CHAPTER IX. 



MOVING LOADS ON BEAMS. 



Uniform Moving Loads. Let the beam in Fig. 39 be loaded with 

 a uniform load of p Ibs. per lineal foot, which can be moved on or off 

 the beam. 



Uniform Moving Load 

 = p Ibs- per lin-fr- 



(a) Maximum Positive Shear 

 Load moving off To the right 



(b) 



Maximum Negative Shear 

 Load moving off to the left 



FIG. 39. 



To find the position of the moving load that will produce a max- 

 imum moment at a point a distance a from the left support, proceed 

 as follows : Let the end of the uniform load be at a -distance x from 

 the left reaction. Then taking moments about R 2 we have 



and the moment at the point whose abscissa is a will be 



P = ( -^^ 2 ^P- ( ^-^ P 



2L 



(15) 



(16) 



