Analysis Process - Lester

   This method of analysis is accurate. The free body diagrams help calculate the load on each joint and member in a probable way. However, it is an extremely simple method that neglects other factors, such as an uneven load distribution, torque, the fact that the bridge is 3-dimensional, imperfect joints, etc. For a real bridge, this method is not sufficient. Although this week we will be using the Bridge Designer analysis to gain information on our Knex Truss and fine-tune our design, the information is not exact. The joints, members, or truss itself may not behave as the simple analysis would predict. We must keep this in mind while working this week and in Week 8 lab.

   A method of joints that applies to 3-D structures would be helpful. The load calculations could be more inclusive if each side of the truss were taken into account, as well as the support beams between them. Also, since a load is applied over a large area and not just on one joint at the midpoint, a more inclusive load calculation method would be useful. Some tools that might assist use are a protractor to measure angles, a device that measures stress and strain on a joint (if such an instrument exists), and knowledge about how forces distribute in a 3-D model. 

Hudson - Week 8

Q) Is [the Method of Joints] analysis sufficient for a real bridge? If not, why not?


I think that the Method of Joints analysis is close but not completely sufficient for a real bridge. Due to human calculating errors, I think that the MoJ analysis could prove faulty because it is a lot of calculations with quite a few places where a calculation could go wrong and throw off every calculation after that. For that reason, I would say that a computer program in addition to the MoJ analysis would be the safest way to figure out the various tension and compression forces on each member of the bridge.


Q) What further would you like to analyze and what knowledge or tools might assist you?


I think that the tension/compression force analysis is sufficient when coupled with cost to weight ratios. Using the MoJ analysis gives me a lot of information I can use in conjunction with the various bridge software to design the best possible bridge under the specifications of this project. 


This week my group plans to modify our bridge again basing the new design off of a revised version of our old design that is not only within the final specifications of the project, but that also uses the MoJ analysis and the Bridge Designer software to strengthen the main frame of the bridge.


Next week my group plans to continue revising and testing the bridge using the MoJ analysis to compare tension and compression forces between various bridge designs. 

Analysis Process-Durkin

This method of analysis gave us a lot of new information about the forces on the bridge when weight is applied, however this would not be enough when analyzing a real bridge.  The analysis gave us helpful information when considering weight applied unfortunately like WPBD it does not consider weight applied laterally.  Also the analysis does only considers loads applied at certain points on the bridge whereas a real bridge would need to consider loads at every point on the bridge not just at the joints. This analysis also does not take into consideration how the bridge will hold up in severe whether conditions such as high winds. Also other information would need to be known when analyzing a real bridge such as how heavy the flow of traffic will be and how reliable of a foundation the bridge will be built on. Knowing more about the conditions the bridge will have to hold up in as well as knowing more about weight at other points throughout would be helpful in further analysis of a bridge.

       These analysis calculations began last week, the main goal of the class was to figure out how to calculate the forces on the bridge properly. Another goal our group accomplished last week was to extend our bridge in a way that would meet the three feet requirement without losing any stability or greatly increasing the cost.  We plan to test our extended bridge this coming week and to further improve it where we see fit.  Figuring out what parts of our bridge need to be adjusted will be easier in the weeks to come now that we know how to do the analysis. Granted our group had some trouble figuring out exactly how to do the calculations at first we were eventually able to figure it out which will make these calculations easier in the future.  These calculations will help us in making our bridge more efficient, getting us closer to the final goal of low cost to high carrying capacity.