38 



I 1\ I -HI U> SI KKSSI.S 



(21), (23), (24), (29), and (30) fm these dresses are of one 

 general form 



S - (0) M 4 - (fl) M, (27) 



where (r and H are the corresponding coefficients of M 4 



. 11. 



and .I/.-, in the preceding formulas. The rate of variation 

 of S as the load advances is 



2? = GW t - HW, = H (| W, - W,) . . (28) 



When any one of the above stresses is a maximum, the 

 c* 



(c* \ 



_ PT 4 Wt) passes through zero as a wheel ifi 



shifted from right to left of the salient point 3 in Figs. 

 7, 8, or 9. 



The preceding formulas for the live-load stresses are 

 summarized for convenient reference hi Art. 11 preceding 



