Efforts

The structures are intended to withstand external loads without deforming or breaking. As a result of these external loads, structures support internal forces called stresses.

Loads and efforts

Burden
It is an external force that acts on a structure. It can be a weight, a push, thermal expansion, etc.
Effort
Tension or internal force that a structure supports as a result of external loads.

For example, a person sitting in a chair is a burden on the chair. Due to this load, the legs of the chair support a compression force.

There are 5 different efforts. Each one is explained below.

Traction

Tensile stress tends to stretch the structure:

_images/esfuerzo-traccion.png

Examples of elements that support this effort are:

  • Chains of a swing.
  • Crane cable.

Compression

The compressive stress tends to compress the structure:

_images/esfuerzo-compresion.png

Examples of elements that support this effort are:

  • Legs of a chair.
  • Columns of a building.

Flexion

The bending stress tends to bend the structure:

_images/esfuerzo-flexion.png

Examples of elements that support this effort are:

  • Board of a chair.
  • Building floors.
  • Crane arm.

Torsion

Torque tends to twist the structure:

_images/esfuerzo-torsion.png

Examples of elements that support this effort are:

  • Shaft of a screwdriver.
  • Key when turning.
  • Axle of a tap.

Cutting or shearing

The shear stress or shear stress tends to cut the structure in two:

_images/esfuerzo-cortante.png

Examples of elements that support this effort are:

  • Paper cut with scissors.
  • Horizontal beam that rests on a vertical beam.
  • Screw that supports a painting.

Exercises

  1. Find two examples of tensile stresses that are not on this page.

  2. Find two examples of compressive stresses that are not on this page.

  3. Find two examples of bending stresses that are not on this page.

  4. Find two examples of torques that are not on this page.

  5. Find two examples of shear stresses that are not on this page.

  6. Draw and name the efforts that appear in a swing when a child climbs onto the seat.

    _images/mecan-columpio.png

  7. Analyze the forces that appear on a table when a weight is placed on it.

  8. Analyzes the forces that appear in a crane when it lifts a load.