xvi NOTATION. 



e = eccentricity of the cente- of gravity of a train with regard 



to the center line of the bridge. 

 = distance shown in the figure. 

 H = horizontal reaction. 



h = height of a rectangular cross section. 



= depth of the web of a girder. 



/ = moment of inertia of an area about its neutral axis. 

 / Q = moment of inertia of an area about an axis QQ parallel to 



the neutral axis. 



7 V =: moment of inertia about the principal axis VV. 

 l z = moment of inertia about the principal axis ZZ. 

 k = in continuous beams, a fraction less than unity which mul- 

 tiplied by the span length gives the distance of a load 

 from a support. 



fc = that value of k which corresponds with x . 

 ki = distance center to center of bearings, on the pin, at the top 



of the post. 

 ^ 2 = distance center tc center of bearings, on the pin, at the 



bottom of the post. 

 L = total length. 



LI, L 2 , L 3 , etc. = stresses in lower chord members. 

 L. L. = live load or live load stress. 

 h, h, etc. = partial lengths of L. 

 J/= moment at any point or bending moment (foot pounds or 



inch pounds). 



Afi, M> 2 , A/ a , etc. = moment at points 1, 2, a, etc. 

 MR = moment of resistance of a beam. 

 M a = statical moment of an area. 

 Af x = moment at a distance x from the origin = M. 

 ra = ratio of longitudinal to transverse deformation = reciprocal 

 of Poisson's ratio. 



A 7 = number of panels. 



n = a factor less than unity which multiplied by I gives the span 

 length nl. 



P = concentrated load or force or panel load. 



--Pi, ^2, ^3, etc. = concentrated loads from left to right. 



P i = instantaneously applied load. 



p = panel length. 



t q= proportion of dead load at unloaded chord. 



