. The railroad engineer's practice . ine of the bridge. Abroad it is often made to batter in aplane parallel to the centre line, but as the force due to thewind acting to overturn it is greater, when the structureis very high, than the reaction due to the force on the driv-ing wheel, the additional strength due to the greater lever-age obtained by spreading the base should be opposed tothe wind pressure. The high piers built by American en-gineers usually batter at one and one-half inch to a foot,but the columns at opposite sides of the bi-idge are in ver-tical planes at right angles to it. Th
. The railroad engineer's practice . ine of the bridge. Abroad it is often made to batter in aplane parallel to the centre line, but as the force due to thewind acting to overturn it is greater, when the structureis very high, than the reaction due to the force on the driv-ing wheel, the additional strength due to the greater lever-age obtained by spreading the base should be opposed tothe wind pressure. The high piers built by American en-gineers usually batter at one and one-half inch to a foot,but the columns at opposite sides of the bi-idge are in ver-tical planes at right angles to it. The following formulasrepresent the strains ia the several parts of such a pier inone of these vertical planes. Let J* = the pressure due to the wind on the train, andtrusses on one pair of columns, found by multiplying theside surface in square feet of a train covering half of eachadjacent span and the exposed surface of the half spansthemselves by the maximum pressure of the wind on asquare foot. Let P = the pressure due t) the wind. on one panel of the pier, on one pair of columns, foundby multiplying one-half the surface exposed on the adja-cent sides of the bent, by the maximum pressure of thewind. Let W = the vertical load due to train and bridge onone column ; for the outer columns it will be one-half theload on the adjacent spans of bridge and pier. Let W^ = the vertical load due to one panel of the pieron one column. Let « = the angle made by the columnswith the vertical. The batter is usually, in American struc-tures, Iv inches to a foot, when « will = 7 8, Let /^, fj, P, etc., = the successive angles which thediagonal braces make with the vertical, from the top down>wards. Then, Strain on H B = P + W tan. a + J- W tan. a compression, I sin. (/J — a) Strain on AC = P sin. (/J + a) + P + W tan, rt compression. 85Strain on sin. {/J + ex) sin. {fi + a) siu. {(i + a) tan. on mCjt = Jr h P sin. (J3 + a) sin. (/i + ex) sin. {fi + a) sin. (/i + a^ sin. {(3 —a
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Keywords: ., bo, bookcentury1800, bookdecade1880, bookidrailroadengineer00clee
