1. The Suspension Bridge
In it’s simplest form the suspension bridge can basically be made from rope and
wood. This type of bridge has been around for a while it first being introduced in
the late 19th century. There are many positives to this bridge including the fact its
very light, a lot stronger than some other bridges, it can span distances from 600 to
2,000 meters longer than any other kind of
bridge, it’s the best for going over busy water
ways and its less materials than basically any
other bridge, however is still does cost a lot to
build. There are other downsides, which include
the fact it can’t take large loads and the wind has
a large impact on the stability bridge. The
positives defiantly outweigh the negatives.
The Bowstring Bridge
The Bowstring Bridge is a type of arch bridge because it shares the same
arch design over the top of the bridge. This arch on the bridge gives it a
high resistance to bending forces such as wind. These bridges are also
very good for long distances and are able to be made mostly from local
resources. However this bridge can cost a lot of money and the
foundations have to be adequate or else the bridge will not stay stable.
DESIGN
Our group
agreed on
designing
The well known ‘Golden Gate
Bridge’
2. our bridge as an Arch Bridge. We chose this design because it allows
the stress of the weight being placed on it to be distributed evenly
along to length of the bridge, which ultimately means it can hold
more weight, and is overall stronger. Another reason we chose this
design is because it looked challenging, which proved to be true.
METHOD
1. Move two tables approximately 20cm apart. Once you have this
gap do not change it
2. To begin constructing an arch bridge, start by constructing a beam
bridge by simply cutting into shape a piece (or multiple stuck
together for strength) into shape.
3. Build the arch by connecting straws and bending it over
connecting each end to an end of the bridge lengthways. Do this
the same on both sides
4. Cut straws into the sizes need to reach from the bridge to the arch
about a centimeter apart and stick them on with a hot glue gun.
5. Construct a base for it by making pop sticks into a support
structure as seen in the picture below and connect it to the
bottom of your bridge using a hot glue gun.
6. Add 50g masses beginning at the center of your bridge until the
bridge breaks or falls.
RESULTS
What a your finished product should resemble
3. Or bridge was quite successful and was able to hold a lot of weight and took one of
the group members standing on it to actually break it although the bridge was lop-
sided and became more so the more weights
we put onto it. When the bridge did break it
was the support beam underneath that had
failed. They collapsed sideways and led to the
failure of the whole bridge.
DISSCUSSION
Our bridge ultimately faired quite well, it held a lot of weight. Our bridge was so
strong because the actual beam part of the bridge had multiple layers and in-
between these layers were pop sticks laid out in patterns to keep the beam part
from snapping in the middle when under stress. Another factor that made our
bridge so strong was the support beams we made out of pop sticks and put
underneath. Even this was an after thought and not originally in the plans we added
it and it proved to be a great improvement. Despite its strength our bridge finally
collapsed under the weight of one of our group
members, this is when the support beams gave way
and made the bridge fail.
The only thing about our bridge that changed once
we started putting more weights on was that it
started going lop-sided as seen in the picture to the
right. The more weights we added the more it leant
over although it did not collapse sideways while we
were putting the weights on because we made sure to
distribute them evenly all over the bridge. As you can
also see in the picture to the right, at each end of the
bridge the weights were pushed right up against the edge so they could all fit on but
this caused the edges to weaken and the weights almost started falling off. They had
to be steadied for most of the time, constantly
needing readjusting.
The weights were applied evenly along the
bridge so the whole bridge took the same
amount of pressure although the bridge was
mostly affected on the edges, as they were
Picture shows
how the support
beams collapsed
The lean in the bridge
4. weaker with less support underneath however the middle stayed strong and didn’t
snap.
Despite the fact the bridge was strong and held all the weights I would change the
design slightly in the future by adding extra pop sticks as more support in the
bottom part to stop it collapsing sideways the way it did.
This experiment differs drastically to real life due to
our limited supplies, only having access to materials
such as pop sticks, straws, cardboard and other such
inferior materials out of which there is no way somebody could make an actual
bridge. Real bridges are commonly made of wood, stone, concrete and steel but we
did not have access to any materials of this sort.
As far as I can recall we did not make any mistakes that affected our final product. It
failed in the end purely because of design flaws.
CONCLUSION
The final outcome of our experiment was that we have designed and built a pretty
strong bridge. Our design, along with the added extra was a great success. It was
such a success because we made the beam multi-layered and added the extra
support. The only thing that hindered the full success of the bridge was that it leant
when weights were put on it.
Overall I would say we did pretty well and learnt a lot about the structure and
design of bridges.
BIBLIOGRAPHY
http://www.historyworld.net/wrldhis/plaintexthistories.asp?historyid=ab97
http://www.brighthubengineering.com/structural-engineering/65074-
characteristics-of-beam-bridges/#imgn_0
http://www.wisegeek.org/what-is-an-arch-bridge.htm
The weights being applied to the
bridge
