A load may be defined as the combined effect of external forces acting on a body. The loads may be classified as:
1- Dead loads
2- Live or fluctuating loads
3- Inertia loads or forces
4- Centrifugal loads or forces.
The other way of classification is
1- Tensile loads
2- Compressive loads
3- Torsional or twisting loads
4- Bending loads
5- Shearing loads
The load may also be a ‘point’ (or concentrated) or distributed.
Point load
A point load or concentrated load is one which is considered to act at a point. In actual practice, the load has to be distributed over a small area, because, such small knife-edge contacts are generally neither possible nor desirable.
Distributed load
A distributed load is one which is distributed or spread in some manner over the length of the beam. If the spread is uniform. (i.e., at the uniform rate, say w kN or N/metre run) it is said to be uniformly distributed the load and is abbreviated as u.d.l. If the spread is not at a uniform rate, it is said to be non-uniformly distributed load. Triangular and trapezoidal distributed loads fall under this category.
