Structural Element Behavior Under Different Forces

Tension is a type of stress that a structural element experiences when subjected to two equal and opposite forces pulling outwards along the same axis.

These forces:

• Act on either side of the element.
• Are equal in magnitude.
• Are aligned along the element's axis.
• Pull in opposite directions.

If these forces deform the element, it will stretch. If the element fails, it will break in the middle, perpendicular to the force direction.

Compression is a type of stress that a structural element experiences when subjected to two equal and opposite forces pushing inwards along the same axis.

These forces:

• Act on either side of the element.
• Are equal in magnitude.
• Are aligned along the element's axis.
• Push in opposite directions.

If these forces deform the element, it will compress. If the element fails, it will break in the middle, perpendicular to the force direction.

Bending is a type of stress that a structural element experiences when subjected to three parallel forces across its axis.

These forces:

• Act on either side of the element with a third force in the middle.
• The middle force equals the sum of the other two.
• Are parallel and across the element.
• The middle force acts in the opposite direction to the other two.

If the element's shape changes, it will bend.

Consider an element designed to withstand bending, made from a material with 50 kg/cm² tensile strength and 70 kg/cm² compressive strength. How much force can it withstand? Why?

Because the part of the element under tension cannot withstand more than 50 kg/cm². When an element bends, part of it experiences compression, and part experiences tension. Since the material's tensile strength is 50 kg/cm², the part under tension will begin to deform, even though the part under compression could withstand up to 70 kg/cm².

Types of Structures:

Frame Structures: (e.g., bolted, nutted, or welded structures)

Shell Structures: (e.g., eggshells, cardboard boxes, airplanes, cars)

Arch Structures: (e.g., Roman arches)

Mixed Structures: (e.g., chalets, houses)

Mass Structures: Natural (e.g., mountains) or Artificial (e.g., walls, sandcastles)

Suspension Structures: (e.g., suspension bridges)

Types of Unions:

Permanent Unions: (e.g., glue, rivets, welding)

Non-Permanent Unions: (e.g., nuts, bolts)