Week 9: Bridget Breslin

In week eight, the team’s main focus was to expand the bridge. The initial plan was to keep the original design of the 24 inch span and to adjust it to reach a span of 36 inches. After testing this design and modifying it many times, the team was able to conclude that this plan would not work. After much observation and discussion it was decided that the team would have to start from scratch with a new design. The new design for the bridge has an increased height. The bridge is much taller than was originally planned. However, even though the bridge was completely redesigned, many elements that appeared to be very successful in the old bridge were incorporated. The new bridge is more expensive, however is likely to hold around 35 pounds.

            Now that the term has come to an end and I have had more experience with bridge building, I have learned many things. One of the main things I learned is that building a bridge is not an easy task at all. There is a lot of thought that has to go into designing a bridge. Also, a design that may work in one instance many be a terrible idea in another. Each scenario is different from the next. However, looking back at styles and techniques of preexisting bridges can aid in the design of new bridges. Simple concepts seem to work extremely well, it is not necessary to get extremely fancy unless it is needed. Bridge design also forces you to think of how the entire product will be affected by one move rather than just one specific area. A bridge is an entire unit that relies on each member to work successfully.

Week 9: Team Update

In the previous week, the group worked on extending the bridge from a twenty four inch span to a thirty six inch span. This task turned out to be much harder than it was anticipated. The team initially decided to keep the original design of the twenty four inch span and to expand the bridge using the same pattern. After testing this idea, there was little success. The team then added and took away many different aspects of the design only to lead to failure. Each trial resulted in the bridge only being able to hold approximately twenty to twenty five pounds.

            After much review and consideration, it was determined that the bridge needed to be completely redesigned. Although the design for the twenty four inch span worked very well, modifying it to reach thirty six inches would not work properly. The new design is quite different but has many of the same elements. The bridge is a lot taller than the first design was and included many different types of structure beams on the inside of the bridge. However, some elements that remained the same were the thickness of the bridge, the use of triangles, the technique to allow bending and beams used on the sides of the bridge to minimize contortion. This design for the bridge costs about $373,500 and can hold potentially thirty five pounds.

Week 9: Duane

      In the previous week, the group extended the bridge that spanned a total of two feet to three feet.  The group kept the same design, and only modified the length.  The two foot design held 47.8 pounds, the same design, just a foot longer held only 28 pounds.  Not what the group was expecting to see.  However, I did notice that many other groups were observing the same results when testing their bridge.  So modifications were made.  The group tried to keep some details of the strong, original two foot bridge in the three foot design.  Some modifications include increasing both the height and width of the bridge.  While designing and testing the new bridge, major twisting was noticed and was at fault for the failure.  Once again, modifications were made to prevent the bridge from twisting.  While testing the newest design, there was very minor twisting noticed, and the bridge was failing because of weight and not twisting which was what the group was looking for.  One thing to keep in mind, while testing the bridge some of the pieces actually broke under the weight.  Pieces included the blue gusset plates.
      I have learned many things about bridge design.  Especially that it is a lot of "trial and error".  You are constantly testing designs and then making necessary modifications and then testing again.  There are many programs available to help in the design process as well.  A program such as West Point Bridge Design is very useful because it shows the tension and compression forces on each specific member of the bridge and can help to identify any weak parts of the bridge.  With calculations, the forces on a bridge can be computed.  This leads to the design of a much stronger bridge.  Finally, I also learned that when designing a bridge attention is not only focused on the strength, but also on the price.  This is very important to realize because the government or a company usually will have a budget for you to work within.

Week 9: Amanda Ngov

The previous week allowed my group to focus on improving the bridge more. We tested different types of designs with different members and realized that the design needed to be improved on dramatically. Although we were able to create a design that held 30 lbs on a three feet span, we wanted to create a more efficient bridge. Consequently, we decided to change the entire design for the upcoming week. Research on methods to improve any type of truss design during the week was taken to consideration while recreating a bridge. It was noted that more members attached to the gussets allowed a higher weight load for the bridge. The difficulty during the reconstruction of the bridge was finding a starting point. Some members of the group were unwilling to recreate a different design because the original design did extraordinarily well during the load test, but others were willing to create the most efficient bridge. After discussion, the group decided to create a new design and test it. The design that held less weight then the new design would not be used.

In this overall experience of designing and creating a bridge, I learned how tedious the process can be. One computer program or kit can be utilized; on the other hand, numerous resources, observations and research should be considered to design a bridge. New ideas are  constantly being discovered so research is needed to experience new materials or resource to create an efficient bridge. In addition, observations of other bridge failures and successes should be taken into consideration for designs. Also, there are pros and cons to any resource and tool to build a bridge. Computer programs can give numerical values and estimates of forces but hands on kit such as Knex can show how limited certain materials are to a purchaser. Lastly, research to find more design types or methods of improving a design is vital. Discovering a site where people have done studies on number of members used in a connection joint helped my group in creating the final design. The process has shown me to explore numerous methods of designing a bridge and approaching an idea.

Comp 2: Breslin, Corey, and Ngov

Group 1 from section 035 has come to a final decision for a truss bridge. After many deliberations, experiments, and observations it was decided that a new idea for a bridge was required to make the most efficient bridge. The bridge now has a few more connection joints and many more members to allow a more graceful failure. After research and observing other bridges' failures, it appears that the failure will occur on the ends of the bridge near the reaction point. It is believed to be towards the end because there is extremely little support compared to the other connection points on the bridge. The total number of pieces used are 212 and the total cost is $373,500. It is believed that the bridge will hold roughly 35 lbs.

Week 8: Duane

    In the previous week, the group completed two tasks.  One, analyzing the forces on the members of the bridge.  Two, lengthening the bridge.  The bridge was converted from a two foot long design to a three foot long design.  One problem noticed when testing the two foot bridge was that it was just two feet, giving the group a problem when trying to place the bridge on the supports.  This new design is approximately three feet seven inches in length.  Having the extra inches will be very helpful when positioning the bridge on the supports. Analyzing the forces of the bridge was no easy task.  However, it is extremely helpful when you know the forces.
    Knowing the forces on each member is very important and crucial to make the bridge the strongest it can possibly be.  This method of analysis will be very helpful in making the group's bridge stronger.  Knowing the forces on each member will allow the group to strengthen those members.  This method is also time-saving, the group can determine the strength of the bridge without physically testing it.

Week 8: Bridget Breslin

In the previous week, the group had worked on two different aspects of the bridge project. The most difficult part of the week was analyzing the forces that were acting on the bridge. Calculations were completed to understand the mechanics of the bridge and get a better idea of how it actually worked. These calculations allowed our group to see the different weak points and strong points in the bridge structure. Having the calculations completed will allow the group to know exactly how and where to adjust the bridge to make it as strong as it possibly can. The group also worked on converting the bridge from its original two foot design into a three foot span design. The new design for the bridge has to be able to extent over a length of three feet. We decided to stick the original design pattern, just adding more parts to extend the length. After this was completed the bridge now has a length that is about three feet seven inches. Making the bridge longer allows for more leeway to position the bridge as needed during testing, whereas in the last test the bridge had a length of just about two feet, making it difficult to configure against the supports. I think in the upcoming week the team will have the greatest problem figuring out how to apply information gained from the analysis to improve the bridge design.

I believe the method of analysis used is extremely helpful. It allows one to see the strengths and flaws of the bridge without having to physically test it. The method of joints seems as if it would be sufficient for a real bridge, however would be more complicated. This method could be used to see how strong the bridge is and by using prior knowledge of bridge failures and the materials of the bridge one can make predictions of how the bridge design would work. However, further knowledge of location of the bridge would help to make better predictions. Factors of nature could affect the function of the bridge. Wind, rain, earthquakes and other types of natural disasters can cause a change in the forces on the bridge; having these numbers will help to make a better analysis.