SIMPLE TRUSSES 



this becomes 



13 



. (34) 



An equivalent criterion is 



l-s 



AB 



-I& ' < 35 > 



This criterion holds good for any influence diagram 

 which is triangular in shape. 



Top Chord of Curved-chord Simple Truss. The construc- 

 tion of the influence diagram follows the same general rule 



Tan 0i=l. Tan 2= r-. Tan 61 = 



FIG. 6. 



as in the previous case. The points A and F, Fig. 6 coincide, 

 while E is on the right line connecting D and A since the 

 line EF coincides with this line. 

 For wheel loads the criterion is 



Wi+W 2 



W 



. . (36) 



where W = the total load on the span. 



