En cada apartado tienes el audio para oir la pronunciación. Al final de la página tienes el vocabulario esencial para el tema de estructuras.
Tienes el tema en Español en el siguiente enlace: Estructuras y Tipos de Estructuras
What is a Structure?
"A structure is a set of elements united with each other, with the mission of supporting the forces acting on them."
As we see, Structures are built to support forces.
Force = Everything that can deform a body (static effect) or modify its
state of rest or movement (dynamic effect). The forces that act on a
structure are called Loads.
Main Elements of a Structure
- Beam: Horizontal element in the structure.
- Pillar: Vertical element in the structure. It is
called a column if its shape is round.
- Joist: Small beam that is supported between two
beams to form the ceiling or floor.
- Foundations: It is the element of a structure
which is connected with the ground, and transfers the loads from the structure
to the ground.
Types of Loads
- Fixed Loads: they are what do not change on the
structure. They always have the same value. For example the weight of the
structure and any element that are always in the structure.
- Variable loads: those that can change
on the structure with the over time. Examples: air force, people's weight, snow, etc.
An effort is the internal force that the elements
of a structure experience when they are subjected to external forces. The elements of
a structure must withstand these stresses or efforts without breaking or deforming.
Types of Efforts or Stresses
There are main 5types of
Efforts or Stresses.
- Traction Effort: An element is
subjected to a traction effort, when the forces acting on it, they try to
stretch it. An example would be the cable of a crane. Watch out, They will try to
stretch it, but in an element of a structure, the forces should never get
it, at least visually (with the naked eye). This should happen
for all the efforts that we are going to explain. The forces will try it but
they must not get it.
- Compression Effort: An element is
subjected to a compressive effort, when the forces acting on it, they tend or
try to compress it. Example the legs of a chair.
- Flexing Effort or Bending effort: An
element is subjected to a bending stress, when the forces acting on it, they
try to bend it. An example it's the
board of a table.
- Torsion Effort: An element is subjected to a
torsion effort, when the forces acting on it, they try to twist it. Example: a key opening a
- Cutting Effort or Sliding Effort: An
element is subjected to a cutting effort, when the forces acting on it, they try to cut
it. Example: a scissor.
Conditions of the Structures
1ª) The structure must be rigid: means
that it does not deform when it is subjected to external forces. we get it
triangulating, or what is the same, it is built with the shape of
a triangle or with its parts in triangle shape.
2ª) The structure must be stable: means that the
structure does not overturn when it is subjected to external forces. You can get
it by making the base wider, or putting up braces or cables.
3ª) Must be resistant: means that each element of the structure is
able to withstand the stresses or forces to which the element is going to be subjected.
The size and shape of each element is what will make them to withstand the
efforts and the forces.
The shape of the beams is called Profile. Here you
have some examples of the profiles of the different types of metal beams
Types of Structures
They are formed by bars united together in the form of a triangle. For
example construction cranes.
They are the structures that are used in our buildings today. They are
structures built with bars and beams of reinforced concrete (with steel bars
Cables are used for hanging part of the structure. The cables
are called braces. For example the hanging bridges.
They are formed by laminae. An example with the body of the cars, the
housings of the televisions, the mobiles, etc.
They are structures that they are constructed by accumulating material,
without leaving gaps between them. An example is the pyramids.
They are structures that have arches and vaults. The arches allow to
increase the voids in the structure and the vaults are arches one after another. They were used a lot in churches, cathedrals and bridges.
1) What is a structure?
2) What is a force?
3) What is a load?
4) What types of loads do structures have?
5) What is an effort?
6ª) Make a drawing with arrows that represents the types of efforts to
which the elements of a structure can be subjected.
7) What are the 3 conditions that a structure must have? How do you get
8) Types of structures and an example of each type.