Introduction to structures  (Page 2/5)

Assignment for each group:

Fold each Manila sheet as illustrated in the sketches so that it will support the container with nails. Investigate all possibilities and decide which structure should support the heaviest mass. The height of your structure should be equal to the width of the Manila. You may cut and fold the cardboard, using strips of masking tape of 5cm long to stick it together in five different places. The flat, sturdy piece of cardboard is then placed over this structure, with the container of nails on top. See which structure supports the largest number of nails. Make a tick (√) on the sketch of the structure that supports the largest mass.

What kind of force have we exercised on the cardboard? A _ force, because it compresses the cardboard. The parts of a structure on which force is executed, are called supports or columns .

Background

When supports are not strong enough to resist forces exerted on them, they will collapse . Very thin and tall supports or columns will buckle and collapse.

Assignment 7B

Do the same experiment, but use a sheet of folio paper instead of cardboard.

Assignment 8A

Let’s investigate the horizontal strength of shell structures.

Note to the teacher:

Divide the class into groups. Provide each group with six A4 Manilas of the same thickness, two polystyrene glasses to serve as supports and a polystyrene glass containing a few nails to serve as the mass.

Assignment for each group:

Fold the Manila into structures that can resist a bending force. This structure is called a beam.

Do experiments with various structures and determine which one supports the largest number of nails. The length of the beam must remain the same as the original length. The nails exert pressure on the beam, while a pulling force in both directions is exerted on the lower part. Make a tick next to the beam that supports the largest number of nails.

Assignment 8B

Now try the same experiment, using a folio page.

[LO 1.3]

Assignment 9

Application :

Why are there crinkles in tin cans, corrugated cardboard and corrugated iron?

[LO 3.2]

Assignment 10

Name three ways to make a 3-D structure more stable.

1. Use _ or _ to stabilise the structure.

b. Make the _ of the structure wider.

1. Make the _ of the structure .

A _ (underground, broad part) of a building makes the walls and other structures more stable.

[LO 2.1]

Background

Types of structures

• shell structure (provides support from the outside, strength lies in the shell, quite thin, mostly curved, hollow);
• frame structure (parts are joined, provides good support from the inside, is concealed);
• solid structure (completely made up of material, is reinforced).

Many of the structures that are manufactured, are a combination of frames, shells and solid structures. Some of them look like shells, but are in fact frames covered with thin material. This thin material is called the sheet .

Assignment 11

Copy and complete the following table by making a tick in the appropriate column.