. Stresses in railway structures on curves . (b - 2e), in which ? is the shear or moment in each stringer ofa bridge on straight track, b is the spacing of stringers and e isthe average eccentricity of the track (the curve of center of grav-ity of train) with reference to the axis of the stringers. In orderto equalize the shears or moments in both stringers, we must haveb + 2e + 2qh = b - 2e 94 from which we obtain 6 = - * that is, each pair of stringers should be so located that the track(the curve of the center of gravity of train) will have an averageeccentricity of —^ qh with referenc
. Stresses in railway structures on curves . (b - 2e), in which ? is the shear or moment in each stringer ofa bridge on straight track, b is the spacing of stringers and e isthe average eccentricity of the track (the curve of center of grav-ity of train) with reference to the axis of the stringers. In orderto equalize the shears or moments in both stringers, we must haveb + 2e + 2qh = b - 2e 94 from which we obtain 6 = - * that is, each pair of stringers should be so located that the track(the curve of the center of gravity of train) will have an averageeccentricity of —^ qh with reference to the axis of each pair ofstringers. In the example being investigatedq = .1315 h = -• e = qh = - x .1315 x = we have already determined the net eccentricitiesof the track at the panel points with reference to the center lineof the bridge, the location of the stringers in each panel can beeasily found. Fig. 39 shows the locations of the axes of the stringers that will give an average eccentricity of Truss Fig. 39. 3 Using e = , we have l(b + 2e + £qh) = -1,( - 2 x .4274 + ) = l(b -2e) = -=1^( + 2 x .4274) = 95 For a bridge on straight track, each stringer has a shearof 71,000 lbs. and a bending moment of 381,500 For thepresent case, the maximum shear will be 71,000 x = 79,100 the maximum moment will be 381,300 x = 424,800 lateral shear and moment are as before 9340 lbs. and50,100 respectively. Art. 16^ Stresses in Floor beams. In a bridge on straight trac^ with central loading, themaximum shear on a floor beam is equal to the maximum panel load oneither the outer or inner truss; and the maximum bending moment onthe floor beam i6 equal to the product of this panel load multipliedby the distance from the center of either truss to the nearer stringser. If the panel lengths are equal, these stresses will be the samefor all floor beams. When the b
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