Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . s of Inertia.—These are here recapitu-lated for the simpler cases, and also the values of e. thedistance of the outermost fibre from the axis. Since the stiffness varies as /(other things being equal), 274 MECHANICS OF ENGINEERING. while the strength varies as I-^-e, it is evident that asquare beam has the same stiffness in any position (§89),while its strength is greatest with one side horizontal, forthen e
Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . s of Inertia.—These are here recapitu-lated for the simpler cases, and also the values of e. thedistance of the outermost fibre from the axis. Since the stiffness varies as /(other things being equal), 274 MECHANICS OF ENGINEERING. while the strength varies as I-^-e, it is evident that asquare beam has the same stiffness in any position (§89),while its strength is greatest with one side horizontal, forthen e is smallest, being —y^b. Since for any cross-section I— CdF z2, in which z=the distance of any element, dF, of area from the neutral axis,a beam is made both stiffer and stronger by throwingmost of its material into two flanges united by a verticalweb, thus forming a so-called I-beam of an I shape. Butnot without limit, for the web must be thick enough tocause the flanges to act together as a solid of continuoussubstance, and, if too high, is liable to buckle sideways,thus requiring lateral stiffening. These points will betreated later. *,— t i i FFR r i (a) (b) Fia. SECTION. I e Rectangle, width = b, depth = h (vertical) Via M» % h Hollow Rectangle, symmet. about neutral axis. See IFig. 238 (a) j Via [&i hS-b2 h\1 XK Triangle, width —b, height = h, neutral axis parallel Ito base (horizontal). f 736 bh* %fo Circle of radius r %nr* r Ring of concentric circles. Fig. 238 (b) JAMrA!-r*2) U Rhombus; Fig. 238 (c) h = diagonal which is vertical. 748 bh* %h Square with side 6 vertical. Via b* y2b b at 45° with horiz. Via b* HbV2 248. Moment of Inertia of I-beams, Box-girders, Etc.—Incommon with other large companies, the N. J. Steel and FLEXURE. SAFE LOADS. 275 Iron Co. of Trenton, N. J. (Cooper, Hewitt & Co.) manu-facture prismatic rolled beams of wrought-iron variouslycalled /-beams, deck-beams, rails, and shape iron, (in-cluding channels, angles, tees, etc., ac
Size: 2085px × 1198px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectenginee, bookyear1888
