A1 - FRANCO

I have designed my first bridge following the use of triangles.  The reason is, that with the advantage of their strength and sustainability if done properly, less material would be necessary for the needed amount of strength, which would also make it a more affordable bridge.

My bridge began using a lot more material and smaller similar shapes of triangles.  As I modified the bridge and its angles, I was able to gradually remove material used and make it more economic.

Current bridge cost:  $354,192.01
Estimated bridge cost (future improvements included):  $425,000.00

During the making of this design I learned that not only does the length of a rod matter, but also do the angles and it can significantly affect the way the force sustained is distributed.

Research Questions

During class in week 3, Mr. Jay Bhatt, Drexel University's research librarian, will be visiting to help students with strategies for research. In week 2, Mr. Bhatt spoke to the entire Engineering 103 student body about using the library's website as a main research tool. He showed us where to find different databases to search all sorts of subjects and he helped us to understand which resources to use to find certain types of information.

After completing my first bridge design for Engineering 103 using the West Point Bridge Designer computer program, I have begun to notice patterns that fail and patterns that are successful for bridge truss designs. I have specifically noticed that on alot of designs I came up with, the top of my truss was weaker than the bottom. I understand that this is because of the way weight is dispersed across the bridge, but I would like to learn more about strong triangular designs commonly used in trusses and what it is about these designs thats makes them so popular.

I am hoping that Mr. Bhatt will be able to help me find resources to answer the following questions:

1. Does the design of a truss above/below the road surface of a bridge affect the bridge's potential strength? If so, does placing a truss above the roach surface of the bridge make the bridge stronger or weaker?
2. Is it better for a truss to be made of small triangles of equal size or large triangles of varying sizes?
3. Is there a certain way to go about designing a truss? Are there any base-designs or patterns to follow other than using all triangles?

Research Questions

Mr. Bhatt was introduced to the engineering student body during week two of the quarter.  He spent an hour informing us of all the great resources there are out there on the web for us to use, especially when we need information regarding engineering.  These seem like very helpful places to go when researching for projects.  I am sure I will use at least one of the resources he discussed when researching about bridges.  

However, I still have a few questions as to how to go about my research.  One thing I would definitely like to know is where exactly to start researching them online.  Are there better websites than others?  How do I know what websites will be the easiest to understand?  Is there somewhere I can go to learn about the general formation of truss bridges?  For someone who knows absolutely nothing about bridges, what’s a good beginner website to start my research at?  These are just a few questions that would be really helpful.  My biggest concern is that I will only find websites that are hard to understand and that will go into very detailed explanations.  First, I need to learn and know the basics about bridges before I will be ready to conquer the harder descriptions. 

On a more detailed note, I would also like specific questions about bridges answered.  I noticed that there are two major ways to design a bridge on WPBD.  What are the pros and cons of building the truss above/below the bridge?  I also would like to know how to make the strongest bridge.  I know that triangles are a must, but should they be big or small? Equilateral or all different shapes? I am hoping that Mr. Bhatt can answer these questions and more in Wednesday’s lab.

A1-O'CALLAGHAN

Goals for my bridge design:

• Truss design consist mostly of triangles
• Have a general square shape for the bridge
• Have a two lane truss bridge that did not include pillars 
•  Keep the cost down 
•  Use as few members as possible and still be considered steady

                                                            View of bridge in building mode









                                                                   Image of truck in center of bridge


                                                   Load Test Results

My design originally changed from when I started the design process.  I am still getting used to WPBD the program, so a lot of things I did were experimental.  I started out thinking that a lot of small triangles would be best, but I soon realized that it was also more expensive.  I basically tried to come up with the cheapest bridge I could that supported the truck.  I learned that members couldn’t be too thin and I had to find a happy medium in the length of each member.  Overall, I am happy with the design since it is my first time designing a bridge. 

The cost estimate turned out to be $438,282.34.  I played around with a few other designs and out of the three bridges I saved, this one was the cheapest.  I hope to eventually decrease this to under $400,000 but I feel this will take practice and patience.  

Overall, I learned how to use WPBD and how to build a beginner bridge.  I found the load test results to be very useful and the truck simulator to really help me understand why my bridge was failing at certain points.  In the future I hope to build upon my knowledge so I can improve my bridge building skills and create more efficient and stronger designs.