7 



DEFLECTION OF BEAMS 



though requiring considerable labor in preparing the diagrams. The 

 solution will first be explained and a proof given later : 



Draw Bridge With Three Supports. In Fig. 9 a continuous 

 beam with spans L-, and L 2 is loaded with concentrated moving loads 

 represented by P 1 and P 2 , as in (a). 



L 2 with a bend- 



In (b) load a simple beam having a span L 

 ing-moment polygon due to the reaction R. z (the value of R 2 is unknown, 

 and any convenient load will do). 



Divide the bending-moment diagram into segments, construct a 

 force polygon as in (d) and draw an equilibrium polygon as in (c) 



