;ARS. 





105. Maximum Live Load Shears in a Continuous 

 Beam of Three Spans. For a maximum positive shear in one of 

 the outer spans of Fig. 

 123, the loading should be 

 as shown, because Fig. 

 112 shows that a load in 

 either end span will pro- Fig. 123. 



duce a positive reaction at both ends. The first span is not fullii 

 loaded, because a load to the left of the section will increase /,', 

 less than it will decrease the shear. A load in the middle SP;LM 

 will evidently produce negative reactions at both ends. 



The loading for 

 maximum negative 

 shear at any section in 

 an outer span, must be 

 the complement of that 

 for maximum positive 



-Qmax. 



Fig. 124. 



shear or as shown in Fig. 124. 



The loading for maximum shear in the middle span is easily 

 determined but is seldom needed. 



106. flaximum Live Load Moment in a Continuous Beam 

 of Two Spans. In a two span continuous beam, any load in the 

 second span will produce a 

 negative moment in the first 

 span, at any section (Fig. Ill 

 reversed). A load in the 

 first span may produce either 

 a positive or a negative mo- 

 ment, depending upon the 

 location of the load and the 

 section; but since the point 

 of contra-flexure lies between 



x = - I and x = l, the mo- 

 ment is always positive for 

 a load anywhere in the first Fig. 126. 



span, if x < ^ 1; therefore, for x < ^ I, the loadings should be as 

 pbown in Figs. 125 and 126. 



