissas are proportional to the mean stresses / at the respectivestations when the modulus of the column is considered a average curve is also platted as has been done elsewhere forall the columns, its abscissa being g0. The distance g-g0 along aparticular abscissa between the average curve and the curve cor-responding to a given station is proportional to the bending stressf-p at the station. It will be seen that g-gQ as a rule is constant 102 Technologic Papers of the Bureau of Standards above a critical value of mean stress, pc = 5000 pounds per squareinch, as was already found analytically in the case of column other words, the curves are generally equidistant above theordinate pc. This general parallelism of the curves is character-istic of the whole series of columns. There is, however, a diver-. S>t .02 o .0/ .02 .03 o .0/ 3 .04 inohes Fig. 63.—-Typical stress deformation curves gence instead of a parallelism of curves in the case of column US2-MS! (carbon). Enough observations were taken in the case ofcolumns HC and MY to show definitely that there is practically aradial divergence of the curves below the critical value pc; in otherwords, neglecting minor departures and curvatures, the stress / is Tests of Large Bridge Columns 103 a linear function of p for low loads. The law for the larger numberof columns of the series may therefore be stated analytically to areasonable degree of approximation:
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