Process Observations - Hudson

While working with the West Point Bridge Design software, there are a few things I have noticed.
1) The bridge design will only show one truck going across one way. This is a fairly unrealistic scenario for a two lane bridge. Chances are, at some point there are going to be multiple cars going multiple directions at different places on the bridge and it seems like this is one area where the WPBD software isn't exactly the best.
The software also doesn't take into account weather forces. Constant wind, rain, ice, sun, or a mixture of these forces can be the downfall of a bridge. Frequent freezing and thawing can create micro-cracks in the structure and wind could cause the structure to bend in unusual ways.
2) The bridge cost does not take a lot of other factors into consideration. While joints and bars are important, what is more important is the cost of labor, foundation, decking, paving, nuts and bolts... there are a lot more considerations when building a bridge than just the joints and bars.
The bridge cost also seems to be outdated. While theoretically I can build a bridge for $250,000, that's probably not the case if I was to actually set about building the bridge I designed.
3) The bridge can't be modeled over time. Bars and beams are going to get weaker over time and if the bridge is painted frequently that's added weight and stress on the bridge that isn't being taken into consideration. If the bridge just barely passes to begin with, over time the structure might become weak enough that it collapses.

With this in mind, I still think the WPBD software is excellent for beginning bridge designs and our uses. It's not overly complicated, but it still has several different options for most choices. It helps people get a basic understanding of what works and what doesn't work and a ballpark range of what the bridge might cost.

WPBD Process Observations - Lester

The West Point Bridge Designer is an extremely useful designing program. The interface is user-friendly and results from the stress tests are simple. Colors for stress and strain in load test simulations are straightforward and convenient for seeing where problems could occur. Real-world conditions and restrictions are applied to the bridge, such as a limit to the amount of materials that can be used and a limit of different member types, shapes, and lengths. As with all engineering situations, there is not one correct answer. Many different designs can be structurally sound, as the program demonstrates. Load testing complies to the AASHTO truck loading code. Adhering to Codes is essential in working with structures like bridges. The program acts similarly to other professional structural analysis programs that are used in the field.

However, the program is not completely accurate. Costs are far more complicated than beam size and material type; costs include roadways, the 3-dimensional structure, concrete and other materials, support beams, and even labor. There are changes in weather and wind patterns that are not factored in that could affect a structure. A prime example of this is the Tacoma Narrows bridge, which eventually failed because of constant high winds. Load testing is also not completely accurate. The only load tests available in WPBD is a two-lane highway with a single truck moving in one direction. In real bridges, traffic goes both ways and is not limited to one spot at a time. This information is crucial to designing a real bridge. Bridges that work perfectly in WPBD tests may quickly fail realistic load tests. Quite a few other factors are not accounted for in the WPBD program, including fatigue on materials over time or natural disasters like earthquakes or snow storms.

The program emphasizes that it is an introduction to the bridge design process and is not necessarily the best program for the technical details in a design. As far as a design program goes, the WPBD is highly accurate and does perform many essential tests and functions.

-Belinda Lester 

Process Observations-Durkin

WPBD is an educational engineering program that can teach a student a lot about bridges but falls short in a number of areas when it comes to real world bridge design.  For example the program does not consider secondary members, three-dimensional stability of the bridge, or the many types of member failure. WPBD also does not consider how the bridge will hold up under environmental stresses or how it will effect its surrounding environment. This is important because the ground that the bridge is built on needs to be strong enough to support that bridge and the bridge need to be strong enough to with stand erosion that the ground and water will be under it. WPBD also does not take into consideration how the bridge would fair in the case of a natural disaster.  Leaving out these environmental factors makes it important to see WPBD as an educational program alone. The program also only takes things like cost and some measures of stability into consideration leaving out aesthetics and the amount that the bridge bends as criterion. WPBD also falls short when it comes to the type and distribution of weight that it considers when it comes to traffic. It only considers two types of traffic and traffic in only one direction when testing the bridge.  Also during testing the lateral position of the weight of traffic on the bridge is not considered. The program also does not use the exact cost of materials or consider the cost of labor to build the bridge as these can change with the economy and other factors.

~Jacquelyn Durkin

Research Questions - Lester

1. Where in the Library are there books on civil engineering?
2. Are there books about bridges that also include pictures?
3. How does one find information on trusses specifically?

Research Question-Durkin

1) What is the longest bridge in the world?
2) What is the oldest bridge still standing today and what makes it so durable?
3) What is the most expensive bridge in the world?

~Jacquelyn Durkin

Research Questions - Hudson

1) Are bridges stronger when they are built with trusses supporting the weight from below or above?

2) What famous truss bridges are still standing throughout the world?

3) What is the longest truss bridge that can be built that still supports traffic?

A1-Hudson

1) My bridge design goal was to make the most cost effective bridge possible. My bridge is the shape it is because I found this shape to be the most cost effective and it seemed to bear the weight of the bridge better than my first designs.

2)

Image 1: 2D view of the bridge in Drawing Board mode. 

3)

Image 2: View of the bridge in Test mode with a truck in the center.

4)

Image 3: Load test results numbers 1 through 38.

Image 4: Load test results numbers 6 through 43.

5)

Image 6: Bridge in Test mode with trusses above the bridge.

During the designing process, I went from attempting to build a bridge where the weight of the bridge is supported by trusses that are over the bridge (Image 5) to a bridge where the weight was supported by trusses under the bridge (Image 1 and Image 2). I found this to be more cost effective and less prone to errors. I started out this way because most of the bridges I have ever seen have the weight supported from above rather than below, but while designing my own bridge I realized there were far too many problems with how the weight is distributed while the truck is crossing the bridge. 

6) My current bridge cost, as seen in Image 1, is 393,202 dollars and 44 cents. I think this could be brought down to under 350,000 dollars at least, possibly even under 300,000 dollars with further time and knowledge by eliminating bars and joints. 

7) While building this bridge I learned that sometimes designs that seem good on paper do not actually work out in real life. My bridge would seem stable but when the truck drove onto the bridge it would buckle in unexpected places, like the very middle of the road. I also learned that there are some support bars that are fundamental to whether the bridge will work or not and other bars that, while they seem important, can be taken out with no major impact to the strength and durability of the bridge.

A1-Durkin

Dennis H. Mahan Memorial Bridge
Project ID: 00001A-
Designed By:
# Material Type Cross Section Size (mm) Length (m) Compression Force Compression Strength Compression Status Tension Force Tension Strength Tension Status
1 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 684.28 4655.00 OK
2 CS Solid Bar 140x140 3.61 671.57 2900.89 OK 0.00 4655.00 OK
3 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 467.64 4655.00 OK
4 CS Solid Bar 140x140 3.61 450.40 2900.89 OK 0.00 4655.00 OK
5 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 393.02 4655.00 OK
6 CS Solid Bar 140x140 3.61 375.78 2900.89 OK 0.00 4655.00 OK
7 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 304.45 4655.00 OK
8 CS Solid Bar 140x140 3.61 287.21 2900.89 OK 0.00 4655.00 OK
9 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 199.87 4655.00 OK
10 CS Solid Bar 140x140 3.61 182.63 2900.89 OK 0.00 4655.00 OK
11 CS Solid Bar 140x140 3.61 49.70 2900.89 OK 95.17 4655.00 OK
12 CS Solid Bar 140x140 3.61 77.93 2900.89 OK 66.94 4655.00 OK
13 CS Solid Bar 140x140 3.61 154.43 2900.89 OK 0.00 4655.00 OK
14 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 171.67 4655.00 OK
15 CS Solid Bar 140x140 3.61 258.94 2900.89 OK 0.00 4655.00 OK
16 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 276.18 4655.00 OK
17 CS Solid Bar 140x140 3.61 346.97 2900.89 OK 0.00 4655.00 OK
18 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 364.21 4655.00 OK
19 CS Solid Bar 140x140 3.61 422.18 2900.89 OK 0.00 4655.00 OK
20 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 439.42 4655.00 OK
21 CS Solid Bar 140x140 3.61 650.53 2900.89 OK 0.00 4655.00 OK
22 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 663.24 4655.00 OK
23 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 752.09 4655.00 OK
24 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1231.45 4655.00 OK
25 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1611.73 4655.00 OK
26 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1877.15 4655.00 OK
27 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 2008.20 4655.00 OK
28 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 2004.55 4655.00 OK
29 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1866.21 4655.00 OK
30 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1593.46 4655.00 OK
31 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 1206.67 4655.00 OK
32 CS Solid Bar 140x140 4.00 0.00 2633.62 OK 728.75 4655.00 OK
33 CS Solid Bar 140x140 5.39 491.54 1732.39 OK 0.00 4655.00 OK
34 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 318.03 4655.00 OK
35 CS Solid Bar 140x140 5.39 598.41 1732.39 OK 0.00 4655.00 OK
36 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 762.83 4655.00 OK
37 CS Solid Bar 140x140 5.39 499.18 1732.39 OK 0.00 4655.00 OK
38 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 637.31 4655.00 OK
39 CS Solid Bar 140x140 5.39 387.70 1732.39 OK 0.00 4655.00 OK
40 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 486.29 4655.00 OK
41 CS Solid Bar 140x140 5.39 251.32 1732.39 OK 0.00 4655.00 OK
42 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 330.06 4655.00 OK
43 CS Solid Bar 140x140 5.39 95.18 1732.39 OK 132.78 4655.00 OK
44 CS Solid Bar 140x140 5.39 89.73 1732.39 OK 173.72 4655.00 OK
45 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 289.06 4655.00 OK
46 CS Solid Bar 140x140 5.39 245.94 1732.39 OK 17.60 4655.00 OK
47 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 445.34 4655.00 OK
48 CS Solid Bar 140x140 5.39 383.00 1732.39 OK 0.00 4655.00 OK
49 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 596.50 4655.00 OK
50 CS Solid Bar 140x140 5.39 496.79 1732.39 OK 0.00 4655.00 OK
51 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 723.23 4655.00 OK
52 CS Solid Bar 140x140 5.39 600.45 1732.39 OK 0.00 4655.00 OK
53 CS Solid Bar 140x140 5.39 0.00 1732.39 OK 305.21 4655.00 OK
54 CS Solid Bar 140x140 5.39 478.87 1732.39 OK 0.00 4655.00 OK
55 CS Solid Bar 140x140 4.00 234.50 2633.62 OK 0.00 4655.00 OK
56 CS Solid Bar 140x140 4.00 421.01 2633.62 OK 0.00 4655.00 OK
57 CS Solid Bar 140x140 4.00 419.34 2633.62 OK 0.00 4655.00 OK
58 CS Solid Bar 140x140 4.00 457.78 2633.62 OK 0.00 4655.00 OK
59 CS Solid Bar 140x140 4.00 487.46 2633.62 OK 0.00 4655.00 OK
60 CS Solid Bar 140x140 4.00 488.39 2633.62 OK 0.00 4655.00 OK
61 CS Solid Bar 140x140 4.00 460.53 2633.62 OK 0.00 4655.00 OK
62 CS Solid Bar 140x140 4.00 423.59 2633.62 OK 0.00 4655.00 OK
63 CS Solid Bar 140x140 4.00 425.90 2633.62 OK 0.00 4655.00 OK
64 CS Solid Bar 140x140 4.00 242.37 2633.62 OK 0.00 4655.00 OK
65 CS Solid Bar 140x140 3.61 210.26 2900.89 OK 0.00 4655.00 OK
66 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 429.42 4655.00 OK
67 CS Solid Bar 140x140 3.61 451.36 2900.89 OK 0.00 4655.00 OK
68 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 434.12 4655.00 OK
69 CS Solid Bar 140x140 3.61 302.36 2900.89 OK 0.00 4655.00 OK
70 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 285.12 4655.00 OK
71 CS Solid Bar 140x140 3.61 197.14 2900.89 OK 0.00 4655.00 OK
72 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 179.90 4655.00 OK
73 CS Solid Bar 140x140 3.61 114.10 2900.89 OK 13.61 4655.00 OK
74 CS Solid Bar 140x140 3.61 30.85 2900.89 OK 96.86 4655.00 OK
75 CS Solid Bar 140x140 3.61 31.27 2900.89 OK 96.34 4655.00 OK
76 CS Solid Bar 140x140 3.61 113.57 2900.89 OK 14.03 4655.00 OK
77 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 179.27 4655.00 OK
78 CS Solid Bar 140x140 3.61 196.51 2900.89 OK 0.00 4655.00 OK
79 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 283.79 4655.00 OK
80 CS Solid Bar 140x140 3.61 301.03 2900.89 OK 0.00 4655.00 OK
81 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 430.79 4655.00 OK
82 CS Solid Bar 140x140 3.61 448.03 2900.89 OK 0.00 4655.00 OK
83 CS Solid Bar 140x140 3.61 0.00 2900.89 OK 422.27 4655.00 OK
84 CS Solid Bar 140x140 3.61 209.00 2900.89 OK 0.00 4655.00 OK
85 CS Solid Bar 140x140 4.00 611.63 2633.62 OK 0.00 4655.00 OK
86 CS Solid Bar 140x140 4.00 1077.31 2633.62 OK 0.00 4655.00 OK
87 CS Solid Bar 140x140 4.00 1362.86 2633.62 OK 0.00 4655.00 OK
88 CS Solid Bar 140x140 4.00 1517.60 2633.62 OK 0.00 4655.00 OK
89 CS Solid Bar 140x140 4.00 1566.25 2633.62 OK 0.00 4655.00 OK
90 CS Solid Bar 140x140 4.00 1509.14 2633.62 OK 0.00 4655.00 OK
91 CS Solid Bar 140x140 4.00 1357.12 2633.62 OK 0.00 4655.00 OK
92 CS Solid Bar 140x140 4.00 1077.42 2633.62 OK 0.00 4655.00 OK
93 CS Solid Bar 140x140 4.00 618.34 2633.62 OK 0.00 4655.00 OK
94 CS Solid Bar 140x140 7.81 256.46 820.46 OK 0.00 4655.00 OK
95 CS Solid Bar 140x140 7.81 255.64 820.46 OK 0.00 4655.00 OK
96 CS Solid Bar 140x140 2.00 41.62 3876.74 OK 0.00 4655.00 OK
97 CS Solid Bar 140x140 5.00 587.08 1970.68 OK 0.00 4655.00 OK
98 CS Solid Bar 140x140 2.00 40.38 3876.74 OK 0.00 4655.00 OK
99 CS Solid Bar 140x140 5.00 592.88 1970.68 OK 0.00 4655.00 OK
100 CS Solid Bar 140x140 6.40 0.00 1220.68 OK 477.56 4655.00 OK
101 CS Solid Bar 140x140 6.40 0.00 1220.68 OK 481.60 4655.00 OK
102 CS Solid Bar 140x140 5.00 329.39 1970.68 OK 0.00 4655.00 OK
103 CS Solid Bar 140x140 5.00 332.44 1970.68 OK 0.00 4655.00 OK

         












 My goal for the design of this bridge was to design a bridge that is both stable and inexpensive.  I went through multiple trials before deciding on this design.  Originally I tried adding X’s instead of triangles however that seemed to add little to no stability while greatly increasing the cost. I began with a simple single level, above the road bridge design but found this to be very unstable throughout the structure. I then added extra cross beams at the ends of the bridge; this made the bridge better connected to the ground.   This fixed the initial brake that occurred during the test but still left the center of the bridge very weak.  After adding an upper layer to the single level design the bridge became more stable but was still very strained toward the center.  I then added support below which made the bridge better able to support the truck as it drove across.  Adding the layer below also seemed to help distribute the weight of the truck more evenly as there was no longer one or two points on the bridge that were under great strain at any time. Also keeping the beams of the lower layer short helped keep costs low.  I chose to stick with the original beams as opposed to switching to tubes as each time a test was done with tubes instead of beams the bridge lost stability.  This loss of stability occurred regardless of where the tube replaced the beam showing that the weight is evenly distributed.  The cut in cost that using the tubes would achieve was not worth the lack of stability they would cause. Overall the cost of the bridge came to $605,811.49.

            By using the Westpoint Bridge Designer program I learned more about stability as well as how to use features such as how to use the Compression Force/Strength Analysis to better determine which areas need more support.  I also learned about the general structure necessary to make a strong and cost efficient bridge. I found that straight lines are incredibly unstable and that although very stable X’s are not very cost efficient. I learned that symmetry was a key characteristic to a strong structure, as one side being weaker than the other would nearly always lead to a brake in the bridge. It was important to be patient during this process and to be constantly testing as each added or taken away beam could make a significant difference.

     In the week to come our group will discuss the different features of our final designs.  We will than compare and contrast the bridges to see what needs to be modified and what should be included in our final group design.  We will try and find the most cost efficient and stable properties of each bridge.

~Jacquelyn Durkin

A1 - Lester

     My goal for this design was to create the most stable bridge possible. After finding designs that were sturdy, I worked on making them less expensive to build. I went through many trials, testing various shapes like X's, backwards and forwards V's, and single or double level trusses. I began with trusses build below the road, but switched to above the road support. There was no significant difference between above and below supported trusses except the beams had a tendency to overstretch on the bottom while they overcompressed on the top. An X structure bridge, which is what I call a bridge that has crossed beams instead of stand-alone triangles as support, was my first design. Although it is very stable, it costs more to build because there are double the amount of beams needed as compared to a simple triangle structure. The equilateral triangle V's on a slope was the most stable of all my trials, according to the Compression Force/Strength Analysis column in the load test results report. The angled slope of the bridge as it goes from the beginning to the middle cuts costs, since the beams are more compact and, therefore, cost less money (since beam are priced by size). Tubes are included in the most structurally sound locations to cut costs as well. Using tubes in a few places cut the cost of this bridge by almost $100,000. This bridge costs $620,984.96 altogether.
     I learned a lot about the Westpoint Bridge Designer program, like shortcuts and stress test features. I got a feel for what a correctly build bridge should look like. Symmetry and simplicity were both extremely important factors in keeping the bridge stable while limiting building materials to keep costs low. I also learned that designing a stable bridge is not nearly as easy as I'd thought. Shapes that seem stable actually collapse at unexpected places, like a horizontal support beam in the first half of the bridge, or a vertical beam in the center. Also, despite my partial skepticism, I found that simple triangles are in fact the strongest support.
     Next week, our group will compare our final designs and discuss which we want to continue modifying and what features can be taken from each design to make our bridge the most stable and cost efficient.

Belinda Lester

Teamwork

Teamwork is an important part of Engineering. There are so many components to any Engineering project that it's just unrealistic for any one person to be able to bear the entire workload, and, thus, Engineering generally involves teams. In my past two Engineering classes I have had the misfortune of being put into teams with males who clearly believe that women have no place in Engineering. For that reason, I'm glad I'm with two other girls who seem to want to work in a team just as much as I do. While, quite often, "teamwork" translates into one person doing the work and three people getting credit, I don't think that will be the case in this class.

In order to keep everyone doing their fair share and to get all the work done in time we are going to need to budget our time effectively and communicate well. I don't see this as a setback in our group because we are communicating effectively already. We will need to keep this up though, to make sure that our ideas mesh well together and we can work out any conflict that arises.

As a team we are also going to need to work together frequently to get everything done, so it is good that we all live in the same dorm. It makes things a lot easier to work out when your team is just an elevator ride away.

I think that our team will be able to work well together as long as we keep in mind that this is a team effort and we continually communicate and plan together throughout the duration of the term.


~ Stephanie ~

Teamwork

Being able to work well with a group is an important skill, especially in engineering.  Collaboration can be an essential part of creating the best possible product.  This group will work well together but as is possible with all projects, the group may run into some issues.  As the group consists of many members there are many different points of view which can be great when coming up with new designs but also leaves open the possibility of conflicting ideas.  This is where it will be important to be able to calmly communicate with an open mind as it is rarely one persons idea that is best but rather a combination of the ideas of many.  Another possible problem that could arise would be if a group member is not taking responsibility for getting their part done and submitted on time.  These two issues tend to be the main problems that occur when doing group projects.  However with good communication, time management and a diligent work ethic the group will be able to work well together and accomplish the goal of having the best bridge design.

Jacquelyn Durkin

Teamwork

Teamwork

Projects that involve a team effort are extremely common in scientific fields such as engineering. All three Bridge Competition members bring something unique to the table. Our individual skills and inputs, when properly integrated, will result in a smoothly running project. However, some issues will inevitably arise. We must have a strict schedule and adhere to all deadlines assigned; if one person doesn’t finish their part then the whole group is affected. We will allocate weekly tasks to each other during lab time and check in via email or text message a few days before the next lab if someone still hasn’t done their part of the assignment.

A few other issues that could arise include: conflicting ideas about the final design, poor time management, not enough individual participation, or the common idea of “someone else will do it”. To deal with these, we will communicate ideas to each other clearly and considerately, as well as gently “push” our fellow group members away from procrastination. If someone is not putting enough effort into the project as they should be (without explanation), then the group will call a meeting and re-discuss role assignments to ensure everyone is on the same page.

-Belinda Lester