Week 4 Post

1. What did you do in the prior week?
I worked on designing a new bridge with much less cost and less use of materials. The bridge I designed was roughly $262,000.00 and was 600 thousand less than the one I built two weeks ago. I still need to work on the design to get close to the 200K mark that some students were at a week ago and attempt to surpass their efforts.


2. What do you and your team have planned for the upcoming week?
The group is going to continue to build off of our current designs in which we have 3-6 working ones. We will also start getting together to combine ideas in order to consolidate the best aspects of each design into one ultimate bridge.


3. Major accomplishments of the week for the team
The bridge that we designed during the course of the week 3 class turned out to be the most important completion of the term for our group and definitely sparked some thoughts as to where our next path will be in future designs.

Some important information I found on Internet:
TIPS FOR WEST POINT BRIDGE DESIGN
Tip #1
According to the contest rules, your design submission will be rejected if it is identical to one already submitted by someone else. So it is in your best interest to submit a design as soon as possible after the contest starts. There's no limit on the number of entries you may submit, so you can keep trying to improve your design -- even after you have submitted it for judging.
Tip #2
To learn how to reduce the cost of your design, start up WPBD 2007 and click the Help menu, then select "How to Design a Bridge…." On the diagram, click the blocks labeled "Optimize the Member Properties," "Optimize the Shape of the Truss," and "Find the Optimum Truss Configuration." Read each of these articles carefully.
Tip #3
It is usually (but not always) most economical to use hollow tubes for compression members and solid bars for tension members. To determine which members are in tension and which are in compression, run the load test. Compression members turn red during the load test animation and tension members turn blue.
Tip #4
If a member fails the load test, there are three ways to make it stronger:
(1) Increase the member size.
(2) Use a stronger type of steel.
(3) If the member is in compression, make it shorter. (Note: The strength of a tension member is not affected by its length.) You can shorten a compression member by moving joints or by splitting a single member into two.
Tip 5: To minimize the cost of your design, you need to understand how the West Point Bridge Designer calculates the cost of your bridge. The cost consists of four components:
1. Material Cost.
2. Connection Cost.
3. Product Cost.
4. Site Cost.
The Material Cost is simply the cost per kilogram of steel. The stronger the steel, the more it costs per kilogram. Hollow tubes cost more per kilogram than solid bars. The Connection Cost is a fixed cost of $150 for each joint in your structural model. The Product Cost is a $600 charge for each “product” used in your design. A “product” is defined as any unique combination of material, section, and size. For example, the following would be counted as four different products: 120mm x 120mm carbon steel bars, 100mm x 100mm carbon steel bars, 120mm x 120mm carbon steel tubes, and 120mm x 120mm quenched & tempered steel bars. A design that included various numbers of these four products would have a total Product Cost of 4 x $600 = $2400.
To see the cost calculations for your design, click the Report Cost Calculations button on the main toolbar.
Tip #6
To greatly speed up the process of optimizing your design, you can switch off the Load Test Animation. To do this, click the Test menu, then select Load Test Options and uncheck the "Display the Animation" box.
Tip #7
To greatly speed up the process of optimizing your design, use the sorting and "block selection" features of the Member List. To learn more about these features, read the "Member List" topic in the West Point Bridge Designer Help file.
Tip #8
Use the "high-resolution grid" setting to fine-tune the positions of the joints in your structural model. In the high-resolution mode, you can place joints at 0.25 meter intervals, in order to achieve an optimal truss configuration.

4. Issues that the team or you as an individual faces

Transforming our 2-d design into a 3-d Knex structure will prove to be a difficult feat in the upcoming weeks.

You've now used the West Point Bridge Designer for several weeks. Address the question of how realistic you think it is (or is not) in terms of what's necessary to design a real bridge. Hint: the program help file has some very good material.

WPBD seems to be a reasonable starting program for those just starting and learning to design bridges although other factors like wind are not taken into account.