The cross section of a narrow-gage railway bridge is shown in part (a) of the figure. The bridge is constructed with longitudinal steel girders that support the wood cross ties. The girders are restrained against ateral buckling by diagonal bracing, as indicated by the dashed lines. The spacing of the girders is s1 = 45 in. and the spacing of the rails is 82 = 30 in. The load transmitted by each rail to a single tie is P = 1,400 lb. The cross section of a tie, shown in part (b) of the figure, nas width b = 5.0 in. and depth d. Steel rail Wood tie Steel girder (b)
The cross section of a narrow-gage railway bridge is shown in part (a) of the figure. The bridge is constructed with longitudinal steel girders that support the wood cross ties. The girders are restrained against lateral buckling by diagonal bracing, as indicated by the dashed lines. The spacing of the girders is s1 = 45 in. and the spacing of the rails is s2 = 30 in. The load transmitted by each rail to a single tie is P = 1,400 lb. The cross section of a tie, shown in part (b) of the figure, has width b = 5.0 in. and depth d. Steel rail Wood tie Steel girder (b) (a) Determine the minimum value of d based upon an allowable bending stress of 1,525 psi in the wood tie. (Disregard the weight of the tie itself.). Round your answer to one decimal place. dmin in.
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