Competition
You are a group of
engineers challenged to
make a new bridge across
the Thames to the
houses of parliament.
The government has very little money, so you have
limited materials.
The best bridge will win a contract to make
their bridge.
Rules
Design and make a bridge to cross a 30cm gap
across two stools, using 40 straws.
Sticky tape can not be wrapped around and
around.
Test the maximum mass the bridge can take.
The bridge that can take
the most weight is the
winner!!
Engineering project:
Research
Construct
Design
Test
Criticise and Improve!
Research
When starting our engineering project, we
need to consider three important things....
Economics
Economics
Money it will cost to build
Vs
Money it will generate when built
How can we keep costs low?
•Take less time
•Have less staff
•Use less materials
Golden gate bridge
The project cost more than
$35 million to build and took
over four years.
Provided essential route to
mainland San Francisco
Safety
How safe is it for the public to use?
How safe is it to build for
workers?
Ethics
Where is it being built?
Will people lose out if a new
bridge is made?
Science - Forces and Physics!!
Simple beam bridge - rigid horizontal structure
that is resting on two piers
The weight is acting directly downward, through
the centre of mass
Science – Forces and Physics!!
Tension is a force that
acts to expand or
lengthen an object.
Compression is a
force that acts to
compress or shorten
an object.
If the tension is too
large we get snapping.
If the compression is
too large we get
buckling.
How do engineers design bridges
to make these forces smaller??
Truss - Creates both a very rigid structure
It transfers the load from a single point to a
considerably wider area
Arch bridges
Always under compression.
The force of compression is
pushed outward along the curve
of the arch to the piers.
This greatly reduces the
effects of tension on the
underside of the arch.
The smaller the semicircle of
the arch, the greater the
tension relief effect.
Sydney Harbour
Bridge
Australia
Kintai Bridge
Iwakuni, Japan
Design
Research
Construct
Test
Criticise and Improve!
Rules
Design and make a bridge to cross a 30cm gap.
Use as much of the materials provided as you like.
Test the maximum mass the bridge can take.
Divide this by the weight of the bridge to get the
score for the bridge
Bridge score =
Max. Mass
Bridge Mass