Abstractac unit 1

Abstractac unit 1

1. 1-Structures

   • A structure is the set of elements in a body that made to resist the effects of the forces that act on it. A structure prevebts a body from breaking or deforming.
   • 1.1-Natural and man-made structures
     • Natural structres: Are not made by man. They are in living beings, in their composition, or the result of a geological process. Example: The shell of a crab, a bird's net or a cabe.
     • Man-made structures: Are made by people to saisfy a need. Example: The legs of a table or the case of a camera.

2. 2- Forces and loads

   • A force is anything that can deform a body (static effect) or make it move or stop (dynamic effect)
   • A load is a force that acts on a structure. It can be fixed or variable.
     • TYPES
       • Fixed or permanent loads: are constant-they don't vary over time. Example: The weight of the structure of a bridge and its components parts. (columns, road surface,...)
       • Variable loads: Vary over time. Example: The traffic going across a bridge or the wing hitting it.

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