There are a few very important concepts of bending. there are indeed two differnt kinds of bending,"+ve bending moment" and "-ve bending moment" +ve bending is when the sum of moments to the left is clockwise or when the sum of moments to the right is anticlockwise.-ve bending is when the sum of moments to the left is anti-clockwise or when the sum of moments to the right is clockwise. bending accurs when an object becomes curved due to a curling force. there are three main forces applying force. one force in the center and the other two on the out side points that are holding the object that is bending.

+ve bending moment

-ve bending moment

Henry