Structural Conditions and types of efforts

Structural Conditions

There are three conditions for a structure to work well:

    • Stability: the capacity of a structure to remain upright and not fall over. A structure’s center of gravity must be centered over its base and close to the ground for it to be more stable.


    • Resistance: the capacity of a structure to bear the tensions that it’s subjected to without breaking. A structure’s resistance depends on its shape and the material used to build it.🤣
    • Rigidity: all bodies deform slightly when a force is applied to them, but this deformation must not prevent the structure from fulfilling its function.

Types of Efforts

Tension or TractionCompressionBending or flexibilityShearTorsion

Consists of two equal forces in the same direction and move in opposite ways that stretch the object.

Examples: Slingshot, hanging object, rope pulled by two ends.

Consists of two equal forces that move in the same direction and move in the same way that tend to reduce the length of the object.

Examples: Column, a table leg, tighten a ball.

Forces that tend to bend the object. Flexion produces compression in the concave part of the element and pull in the opposite, the convex.

Examples: shelving, bridge, beam.


Two forces applied in contrary ways almost in the same vertical tend to cut the object.

Example: scissors

Forces that tend to twist the object.

Example: to drain a cloth.

Torsion effort
Exercise 1

Exercise:  Write in your notebook each of the following objects and describe what kind of effort are subject:

Key to open a door                                                   Cut paper with scissors

Cable with hanging lamp                                        Socks

Foot of a chair                                                           Shelf Divider

Fishing Line                                                              Saw (used to cut wood)

Point of Screwdriver                                               A column

Exercise 2

Exercise:  Draw the bridge in your notebook and write the types of forces applied in each of the parts of the bridge:

Forces in Bridge

Exercise 3

Exercise:  Try to draw the pictures below in your notebook and find what type of force is applying.

Types of Efforts


Step 3 - Rigidity and Trussing