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12. Simple Bending Moment and Shear Force Diagrams Let us apply a Concentrated Load on a simply supported beam and see how the beam behaves Flash Now let us cut the beam in to three imaginary parts and examine the internal response of the beam It is obvious that none of the 3 parts are in rotational equilibrium, for example if we take the element of the beam it will rotate as below: To establish rotational equilibrium, the beam has to develop internal moments as shown below> Flash These internal moments which establish rotational equilibrium for the elements of the beam are the Bending Moments in the Beam. One objective of this chapter is to determine the internal Bending Moment along the length of the beam for various simple loadings on the beam. Every beam, in a building , bridge or any other construction is subjected to the internal Bending moment. And one of the objectives of design is to make the beam adequate to sustain the expected Bending Moments on it. Shear in Beams Let us load a simply supported beam Flash The above phenomenon is called shear in Beams. In order to satisfy vertical equilibrium the beam should develop internal forces as shown below Putting the above ideas of Bending Moment and Shear together we get the following behavior Flash