Which part of the beam has more Bending Moment?
It depends on the type of beam, support conditions and external loads acting on the beam.
For a simply supported beam, maximum bending moment is located at the point where shear is zero. This occurs because shear is the mathematical derivative of bending moment, and the maximum bending moment occurs when its derivative (i.e. shear) is zero.
For beams with fixed or partially restrained end supports, or continuity over an internal support, the bending moment diagram of the simply supported beam will be transformed according to the level of bending moment attracted. If you estimate the bending moment at these supports, you can transform the simply supported bending moment diagram accordingly to get an idea of the location of maximum bending.
Following example would describe the above:
- A simply supported beam subjected to uniformly distributed load will have maximum bending moment at the centre.
- Simply supported beam of two continuous spans subjected to uniformly distributed load would have maximum sagging moment at the span centre and maximum hogging moment at the supports.
- A single span beam with fixed supports would have maximum hogging moment at supports and maximum sagging moment at the span centre.
- A cantilever beam subjected to uniformly distributed load would have maximum bending moment at the fixed support.
- A simply supported beam subjected to two point loads at 1/3 span would have the maximum moments at the place where the concentrated load are acting.