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(static demonstration model) |
(scale visualization model) |
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click image to enlarge |
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Fig. 189 - The parabolic curve of the suspension cables mirrors bending moment diagram |
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The main
suspension cables are spun together from thousands of strands of high
strength |
steel
wire. At the top of the towers these cables pass over a saddle that
allows the cable to |
slide as
the loads pull from either side of the tower. Here is where the
tensile stresses of |
the
cables are transferred to the towers which displace them downward as
compression |
stresses
to the ground. |
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As shown
in Fig. 189 above, suspension bridges carry their loads very efficiently
due to the |
fact
that the parabolic curve if the main cables closely conforms to the force
of the bending |
moment
experienced by the bridge along the length of its deck. Recall that
the bending |
moment
of a simply supported beam is zero at the end supports and then increases
to a |
maximum
in the middle of the beam. The same is true for a suspension
bridge. |
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Cable
stayed bridge |
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Cable
stayed bridges are similar to suspension bridges in most respects except
for the way |
that the
deck is hung from the support towers. Instead of long suspension cables that |
extend
from one end of the bridge to the other, numerous individual cables extend
directly |
from
each tower to the deck. |
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(static demonstration model) |
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(scale visualization model) |
Fig. 190 - Cable stayed bridge
click image to
enlarge |
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Back
to Knowhere |
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Page 115
- Building stability - Cable stayed bridge |
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