148 



KANSAS UNIVERSITY QUARTERLY. 



Solving this equation we find 



Placing the value of z in (16) eqnal to that in (17) and simplifying 

 we have 



^°]xj -7°i-Ti +^°"n-f -^'^\i-\ -441x1 +3 



=-0 (t8) 



One root of (18) is --^=.^16. Substituting this value of— in 



(17) we have z=r. 724I 



Substituting these values of x and z in (5) we have 



(Mr)max=:— .044PI (19) 



Hence the maximum moment occurs under the load; is positive, 

 and equals .086PI. 



FIG. II. 



Case II. The moving load uniformly distributed per horizontal 

 foot. 



Let the notation be as in case one as far as applicable with w equal 

 to the intensity of loading and x the portion of the span covered with 

 the load, measured from A. 



Proceeding as in case one we find that 



wx2 \ - X 



Vn= — 7— and V=wx a i 1- 



2I ( 2I 



both of which are independent of the shape of the rib. 



The moment about any point of the rib to the right of the load is 



( x I ' 

 Mr=VjZ — - z r wx; — Hy (20) 



The moment about any point of the rib under the load is 



Mi= V J z — w- — - — Hy 



(21) 



