Elementary Applied Mechanics Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1883 edition. Excerpt: ...curved boom will bear a share of the shearing force; this compounded with the stress on the horizontal boom at the same section will give the resultant stress on the curved boom. It is usual in practice to make the area of the curved and of the straight booms uniform, and to make the diagonals sufficiently strong to resist the whole of the shearing force as in the previous case. Where the curved member slopes considerably, as in the Bowstring Girder, it is made sufficiently strong to bear the whole shearing force, the diagonals being intended for another purpose, viz.: to distribute partial loads in a sensibly uniform manner. The theoretical elevations reduce to a height zero at the ends, and so give no material to resist the shearing force at the point where it is greatest; sufficient material is generally allowed at the ends either by making the span of the girder exceed the clear span, or by departing from the theoretical form along a tangent near the end. Further, whatever the curves may be, and, as we have seen, they are generally parabolas, they are usually replaced by circles which nearly coincide therewith; when the figure passes from one curve to another, the passage is made along a tangent as will be seen on some of the figures. Approximate forms consisting entirely of straight lines enveloping the bending moment diagram, are sometimes adopted. Moment Of Resistance To Bending Of Rectangular And Triangular Cross Sections. The Moment of Resistance to Bending we have defined as the moment of the total stress upon the cross section about any point in it; and this we have shown, figs. 7, 8, 9, to be equal to the couple which is the moment of the normal stress on the cross section. The stress, fig. 8, might be artificially produced by...