. Design of a three span double track reinforced concrete railroad arch bridge . l^/sis of the arch the effect of j- has heen oi^iitted. TBy it has beer, determined that the effect of t is to decrease the value of H. The experiments of Prof. Hov;eh^ve shown that for an arch havinfi; a rise of ■5- the span, the truevalue of H is 93-l/2> of the approximate value; for a rise of1/6, S6;o; and for a rise of l/lO, 69:1. In the arch, designed,the rise was 3 feet 10 inches, and the span 32 feet, giving aratio of o—^-r* S interpolating between the values already men-tioned the correct p
. Design of a three span double track reinforced concrete railroad arch bridge . l^/sis of the arch the effect of j- has heen oi^iitted. TBy it has beer, determined that the effect of t is to decrease the value of H. The experiments of Prof. Hov;eh^ve shown that for an arch havinfi; a rise of ■5- the span, the truevalue of H is 93-l/2> of the approximate value; for a rise of1/6, S6;o; and for a rise of l/lO, 69:1. In the arch, designed,the rise was 3 feet 10 inches, and the span 32 feet, giving aratio of o—^-r* S interpolating between the values already men-tioned the correct percentage for H v;as determined. True Pole Distance = ;b of the approximate value. Having determined the trte pole distance, a nev; stressdiagram and equilibrium polygon vras drav/n. e and e, being pointson the required curve, the new polygon must he drawn from one ofthese points, and as a on the accuracy of the work, itshould pass through the other point. Ilie pret^suro curve having been located, it only to determine the unit stresses UNIT 5TRE35E5 H*. The above figure is a side view of a portion of an archring contained between two planes perpendicular to the neutralsurface n n and mahing an angle oc in circuJLar measure, beforestrain, between them. A vertical plane ir^idway between the facesof the arch intersects the neutral surface in the line n n = Asfeet in length, v/hicZi may be calJed the neutral line. The forcesconsidered all act in this plane. Let R be the resultant of all external forces acting uponthe section passing through r . Conceive a;pplied at n tvTO opposedforces +R and -R, each equal and parallel to R. The single forceR is thus replaced hv a couple RR and a force +R acting at latter may be resolved into components T and IT, tangential andnormal to n n at n. The force T causes a unifon:i shortening inall the fibres. The force N is a s}ieari:ig force and jnaiT- be neglected in de-termining the longitudinal stresses. The couple RK
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Keywords: ., bookcentury1900, bookdecade1900, bookiddesignofthre, bookyear1907
