We see constructions everywhere and every day. They may seem simple, but a lot of thought and experience went into making them. The following text will try to give you an understanding some of the most important aspects of a construction: Sturdiness (=stevigheid) and rigidness (=niet vervormbaar)
Everything that is made up of two or more parts is a construction. Most constructions need to be sturdy and rigid to resist forces. Examples of these constructions are buildings, bridges and bicycles. The pendulum that you are going to construct in this project is also a construction.
Which forces influence a construction?
Think of a triangle that is made from sturdy material such as wood (see figure on the right). If you push on corner 1 the sides of the triangle will not move. If you pull at corner 1 the sides will also not move. This triangle is resistant to both stretch and compress forces. A shape is rigid if you cannot move the corners or sides relative to each other.
If you look at the figure to the right you can see what happens to a rectangle if a force is applied to corner 1. Corners '1' and '3' move closer and '2' and '4' move away from eachother.
To make a rectangle rigid we need to make sure that the corners cannot move relative from each other. A few solutions are shown below.
Below are examples that illustrate this proces.
Take a look at the support beams of the fire station. Because of the way these are construced you create a lot of open space inside the station.
Do you see the pylon? completly made of triangles.
Why is that cross-beam there? You should be able to explain that with stretch and compress forces.
To the left is a part of the roof of the arena. Again we see the use of the sturdy triangle. Because of these triangles and the use of arches (which we will not cover here), the roof spans over 177 meter!
They're building a big hall in the left picture. You can see the skeleton is made of steal beams. They all form rectangles, which are not study. That is why you see the cross beams in the upper right. These form triangles which makes the building sturdy.
You all know these, the signs above the highways. The distance is pretty big, more than 6 lanes! This is possible because of a sturdy construction.
Sometimes you want arms to not fall down. A overhang, a roof above the door, a sunshade. How do we solve this problem? Below are possible solutions to these problems. Can you see where and how the forces apply? Try to figure out why the solution works.
The right side of the horizontal beam wants to fall down. The same thing happens when you try to keep your arm horizontal. This problem can be solved in two ways.