68 NOTES ON !' I. \TE-GIRDEK DlSKlN 



Now suppose the loading to advance a >mall distance 



to the left of dx, then 6-6, x-x+dx, and c = c+dj-, ami 



the hriidini; moment 



(Wc+dx) A 

 -P6 as /2i- 1 -tbia 



neglecting terms containing dx 2 , 



TFc TFcx TTcdx TFdx JFxdx 



M ! ^~ ~r ~r 



Subtracting () from (^9) 



TFdx 



dm __ W ^ 

 = " 



dx 2 I I ' 



and for a maximum this must rqual 0. 

 W Wx We 



~T"T" 



-. ) +j:+c = 



ami c= 7 "" c 



which establishes the criterion as state* 1. 



PROBLEMS 



13<7. Compute the maximum bending moment for a deck plate 

 girder of 18' effective span length for Cooper's E M . Assume the girder 

 to carry one-half the loading. 



IM. Compute tin- maximum IxMiding moment for a 2-V spun, MUM 

 loading as 13a. 



13c. Compute the maximum center moment for a 25' span, same 

 loading as 13a. 



