4.18 : Distributed Loads

Distributed loads are a common type of load that engineers and scientists encounter in various practical situations. Distributed loads often refer to a type of load spread over a surface or a structure and can be modeled as continuous force per unit area.

For example, consider a bookshelf filled with books stacked vertically adjacent to each other. The weight of the books is evenly distributed over the length of the shelf. As a result, the pressure at different locations on the surface of the shelf corresponds to the applied load and is measured in Newtons per square meter, or Pascals.

In terms of another application, consider a hydroelectric dam, for which the submerged surface is modeled as a rectangular plate. The force exerted on a small element of the plate of length dx can be expressed as the distributed load, given by wdx, where "w"is the force per unit area. The total load applied to the plate can be determined by integrating the force exerted on each small element. The magnitude of the resultant force exerted on the plate is proportional to the area under the load curve, and its line of action passes through the centroid of the area. This point is known as the center of pressure. The center of pressure is essential in designing structures that can withstand external forces.

Examples of distributed loads include snow loads on the roof of a building, wind loads acting on a structure, or even the weight of a car on a bridge. Understanding distributed loads is crucial for designing safe, robust structures that can withstand external forces.