Structures & Forces

Structures and form
1. Types of structures
  1. Frame structures
    1. A structure that is held up by a series of frames like a house
  2. Solid structures
    1. A Structure that is held up by itself and supports its own weight (mostly)
  3. Shell structures
    1. A structure that is held up by an outer shell and is usually hollow inside
2. What The Strength of a Structure Depends on
  1. Materials used in making the structure matter.
    1. Strong materials like iron would be good for building a structure that has to take a lot of weight and load. This is because the material can hold more load and withstand more forces acting on it. This means the structure will not fail as easily.
    2. Weak materials such as wood and glass break easily, and may look pleasing but will not hold up and will undergo structural stress and then failure.
  2. Shapes used to make the strutures
    1. Triangles are the strongest because they form a fixed rigid shape and because the angles at their corners can not change unless you change the length of the sides.
    2. Circles are generally thought of as the weakest shape to put into a structure. This is only true sometimes. Sometimes they are good though. For example, an airplane's windows crack and shatter if they are square. This is because of the 90° angle in the squares. The pressure from the air outside causes structural failure. They are not the best choice because they have to corners. This is a bad thing because there are no easy points to put a support beam for example.
    3. Squares are not the best choice because of the 90° angle on each corner. A 90° angle is quite easily snapped or broken.
3. Form is the shape that a structure takes, and is highly dependent on the materials used in the making of the item (ie.) a bridge
Forces
1. A force is something that executes pressure on a structure by pushing or pulling it.
2. External forces
  1. Winds and earthquakes
    1. Wind usually bends or something or causes torsion. For example, this picture to the left.
    2. Earthquakes are a force that cause compression to an object. For example, the picture to the left.
  2. Gravity & loads
    1. The imaganary line representing the force of gravity, should pass through the base of the structure.
      1. Symmetry follows the rule of the center of gravity
        Structures are often made symmetrical to make them aesthetically pleasing and used to distribute the weight evenly in order to make the structure more stable.
        If the center of gravity is too high, the structure is less stable. Like the Leaning Tower of Pissa
        If the line of gravity is outside the base, the structure will be unstable.
    2. Load puts pressure on the structure and if the structure is not built properly, may cause it to fail.
3. Internal forces
  1. Tension
  2. Torsion
  3. Shear
  4. Compression
4. The effect of force depends upon its amount, direction in which it acts on that structure and the point that it is applied.

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Structures & Forces

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	Created by Josephxl over 10 years ago