A beam in which bending stress developed is constant and is equal to the allowable stress, is called a beam of uniform strength. A beam of uniform strength has, at every cross-section, same bending stress.
Beam of uniform strength can be achieved by:
1. Keeping the width uniform and varying the depth,
2 Keeping the depth uniform and varying the width,
3. Varying the width and depth both.
The common method of obtaining the beam of uniform strength is by keeping the width uniform and varying the depth.