Folded Paper Beam

What to Make:

(Designers might call this the Design Brief and/or the Specification)

Make a Beam Bridge strong enough to support a small model car or train across a gap of 250mm (25cm) using only a single sheet of paper or thin card.

What to Use:

• some A4 sheets of paper or thin card
• two blocks of wood for supports (or you could use books for example)
• pencil and ruler
• scissors (these can also be used for scoring folds before you bend them)
• Paper Trimmer (if available)
• P.V.A. glue, Glue Stick or similar

Things to think about:

Place a sheet of thin card between two blocks of wood or books to create a simple beam bridge. Note that the card can hardly support its own weight and soon bends or deflects if an extra load is added.

Bridges have to support two loads: their own weight and any loads they need to carry. Their own weight is a fixed amount and is known as the Dead Load. The extra amount a bridge has to carry can vary as traffic passes over and it is known as the Live Load.

Think about how you can stop the paper or card beam from bending so much just by folding and/or rolling it.

Some ideas:

Ways of Making:

Paper and thin card can be cut easily with scissors or a Paper Trimmer. Edges of tubes can be overlapped and glued by brushing on PVA or using a Glue Stick.

When folding paper, and especially thin card, along its length, it is best to score the fold line using the back of a pair of scissors along a ruler or straight edge. This helps to ensure a good neat straight fold.

Testing Final Design:

When you have tried different ways of folding and rolling sheets of paper or thin card, decide how you will make your Beam Bridge and try it out to see if it works.

Make sure your design will have enough space for a flat road or railway.

Remember that roads and railways could go through a hollow beam as well as over.

Further work:

The length (or span) of the bridge is not allowed to change but your design will have altered both the width and the depth of the beam when compared with the original flat sheet of paper or card.

Which of these changes made the Beam bridge stronger - was it:

• Making the Beam Bridge narrower?
• Making the Beam Bridge deeper?
• Making the bridge as a tube?
• Can you think of a fair test to prove that what you think is true?

Think about bridges in your area. You may be able to visit some or Collect Pictures of Bridges and Ask Questions About Them.

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