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This
project is due at the beginning of class on 31 October 2000.
Your group
is given the task of designing a pedestrian bridge somewhere
on campus. The University Architectural Guidelines specify that
the bridge must conform to the design depicted in Figure 1.
Figure
1. University Architectural Guidelines for Pedestrian
Bridges
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Furthermore,
the rectangular beam must be made of either of the following
materials:
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Material
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Density
(lb/ft3)
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Elastic
Modulus
(psi)
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Yield
Stress, sy
(psi)
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Aluminum
Alloy
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170
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10,000,000
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40,000
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Steel
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490
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30,000,000
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36,000
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Your group
must submit a report of whatever length you deem necessary.
The report must be typed and have a title page that includes
each group member's name. Section heading choices are left to
your discretion.
For your
assignment, you are required to do the following.
| 1) |
Choose
a site within the grounds of the University where you think
there should be a pedestrian bridge. Make a sketch of the
site showing any landmarks necessary so that there is no
ambiguity as to the exact location. Justify your selection.
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| 2) |
Based
on the exact location you selected in 1), estimate the bridge
span L. Also, specify the height H required of the
columns to accommodate any vehicles or other traffic that
may travel below the bridge. Justify your recommendations.
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| 3) |
Estimate
the dead and live loads (in terms of force per unit area)
that the bridge may have to support. These loads should
be presented in a table and given in terms of U.S. English
units (lbs. and feet) and SI units (newtons and meters).
Calculate the total design load T, based upon the following
equation:
T
= 1.4D + 1.7L
where
L is the total live load and D is the total dead load.
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| 4) |
Find
the optimal thickness of the rectangular beam that constitutes
the superstructure of this bridge, given the following
constraints:
| (a) |
The
width of the beam should be fixed and equal to 3.0
m |
| (b) |
Maximum
allowable tensile stress on the lower fiber of the
beam is 0.8 sy.
(Note: This should read as 0.8 times
the yield stress.) |
| (c) |
The
maximum allowable deflection of the bridge is 0.002
L. |
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| 5) |
Present
your findings in a table. |
| 6) |
Choose
a material (aluminum or steel) for your beam based upon
any cost and performance factors you consider to be important.
(Note: This will probably require you to do a little
research. Make sure you cite any sources you refer to.)
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| 7) |
Show
all design checks to ensure that the constraints are met
by the final design. |
| 8) |
Make
a sketch of the final design showing the beam cross-section
and length with all dimensions carefully designated. |
| 9) |
For
the total design load, calculate the reactions at the column
supports and draw the force and bending moment diagrams.
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| 10) |
Write
a short description (a paragraph or two) stating any arguments
you would use before a financing committee to justify the
allocation of funds for such a bridge. |
| 11) |
Do you
foresee any potential problems with your design? If so,
describe them and any solutions you might suggest as to
how they might be remedied. Specifically, what is missing
from the University Architectural Guidelines, and how might
this missing element affect your final design? Also, suggest
(in a qualitative fashion) any improvements to your design
that you might make, if the University design guidelines
could be ignored. |
| 12) |
The
last page of the report should detail the contribution of
each group member by name.
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