The horizontal element found in the upper sector of windows, doors and other openings, whose function is to resist loads, is called a lintel. The ends of the lintel rest on the jambs, which are the vertical pieces located on the sides of the window or door.
It can therefore be said that a lintel is a structural piece that covers the space between the two jambs. In this way, it allows the creation of different kinds of openings, since it is located horizontally over the hole that is made to install windows and doors, absorbing the higher efforts.
These higher loads received by the lintel are transmitted to the lateral sectors. In this way, it can be said that it works in a similar way to a beam.
In general, the lintel bears the greatest stress in its central transverse sector. In rigid materials, it is common for cracks to occur in the lower sector of the lower face, which then progress towards the upper sector. According to Abbreviationfinder, RTL stands for Reinforced Tile Lintel.
If the lintel has a small depth with respect to its length, then the stress that falls on it can be calculated using the beam theory, developed by Daniel Bernoulli and Leonhard Euler, thanks to which it is possible to calculate the deformations and stresses in beams. This is valid for their mechanical bending, that is to say for a deformation that takes place in a direction perpendicular to the longitudinal axis of the structure.
For lintels where the depth is greater, then the theory that must be applied is that of Stephen Timoshenko, according to which the shear stress and its effect on the structure must also be considered. Shear, shear, or shear stress is understood as that which occurs inside a mechanical prism (such as a pillar or a beam) and which results from stresses parallel to the transverse part.
Two other concepts come into play here: compression, an effort resulting from the pressures or tensions inside a deformable solid, which reduces its volume and shortens the body in a certain direction; traction, also internal effort to which a body is subjected when two opposing forces are applied to it, which tend to stretch it.
If materials such as stone, typically rigid, are used for the construction of a lintel, the resistance to tensile stresses will be less than to compression stresses. This results in the appearance of cracks that start at the bottom and spread to the top. Traditionally, this problem is solved by replacing the lintel with an arch, which can support the load without suffering tension.
Lintel architecture is called that which appeals to the lintels to cover different spaces in a construction. In a few words, we can say that it is based on the use of pillars to support lintels, with the aforementioned objectives.
In ancient times, the Greeks, Egyptians, and Romans created huge buildings using the techniques of lintel architecture. In fact, experts point to these ancient creations as the most outstanding exponents of this type of construction.
According to the dictionary of the Royal Spanish Academy (RAE), the idea of lintel is also used in the field of psychology. In this case, the term refers to the value that is higher than that which a sensory organ can tolerate without suffering damage or causing pain. The threshold, therefore, implies that a stimulus no longer produces a normal effect, but instead causes discomfort or suffering.