Design Brief- We were asked to build a bridge by utilizing West Point Bridge Designer software. The cost of the bridge must not have exceeded $400,000 and had to cross the vally at any elevation from water level to 24 meters above, with the bridge not reaching 32.5 m above water level. The bridge structure could consist of either standard abutments or arch abutments and, if necessary, 1 immediate pier and cable anchorages, located 8 meters behind the abutments. There were to be no more than 50 joints and 120 members. The deck of the bridge had to have been flat and 10 meters wide. Each member of the truss had to be made of either carbon steel, high-strength low-alloy steel, or quenched and tempered steel as either solid bars or hollow tubes.
Research Summary- During my research, I found that the stronger materials were more expensive, while the materials that were not as strong were more cost-efficient. I also found that the cost of the members were higher when the size was increased, as the cost decreased as the size was decreased.
Final Design Justification- I chose to use carbon steel bars because it was the cheapest option as opposed to using high-strength low alloy steel or quenched steel, which were more expensive. Carbon steel worked just fine so using the other two options were not necessary. I used the design I used because I expected the costs to be cheaper. While my prediction was incorrect, the cost of the bridge still fell under the allotted cap number of $400,000 at $325,223.04.
Reflection- While working on this project, I learned that it is hard to balance out cost and efficiency when building a bridge. I found it interesting that my bridge was so simple, yet it still barely fit under the allotted cap space. Next time, I would try different methods of building the bridge in hopes that I can build a cheaper alternative.
References- West Point Bridge Designer 2013
Conclusion Questions-
How does the type and direction of stress applied affect the selection of the material type and the cross-sectional area?- If there is more stress applied in one spot as opposed to another, a stronger material or different cross-sectional area will add strength to that particular area, preventing it from failing.
How can the forces of compression and tension work together to make a stronger bridge?- The forces of tension and compression work together by pushing pieces of the bridge together, which ensures even weight distribution, and ensures joint contact.
How does the type and direction of stress applied affect the selection of the material type and the cross-sectional area?- If there is more stress applied in one spot as opposed to another, a stronger material or different cross-sectional area will add strength to that particular area, preventing it from failing.
How can the forces of compression and tension work together to make a stronger bridge?- The forces of tension and compression work together by pushing pieces of the bridge together, which ensures even weight distribution, and ensures joint contact.