Identifier: stressesinstruct00wate (find matches)
Title: Stresses in structural steel angles : with special tables
Year: 1918 (1910s)
Authors: Waterbury, L. A. (Leslie Abram), 1880-1918
Subjects: Strains and stresses Steel, Structural Theses
Publisher: (New York : John Wiley & Sons)
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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of the section modulus. It will be observedthat by using the section modulus polygon, not only is therequired section modulus readily obtained, but also, the linesof the polygon which are intersected by the line of direc-tion of OP indicate the points of the section at which thecritical bending stresses will occur. In order to plot the section modulus polygon for a par-ticular section, the coordinates of each vertex of the polygonmay be determined, and the polygon can then be drawn byconnecting each two successive vertices with a straight line.If %ay Ja are the coordinates of a and xb, ybJ the coordinates ofb, two successive vertices of the polygon which bounds thesection, the coordinates xaby yab of the vertex of the sectionmodulus polygon corresponding to the side ab of the sectionwill be, xab — (xa - xb)J - (ya - yb)Iyxayb — xbya (14) yai> = (xa — xb)Ix — (ya — yb)Jxayb-xbya (i5) If ab is parallel to X-X, 8 STRESSES IN STRUCTURAL STEEL ANGLES If ab is parallel to Y-Y.
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Fig. 4. An inspection of Eqs. (14) to (19) will show that formany cases the vertices of the section modulus polygon can be easily located, since the values of - and - can be obtained y x from handbooks, for structural sections, and since / is zerofor symmetrical sections, which includes I-beams, channels, THEORY AND DISCUSSION 9 and tees. For angles, Eqs. (14) and (15) may be used, butin order that the users of this book may avoid this labor, thecoordinates have been computed and are tabulated at theback of the book for the commercial sizes of steel angles, andfor variations in thickness of ; inch. For thicknesses in oddnumbers of sixteenths of an inch, the values of the coordinatesmay be obtained by interpolation. A typical section modulus polygon for an angle is shownin Fig. 4. If OP represents the direction of the plane ofloading, the two points at which critical stresses will occurare b and d of the angle, but if the plane of loading is shiftedto OPr the points of critical stresse

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