46 



INFLUENCE DIAGRAMS 



Diagonal of Anchor Span. As shown in Fig. 32, the 

 diagonal (7aI/2, has its center of moments at the inter- 

 section of the two cut chords U^Uz and Z^Z/a. For loads 

 in this span the moment influence diagram is the base 

 diagram as shown by heavy lined shaded figure in Fig. 32. 



Cantilever Suspended Spaa 



FIG. 32. 



The criterion for wheel loads in this span which produce 

 the maximum moment is 



(74) 



For loads in the cantilever span, M L =0, M R = 

 =0, and 



. . . (75) 



Since r- is the tangent of the angle ^3 the influence diagram 

 for M, is the shaded area BKL. 



