What is point load?
Also called concentrated load, point load is what is applied to a very small area or a specific point inside a structure.
Normally, point loads are applied to nodes, in the case of reticular structures, and columns and beams. They can be applied perpendicularly or at an angle.
It is represented as acting on a single point, following the physical concept of a point particle.
What is the material point?
Also known as an ideal particle , a point particle is an idealization of classical physics according to which the size, shape, and structure of an object are irrelevant as long as its context allows. In terms of mass, this means that the object in question is thought of or modeled as an infinitesimal element, one that is infinitely small in volume.
For example, despite occupying a volume, elementary particles are usually considered point particles when put in relation to complex particles; this is because elementary particles have no known internal structure.
What unit of measurement is used to express point load?
Weight measurements, such as kilograms, kilonewtons, pounds, tons, etc. are used. Unlike distributed loads (which are expressed, for example, as kg/m), the acting area of the load is not expressed.
What effect does a point load have on a beam?
Point loads, among others, should be taken into account in the structural analysis, and the effect of loads on structural elements should be calculated as part of this. Given the linear structure of beams, the loads create flexion (i.e., a deformation perpendicular to the longitudinal axis), and this causes forces of traction and compression.
In the relationship between a beam and a point load, these elements, among others, come into play:
- Shear stress: resulting from all the vertical stresses applied to the beam.
- Support reaction: the forces generated by the supports of the structural element (the beam) receiving the point load.
- Bending moment: moment of force resulting from the distribution of stresses.
- Second moment of inertia (or area moment of inertia): the maximum deformation that an element can undergo due to flexion.
What methods are used to solve the problems related to point loads?
To perform the calculations related to the point loads, the following, among others, are used:
- Euler-Bernoulli beam theory: it theoretically simplifies the mechanics of deformable solids to achieve an approximate calculation of the stresses and deformations of the beams.
- Clapeyron’s theorem or theorem of three moments: proved at the beginning of the 19th century, it follows from the beam flexion theory and serves to solve some problems of hyperstatic flexion.
- Euler-Bernoulli theory: derived from the kinematic hypothesis of the same name and used to calculate stresses and displacements in beams.
- Timoshenko Theory: unlike the Euler-Bernoulli theory, it does not disregard the shear stress with respect to the bending moment, so it uses more complex equations applicable to the elastic curve of short beams.