The importance of the the structural framework of a building in terms of structural stability and strength. It might seem that stress calculations should focus solely on beams and columns, but nothing could be further from the truth. The forged, in addition to being the horizontal planes that make life in buildings possible, they play a key role: distribute structural loads toward the various porticos that make up the structure of a conventional building.
Structural Loads on a Building
But what are the loads on structures? These are all the external forces acting on a building’s structural elements. They can be static, such as the dead weight of materials and finishes, or dynamic, such as those caused by wind, human use, snow, or even heavy furniture.
This gives us a glimpse of what the distributed loads on the structural elements of a building. Specifically, we are referring to those loads that are applied across the entire length or area of a structural element (wind, snow, floor slabs, etc.), as opposed to the spot shipments, such as a vehicle, a safe, or an item that is small in size but very heavy.
Types of Distributed Loads
- Linear distributed loads: These are loads that are distributed evenly in a strictly linear manner; this means that they are generally measured in N/m.
- Surface distributed loads: These are loads that are distributed evenly across the length and width of a surface; therefore, they are measured in N/m.2
Logic for Calculating Distributed Loads
As we've already mentioned, the the structural framework of a building It is the best example of an element designed to distribute loads. For this reason, we use it as a basis for understanding the method for calculating distributed loads. To learn more about the composition and structural behavior of floor slabs and their variants, we recommend reading our post on types of floor slabs.
We must start from the premise that a floor slab is composed of a series of “joists”, distributed evenly and supported by two frames (beams and columns), and a surface layer that connects all the joists. The joists are what actually distribute the loads to the frames.
Area of Influence
Provided that this condition is met, the calculation can be simplified by assuming that the portal beams receive loads from the midpoint of the perpendicular joist resting on them, and that the beam then transfers these loads to the columns. The area formed by the midpoint of each joist and the portal frame beam is known as “area of influence”.
Consequently, all loads acting on the floor slab within the area of influence are considered surface loads, which, for calculation purposes, are converted into a linear load on the frame beam by multiplying the surface load by the width of the area of influence.
For distributed loads, the logic is fairly straightforward, but to gain a deeper understanding of the methodologies for calculating and sizing structural elements, we recommend Structuralia’s Master’s Program in Structural Analysis, which covers the latest software tools for the comprehensive analysis of structures.
By taking into account the true significance of the loads distributed across a floor slab and applying this simple logic, it is possible to prevent cracks in the various floor finishes—and even in the floor slab itself—caused by differences in load distribution; provided, of course, that the other structural elements are correctly sized and designed.
