20 



INFLUENCE DIAGRAMS 



The criterion for wheel loads producing maximum 

 moment is 



W W 2 +W 2 ' 



(50) 



Lower Segment of Diagonal in Sub-hanger Truss. As in 

 the case of the upper segment in the sub-strut truss this 

 member is a part of the diagonal of the main truss and has 



K S 



Tan 0i = 1 . Tan 62 = S -. Tan Ot = 4 



FIG. 12. 



its stress only. Taking the horizontal projection of UL" 

 as the length of the cut stringer the influence diagram 

 DEFBD, Fig. 12, is constructed according to the general 

 rule. The distances d f and x' are found in the usual manner. 

 The criterion for wheel loads producing maximum 

 moment is 



W W 2 +W 2 ' 

 I = d' 



(51) 



