Efforts

An effort is a force that appears when a structure receives an external force.

The forces that act on a structure are calle loads.

These are the main efforts that a structure can receive:

Traction is an effort that makes an object longer.

Compression this is the effort which squeezes or buckles an element.
When we “squeeze” and element, it becomes shorter and thicker.
When an “element” bends in the middle due to the compression forces, it “buckles”

Bending: a structure which is subjected to bending is being stretched and squeezed at the same time.

Shear: shear forces act across a material; one part of the element slides over the other.

Torsion is the name given to a turning or a twisting force.

http://contenidos.educarex.es/med/2005/15/estructuras/pagina2.htm
Thanks to: http://contenidos.educarex.es