LOADING FOH M \\IHUIi 811 K A II AM) JIOMJ 



of the point to just the left <>f the point ui 



causes a decrease in shear by the amount of that load. 



Any fun h. -r movement of the system to the left Inoraistn 



the shear until another Inad passes from the right to the 



i the point im shear mu*t tru-rrforr be 



determined by trial and generally will occur for ihr first 



or second engine wheel just to the right of the given (mint 



For through bridges the maximum .-hear in any panel 



IF 

 is given when the weD-known criterion /'- if tstbfad, 



in which /' H the load in the pan,-!. IF the total load OH 

 the bridge and m the mind* r of equal panels in the span. 

 Sometimes two or even three positions of the load satisfy 

 r-it t-rinn. in which case the maximum shear is determined 

 by comupting the shear for all positions which ha 



tile !l. 



For maximui titrated load brought to a floor 



beam or trestle bent by two adjacent stringers or girders: 



nJF 



terion for position is P- 



n + m 



in which n and 



m are the lengths of the adjacent spans and P the load 

 on the span of length n, and IF the load on both spans. 



<j MOMENTS 



The bending moment, due to a certain number of 

 moving loads at any definite point in a girder either deek 



or through, is a maximum when ^"~JJ" * m *'hich P in 



the load on the 1, ft of the point, IF the total load on thr 

 structure and n the distance from the point to the left 



