Van Nostrand's engineering magazine . of thepolygon of forces, considering, for thesake of simplicity, the imaginary case ofan articulated structure. The lattice,moreover, is hypothetically reduced tothe lines of Fig. 4, by omitting as wellthe foot of the straight uprights, replacedby the corresponding curved or polyg-onal stay, as in each row of bracing, thatof the two diagonals which, exposed toa wind from the left, would be strainedin compression, and are considered to betoo flexible to offer an effectual resistancein this way. The external forces applied to thevarious summits produce the f
Van Nostrand's engineering magazine . of thepolygon of forces, considering, for thesake of simplicity, the imaginary case ofan articulated structure. The lattice,moreover, is hypothetically reduced tothe lines of Fig. 4, by omitting as wellthe foot of the straight uprights, replacedby the corresponding curved or polyg-onal stay, as in each row of bracing, thatof the two diagonals which, exposed toa wind from the left, would be strainedin compression, and are considered to betoo flexible to offer an effectual resistancein this way. The external forces applied to thevarious summits produce the followinghorizontal components. At the summitA the whole force of the wind against thebeams and the train is brought to bear,namely, a force of tons obtained bydividing the moment, 7,331, by theheight, 183 feet, of the point A above thebase. The pressure against the half pier amounts to about 2 tons acting at eachof the points B, G, H, . . I, situatedon the side which the wind strikes. Theweights or vertical components are:—. Bars under compression. tension. 5JJT5- ScaleTheoretical Structure of the Pier. tons at A, due to the loaded road-way ; the same weight at B increased bya portion of the pier, amounting al-together to tons; lastly, in each of LAA1& THE RESISTANCE OF VIADUCTS TO SUDDEN GUSTS OF WIND. 221 the points G, H, . . I and C, D, . . E, a vertical force of 0 tons. The re-actions in equilibrium developed by thebase of support arc : at K. the tension ofanchorage, amounting to tons as in projection all the wind pressures, isequal to tons. The resultants at the different pointsconsequently assume oblique or verticaldirections. The oblique resultants are :
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectenginee, bookyear1879
