NOTATION. xvii 







R = reaction. 



= resultant of two or more forces or loads. 



RI, R2, etc. = reactions beginning at the left. 

 = rays in a force polygon. 



r = radius of gyration. 

 = radius of a circle. 



S = total shear or total shearing stress on a section. 



Px total shear at a distance x from the origin = S (pounds). 



5 = unit stress (pounds per square inch) . 



i = unit stress in the extreme upper fiber of a beam's cross sec- 

 tion. 



52 = unit stress in the extreme lower fiber of a beam's cross sec- 

 tion. 



s c = unit stress in compression. 



s s = unit stress in shear. 



s t unit stress in tension. 



s w = working unit stress. 



s u = ultimate strength in bending or modulus of rupture in cross- 

 breaking. 



t = thickness of web plate (inches). 



Ui, C/2> etc. = stresses in upper chord members. 



V = vertical reaction due to horizontal forces. 



V\, V2, etc. = stresses in vertical members. 



= vertical components of inclined reactions. 



i) = vertical distance perpendicular to the neutral axis. 

 = coordinate parallel to the principal axis VV. 



TI = distance of the extreme upper fiber of a beam's cross sec- 

 tion from the neutral axis. 



v 2 = distance of the extreme lower fiber of a beam's cross section 

 from the neutral axis. 



W = total uniform load. 



w = uniform load per unit of length (pounds per foot) . 

 = distance shown in figure. 



x = horizontal coordinate or distance lengthwise of a beam. 



x = distance of point of zero moment from the origin. 



y = vertical coordinate or deflection of the elastic line. 



2/i = deflection due to an instantaneously applied load. 



?/max = maximum deflection of the elastic line. 



z = coordinate parallel to the principal axis ZZ. 



a = angle shown in Fig. 



/? = angle shown in Fig. 



