BENDING MOMENT 



If R 4 and R 2 are the reactions at the supports 

 30R, = 5 x 25 + 10 x 15 -f 7-5 x 5 



R 2 = 10^ tons 



287 



Then 



Also 



7-5 x 25 + 10 x 15 + 5 x 5 



FIG. 95. 



(1) Considering a section situated between A and B at a dis- 

 tance x feet from the end. The forces acting to the right of this 



section are : 



5 



(a) R 2 = 10 tons vertically upwards at a distance x ft. 



x x 



(b) - tons acting vertically downwards at a distance - ft. from 

 - 



the section. 



125 x z 

 Bending moment = -x - ft. tons, and this expression can 



1 - 4 



only be used when x has values between and 10 ft. 



(2) Considering a section situated between B and C at a dis- 

 tance x feet from the end. The forces acting to the right of this 



section are : 



5 



(a) R;j = 10 tons acting vertically upwards at a distance x ft. 

 12 



(6) 5 tons acting vertically downwards at a distance (x 5) ft. 



(c) (x 10) tons acting vertically downwards at a distance 



125 1 



Bending moment = - T x 5(x 5) - (x 10) 2 ft. tons and 



I '- a 



this expression can only be used when x has values between 

 10 ft. and 20 ft. 



