Before constructing civil works, it is important to consider different structural aspects. For example, a determining factor in construction is wind load, which is subject to certain factors such as the structure or cladding.
What is wind??
Wind is the movement of air that is present in the atmosphere, especially in the troposphere, produced by natural causes.
In design, wind is known as an accidental action from the point of view of the load combinations in which it intervenes and the load factors that must be adopted.
When we're not construction experts, it's natural to wonder why wind can affect buildings. However, when considering wind in civil engineering projects, engineers are referring to the forces exerted by the kinetic energy of a moving air mass, which directly impacts a building's structure, components, and cladding.
What is a structure?
All types of structures are designed to withstand their own weight, external forces, and the functional requirements for which they were conceived. These forces include moments, thermal loads, and so on. This is what we call a structure.
Therefore, every structure has a negative or zero number of degrees of freedom, so the only displacements that can affect it are the result of internal deformations.
How does wind affect structures?
It is important to consider various factors to prevent the structure of any building from deforming. Among these is wind pressure. This is proportional to the square of the wind speed, especially on exposed surfaces.
Because wind speed is variable, a building assumes a deformed position at a constant speed and vibrates from this position due to turbulence. Understanding this requires an analytical procedure that evaluates the effects of wind force. In fact, it can be argued that wind forces can be a determining factor in the design.
What are wind loads?
Wind loads are the forces exerted by the kinetic energy of a moving air mass, assuming it originates from any horizontal direction. For this reason, the structure, components, and cladding must be designed to withstand wind-induced sliding, uplift, or overturning.
The analytical process for wind loads depends on the structure's location, height, exposed area, and position. For example, in open countryside with very low vegetation, the wind maintains a very high speed even very close to the surface, while in cities with tall buildings, the speed decreases rapidly.
Therefore, we can conclude that when the free flow of air is obstructed by a fixed object, it has to deviate to go around it. This is how pressure is generated on the object.
What type of pressure does the wind exert on a building?
Wind pressure is a minimum value derived from the critical wind speed and calculated according to several coefficients, for example, the height of the building, gusts, geometry and orientation of the structure are taken into account.
Therefore, it can be said that wind can exert positive pressure in a normal, horizontal direction on roof surfaces with an inclination greater than 30°. Likewise, it can also exert negative pressure on leeward and windward surfaces with an inclination less than 30°.
All complex, flexible, and unusual structures must undergo various tests or investigations to determine how they respond to applied pressure. These tests are essential for safe construction.
Because building construction is a complex procedure, they need the support of experts in foundations and civil works such as warehouses, ships or civil engineering projects.
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