The West Point Bridge Designer is an extremely
useful designing program. The interface is user-friendly and results from the
stress tests are simple. Colors for stress and strain in load test simulations
are straightforward and convenient for seeing where problems could occur. Real-world
conditions and restrictions are applied to the bridge, such as a limit to the
amount of materials that can be used and a limit of different member types,
shapes, and lengths. As with all engineering situations, there is not one
correct answer. Many different designs can be structurally sound, as the
program demonstrates. Load testing complies to the AASHTO truck loading code.
Adhering to Codes is essential in working with structures like bridges. The program
acts similarly to other professional structural analysis programs that are used
in the field.
However, the program is not completely accurate. Costs
are far more complicated than beam size and material type; costs include
roadways, the 3-dimensional structure, concrete and other materials, support
beams, and even labor. There are changes in weather and wind patterns that are not
factored in that could affect a structure. A prime example of this is the
Tacoma Narrows bridge, which eventually failed because of constant high winds. Load
testing is also not completely accurate. The only load tests available in WPBD
is a two-lane highway with a single truck moving in one direction. In real
bridges, traffic goes both ways and is not limited to one spot at a time. This
information is crucial to designing a real bridge. Bridges that work perfectly
in WPBD tests may quickly fail realistic load tests. Quite a few other factors
are not accounted for in the WPBD program, including fatigue on materials over
time or natural disasters like earthquakes or snow storms.
The program emphasizes that it is an introduction to
the bridge design process and is not necessarily the best program for the technical
details in a design. As far as a design program goes, the WPBD is highly
accurate and does perform many essential tests and functions.
-Belinda Lester
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