Theorem 1 of Moment Area Method

Theorem 1 is stated as follows :

” The change in slope between tangents drawn to the elastic curve at any two points A and B is equal to the product of 1/EI and the area of the moment diagram between these two points.”

Mathematically, it can be written as

For simplification we can say first draw the elastic curve diagram of the beam, then draw tangents at those two points for which change in slope has to be determined ( in the above diagram these points are A and B ) . Then Θab is the change in slope between tangents drawn to the elastic curve at these two points A and B.