Art. 153. STRESSES IN A PRATT TRUSS FROM WHEEL LOADS. 303 



Post 7 2 . Wheel 3 at Joint 4, 



F 2 =shear = 81.4 (+) L.L. 



= 1.31X29.15= 38.2 (+) D. L. 



119.6 ( + ) Total. 

 Post 7 3 . Wheel 3 at joint 3, 



F 3 =shear =46.2 (+) L. L. 



=0.31X29.15= 9.0 (+) D. L. 



55.2 (+) Total. 



For the hip-vertical, V lf we must apply the criterion for 

 maximum floor beam concentration, equation (91) ; Art. 152. 



By inspection it is evident that wheel 12 or 13 at joint 6 will 

 give a maximum load at that point. 



Wheel 12 at joint 6, G l =43, P =20, G 2 =53. 



If P be counted with G l it makes the first panel load the 

 greater, and if it be counted with G 2 it makes the second panel 

 load the greater, therefore it satisfies the criterion. 



Wheel 13 at joint 6, G^ =50, P =20, G 2 =46. 

 By the same reasoning this also satisfies the criterion. 

 Wheel 11 at joint 6, G t =36, P=20, G 2 =60. 

 This does not satisfy the criterion. 

 Wheel 14 at joint 6, G t =60, P =20, G 2 =39. 



This does not satisfy the criterion. 



With wheel 12 at joint 6, the portions of the load in the 

 two adjacent panels going to the floor beam 6, are found by 

 moments at joints 5 and 7. 



p ane l 6 -7 ^..'8X1 + 10X9+20X17 =2Q14 



Panel 5-6 ^.18X3+20X12+20X17+20X22,^^ 



Vi =68.28 (-) L.L. 



