Essentials in the theory of framed structures . senta load of i lb., moving upon the beam AB. Draw the Hne QO,intersecting the verticals through A and B. Lay off QK = i lb.,draw the line OK, and let IJ represent the ordinate underthe load P. As P moves from B to A, the reaction at A in- Sec. II BRIDGES 131 creases uniformly from zero, when the load is at 5; to i lb.,when the load reaches A. Likewise the ordinate // increasesuniformly from zero at 0 to QK = 1 lb., at Q. Hence for anyposition of the load, the ordinate //, directly under the load,represents the reaction at A. The line OK is calle
Essentials in the theory of framed structures . senta load of i lb., moving upon the beam AB. Draw the Hne QO,intersecting the verticals through A and B. Lay off QK = i lb.,draw the line OK, and let IJ represent the ordinate underthe load P. As P moves from B to A, the reaction at A in- Sec. II BRIDGES 131 creases uniformly from zero, when the load is at 5; to i lb.,when the load reaches A. Likewise the ordinate // increasesuniformly from zero at 0 to QK = 1 lb., at Q. Hence for anyposition of the load, the ordinate //, directly under the load,represents the reaction at A. The line OK is called an influenceline for the reaction at A, since the ordinate // shows how thereaction at A varies or is influenced by any movement of theload. The influence line, thus drawn by the aid of the unit load,may be used for finding the reaction at A for a series of loadsin any position by multipljdng the ordinate under each loadby the ratio of its weight to i lb., and adding the Fig. 96 the ordinates for the loads Q and 5 are and 3000-
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectstructu, bookyear1922
