22 LIVE-LOAD STRESSES 



Absolute Maximum Bending Moment. 



Shift t04 according to centre of gravity rule, and tin MI 

 recompute the value of M under this wheel by formula (10). 

 Note that new values for /i, k, and M* must be determined. 



By formula (13a), when w 4 is at the centre, 



M, 2838.75 



= TF, = 145 



Therefore for absolute maximum bending moment under 

 90' (X) 1 T "is 



u> 4 , shift loading to left - -^~ = OVJ 1 . 



The new values of li, l, and A/ 3 are 



Zi = 20.00 - 0.21 = 19.79 

 J, = 20.00 + 0.21 = 20.21 

 M, = 2838.75 + .21(145) = 2869.2 



The absolute maximum bending moment = 

 M = M * + Ml " M * 



= ^~- (2869.2) + - 600 = 819.54 Kip feet. 



It appears, therefore, that the absolute maximum bend- 

 ing moment is .17 Kip feet greater than the maximum cen- 

 tre moment. The difference is not great in this particular 

 case, as the required shift of the loading is comparatively 

 small. The position of loading for absolute maximum bend- 

 ing moment agrees with Table 4, and its value agrees with 

 Table 7. 



