. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . counter-braces m, m, are nec-essary. Fig. 64. I^DHHjj^^^^^^K IB^^^^^BBhH^^^HIIBI The pieces A c A! c^ must support all of the load, includingthe weight of the bridge, lying within the rectangle B c B next set of braces must sustain that part of the loadonly which comes over the centre of the bridge. Thus thebraces should decrease in size as the centre is approa
. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . counter-braces m, m, are nec-essary. Fig. 64. I^DHHjj^^^^^^K IB^^^^^BBhH^^^HIIBI The pieces A c A! c^ must support all of the load, includingthe weight of the bridge, lying within the rectangle B c B next set of braces must sustain that part of the loadonly which comes over the centre of the bridge. Thus thebraces should decrease in size as the centre is rods c B, c B, must resist a tension equal in amountto the pressure on the braces, only being vertical they donot need the increase given to the braces on account of theirinclination. 177. There is another method of stiffening a beam, asshown in figs. 65 and 66, by trussing rods, and a post. Thedimensions being the same, the forces in both cases will beequal. The second, fig. 66, leaves the passage beneath thebridge clear. The tension on therods Ac, Be, fig. 66,tends to draw the pointsA and B together, aneffort which is resistedby the top chord A extending this system, as in art. 176, the rods become Fig. WOODEN BRIDGES. 145
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectrailroadsdesignandco
