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 . ing loads, or vibrations)it may move to the edge of the middle third, causing themax. pressure to be double the mean (per square inch). Gen. Gillmores experiments in 1876 gave the followingresults, among many others : NAME OF BUILDING STONE. C IN LBS. PER SQ. INCH. Berea sand-stone, 2-inch cube, - 8955 4 - 11720 Limestone, Sebastopol, 2-inch cube - 1075 Marble, Yermont, 2-inch cube, - > 8000 to 13000 Grani
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 . ing loads, or vibrations)it may move to the edge of the middle third, causing themax. pressure to be double the mean (per square inch). Gen. Gillmores experiments in 1876 gave the followingresults, among many others : NAME OF BUILDING STONE. C IN LBS. PER SQ. INCH. Berea sand-stone, 2-inch cube, - 8955 4 - 11720 Limestone, Sebastopol, 2-inch cube - 1075 Marble, Yermont, 2-inch cube, - > 8000 to 13000 Granite, New Hampshire, 2-inch cube, 15700 to 24000 349. The Three Conditions of Safe Equilibrium for an arch ofuncemented voussoirs. Recapitulating the results of the foregoing paragraphs,we may state, as follows, the three conditions which mustbe satisfied at every joint of arch-ring and pier, for eachof any possible combination of loads upon the structure : (1). The resultant pressure must pass within the middle-third. (2). The resultant pressure must not make an angle >30° with the normal to the joint. (3). The mean pressure per unit of area on the surface* ARCH OF MASONRY. 425. of the joint must not exceed 1/20 of the Modulus of crush-ing of the material. 350. The True Linear-Arch, or Special Equilibrium Polygon; and the resultant pressure at any joint. Let the weightof each voussoir and its load be represented by a verticalforce passing through the centre of gravity of the two, asin Fig. 381. Taking anytwo points A and B, Abeing in the first joint andB in the last; also a thirdpoint, p, in the crownjoint (supposing such tobe there, although gener-ally a key-stone occupiesthe crown), through these pig. 38i. three points can be drawn [§ 341] an equilibrium polygonfor the loads given ; suppose this equil. polygon nowherepasses outside of the arch-ring (the arch-ring is the por-tion between the intrados, mn, and the (dotted) extradosmn) intersecting the joints at b, c, etc. E
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectenginee, bookyear1888
