\cTKS ON i'i.\n:-(,n;i)i:i; DESIGN 



Tin- p-nrral equation fur moment for t\\o loads spaced 

 5' apart i- 



250,000+lOdi 



Af-A(J-6-x) 



-, 



- I 



-250,000 X 100,000* -750,000^ -lOO.OOOj ' 



,100,000 -^-^f55-o. ,. *-!. 



-\ 



FIG. 146. 



Substituting for x its vlaue, we have for 

 j:(),000 



+ 100,00o(|-3.75) r 

 Vf / j _ .^ - . 



= 250,OOOZ -125,000 + 



By plotting the curves of moments for different lengths 

 of spans we see that somewhere between 8' and 9' one 

 load and two loads produce the same moment. 



To find this point exactly we make the equations for 

 moments simultaneous and solve to find the value of I 

 for which the moments are equal. 



250,OOOZ - 125,000 + 



For this case 



\\hmcef -8.54'. 



The next step is to get the general equation of moments 

 for three loads. Make it simultaneous with that for two 



