Letter from the Secretary of war in response to Senate resolution of December 10, 1894, transmitting the report of the Board of Engineers and bridge-b . stortion of the floor causes a grade of less than 1 per cent. Hence thisstiffening girder was calculated for a moving load of 15,000 pounds. To comply with this condition and not to strain the metal above 15,000 pounds persquare inch, the height of the truss was chosen to be 120 feet giving the following-dimensions : Maximum chord, section of either top or bottom chords square inches. 1, 395 Average weight of both chords pounds per linear foot
Letter from the Secretary of war in response to Senate resolution of December 10, 1894, transmitting the report of the Board of Engineers and bridge-b . stortion of the floor causes a grade of less than 1 per cent. Hence thisstiffening girder was calculated for a moving load of 15,000 pounds. To comply with this condition and not to strain the metal above 15,000 pounds persquare inch, the height of the truss was chosen to be 120 feet giving the following-dimensions : Maximum chord, section of either top or bottom chords square inches. 1, 395 Average weight of both chords pounds per linear foot. 8,000 Average weight of web svtem do 4,220 Total do ....12,280 It will be found that the deflection of this truss for a load of 15,000 pounds perlinear foot is feet if the elongations and contractions of the web members beneglected; hence its true deflection will about coincide with the distortion of thecable under a load of 2,400 pounds per linear foot. 72 BRIDGE ACROSS THE HUDSON RIVE1?. The intermediate floor-beam suspenders and cross-bracings were calculated for alocal load of 200 tons, in addition to the dead weight on each I I I I I T T T T I T T T T T T 20$ t. 209 t. Allowing a unit strain of 20,000 pounds per square inch, the weight of these partswill be 1,332 pounds per linear foot. The question was investigated whether there was an appreciable inclination ofthe floor beams if three tracks on one side of the axis of the bridge were fullyloaded of the spans, and if the opposite three tracks were loaded in theother half of *<4io span. For instance, a load of 9,000 pounds per linear foot on thethree right-hand tracks will depress the right end of the floor beams feet andthe left end foot. The same load on the left three tracks in the opposite halfspan will raise the right ends of the former floor beams foot, and will depressthe left ends feet; hence, the greatest inclination of a floor beam is feet in100 feet, whi
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherwashi, bookyear1894
