Punktlast

Punktlast, or point load, is a force applied to a structure at a single, well-defined location. It is an idealization used in structural and mechanical engineering to simplify the analysis of loads that act over small contact areas relative to the overall size of the structure.

In mathematical terms, a point load at position x0 with magnitude F can be represented in one dimension as F multiplied by a Dirac delta function δ(x − x0). In practical engineering analysis and computer models, the load is applied as a nodal force at a node or as a concentrated force at a specific point. The direction of the load is given by its vector components.

Point loads occur in many situations, such as a person standing on a beam, the weight of a compact machine, a hammer strike, or a concentrated pressure from a pedestal. They are often used to approximate real loads that are small in contact area or vary rapidly over a short distance.

On a structural member, a point load creates a jump in the shear force diagram at the application point, while the bending moment diagram remains continuous but experiences a change in slope there. For example, on a simply supported beam of length L with a point load P at a from the left end, the reactions are RA = P(L − a)/L and RB = Pa/L.

Limitations include the fact that many real loads are distributed rather than truly concentrated. Point loads are therefore an approximation, and local stress concentrations, dynamic effects, and load paths must be considered in design and analysis. The term Punktlast is commonly used in German engineering contexts; in English, the terms point load or concentrated load are used.