Disel - Week 9 Blog Entry

Last week we were able to come up with two different designs for our bridge, but from the testing we all agreed that we should use the bridge Skip designed. It's performance was really good and we worked on some changes to make it cheaper so I think we are ready for the competition. The one I designed seemed good but when tested it would not hold more than 7 pounds. Even that I made some changes still is not as good as the other bridge Skip designed. I think we are going to be one of the teams with a good ratio weight/cost.

I learned a lot from this course. I learned a lot about truss bridges. I learned how and where is necessary to use triangles and where is not. I learned that the center of the bridge should always be the strongest part of the bridge. I also learned a simple way how forces are distributed. I learned how to use WPBD software which helps a lot in calculating the cost of a bridge and distribute the forces. The best thing about this course I think was the fact that we had to make a strong bridge but not forgetting the cost. From that I learned a lot about how construction industry works in real life. The competition with other teams made it really competitive.
I'm really happy with what I learned into this course and I think some of the things I learned here are going to help me majoring as a civil engineer.

Skip Week 9 Blog Entry

The prior week, we designed our final bridge for the next week when we will actually test out the bridge. Instead of building a bridge that could hold a huge amount of weight and cost a lot of money, I decided to build a bridge that could only hold a little bit of weight, but is cheap so that the cost to performance ratio is high.  I ended up building a bridge with a basic over truss design with many right triangles. I also used the long seven inch Knex pieces and used less gussets because the weak points were at the gussets on the previous bridges we looked at. I also designed it so  The cost is about $100,000 and when we tested it, it held 14.4 pounds. This is pretty good cost performance. Disel in my group designed a bridge that had more webs and smaller trusses, but when we tested it, it only held 7 pounds and it cost a lot more than my bridge design so we decided to go with my design. Disel's bridge broke more easily probably because he had many gussets and connectors which made it easier to break. He also had the sliding gusset plates which is a common place where the bridge ruptures. The coming week, we will test out my bridge design for the final test. We will try to make the bride cheaper and stronger in preparation for the final test to improve the cost performance. The major accomplishment this week was that we were able to design a bridge that will look very close to the final design. The bridge we have right now follows all the restrictions and we are happy with how it performed when we tested it. The only thing to do now is to improve on it. The problem is that I am not sure how to improve on it. I have made the bridge as cheap as possible for the current design, and I do not know if there are parts that I can remove. Otherwise, there are no problems within the team. We all agree with the current bridge design and we are helping each other out giving ideas for the bridge.

I learned that you must consider many things when you are designing a bridge. There are many steps when designing a bridge. One of the most important things that one must consider when designing a bridge is what the client wants the bridge to be. Does he want the sturdiest, strongest bridge possible or a very cheap bridge that is not as strong? Does it have to look interesting and unique with a suave design, because it will be a symbol of a city? In this course, we were required to build a bridge with the best cost performance. We had to balance out how much it can hold, with how much it costs. Another thing that is very important is considering the restrictions. A real bridge will definitely need to span a certain distance, be able to hold at least a certain amount, be durable so it will last for a long time, and there could also be a cost range. There are many restrictions that must be followed. In this course, for example, the final bridge for next week must span 36 inches and must have a hollow inside section 3 inches wide and 2 inches tall. After you have all these things, you can start designing your bridge. When designing bridges, you must also think about how the forces of tension and compression are distributed throughout the bridge. In the course, we used basic laws of physics to see how forces of weight were distributed throughout the members of the bridge. One thing you have to remember when dong these calculations is that this is disregarding many factors such as wind and the weight of the bridge itself. For this reason, we can only use these as a reference. One more thing I learned in designing bridges is that triangles are very strong stable shapes so are good to use in the designs. This is because in a two dimensional plane you cannot change the shape of triangles once you have one unlike rectangles where you can slide a side and make a different shape.

Jonathan Week 9 Blog Entry

Last week, we were able to make some more finishing touches to our bridges. Disel got to test his version of his bridge, but it didn't turn out as good as he expected. Soichiro got to test his bridge later in the class and it turned to be a lot cheaper that holds more weight. I think it cost around $100k and it held around 15 lbs. The key to making this bridge was that we didn't use any grooved pieces so we can try and make it pretty cheap. We will make more modifications to this bridge and we will probably end up using something similar to what we have now for the final bridge competition. I think the main fault in this bridge is that it follows the same pattern throughout the whole bridge and it is not reinforced in the middle so it might end up breaking down the center. Another problem is that we are unsure of how to improve the design of the bridge, since it held so much weight the first time.

I have learned a great deal about designing bridge from this class. One is that it is a lot easier to try a design out on the computer before you actually build it. This allows you to see basic outcomes as to where some of the pressure is building up on, so you can easily alter the bridge to dissipate the pressure. Another thing I have learned is that there isn't simply one good design that will win the competition. Since the competition relies on the weight/cost ratio, there are many ways to try and win. An example is that you can go for a very heavy bridge that holds a lot of weight, or the opposite, which seems to be more effective. Hand-calculating the pressures on the bridge is possible and is very important if there isn't a computer program that can do it for you as it can take quite a lot of time.

Skip Week 8 Blog Entry

The prior week, we started the analysis of the truss bridges. We used laws of physics and conservation of energy to calculate how the force of a load on a bridge is dispersed throughout a truss bridge. By doing so, we were able to calculate the tension and compression on the individual members of a truss bridge. We also made small modifications to the bridge and plan to further improve it. The coming week, my teammates and I agreed to make final modifications to the bridge to get it ready for the final weight load test. The major accomplishment this week was that we we able to learn how to analyze a truss bridge and how forces act on the bridge. Using this knowledge, we can improve our bridge and make it stronger. The major problem is that the bridge seems to be a little weak. My teammates and I have to work on the bridge to make it stronger.

This method of analysis is somewhat sufficient for a real bridge. It is somewhat sufficient because it uses actual laws of physics and you can see how the force of a weight on one point disperses throughout the bridge and you can see the tension and compression forces on the individual members of the bridge. The problem is that this only thinks about forces on one point. A bridge will have weight throughout the entire span and not just one point. The loads the bridges hold are not hanging straight from the gusset plates. It also disregards other factors such as wind which is very likely in real life. Another reason is that this disregards the weight of the bridge itself which will surely change the values. For these reasons, the analysis is sufficient to some extent.

For further analysis, I would like knowledge about the bending of the members. The analysis talks about tension and compression, but I do not know when the members would break. You could have a perfect bridge that holds a great amount of load, because it is strong against tension and compression but  I think that bending and breaking is another story. I would also like to learn about twisting. This is another factor that will affect the bridge. If I have all this information, I think I could do a legit analysis of the bridge.

Disel - Week 8 Blog Entry

We started working on our A3 assignment in our lab but the time was not sufficient to finish it. DJ  gave us really helpful instructions on how to calculate the tension forces for each point. We are also working on our final bridge design. The one we had before was a really good design but we have to change it because of the new restriction of 3" x 2" tunnel inside. Anyway we are doing good and I believe that in the end we are going to have a really good ratio weight/price.

The method of analysis is the first step in designing a real bridge but is not enough.This method just tells us how much weight the bridge is going to hold but it doesn't take in consideration earthquakes or wind effects. I think that to design a real bridge a lot more steps are needed but the one we are working on it should be the most important one.

A3 - Minami

In order to make the results of the hand analysis correspond to the online bridge designer, I had to scale the bridge side equally. In the hand analysis, the height of the bridge was 8", the span of the bridge was 24", and the weight at the middle point at the bottom was 15 pounds. In the bridge designer, I made it so that each grid spacing was 2" so the height is 4 spaces high, and spans a length of 12 spaces, and the weight remains the same so it is still 15. The bridge I made on the online bridge designer and the bridge of the hand analysis have a ratio of 1 to 2 respectively.


Knex Truss

I might use this type of analysis to improve the design of my bridge by looking at which parts of the bridge has the most tension and compression. Given the values for the pull-out force of the Knex, I can look at the online design and look at where the forces are greater than these values and see where I need to improve. I can also play around with the load and see how much weight can be held with the current design. This analysis will allow me to look at the individual parts of the bridge and which will allow me to modify the bridge part by part, and overall improve the bridge with best efficiency.

A3 - Spahija

 1) Calculations

 2) Results on the Trusses:
        Truss AB has -131.87 N
        Truss AC has 88.24 N
        Truss BC has 131.87 N
        Truss BD has -176.48 N
        Truss CE has 88.24 N
        Truss DC has 131.87 N
        Truss DE has -31.87 N

 3)

4) The results I calculated are relatively close to the results from Online Bridge Designer. My values differ from the program with 3% due to inability to define specific lengths and angles on the Online Bridge Designer. 

5) The best advantage that software has is that is a lot faster in calculating the value although they may not be 100% correct.

6) Now that I know hot to use the Bridge Designer I can test a lot of designs in a short amount of time and also find the place where the designs may be weak and try to fix them. The program shows me that most of the force is being placed in the middle of the bridge and there is where it need improvements. I think by dividing the big triangles into smaller ones might help distributing the force better.

Jonathan - Week 8 Blog Entry

Previously in ENGR-103, our group began to prepare for Assignment 3. We were initially confused as to what we had to do, but we managed to ask DJ for help and he put us on the right road to tackle this assignment. We also discussed a bit more as to how we will modify our bridge to meet the 3' mark and how we are going to add a 3" x 2" tunnel inside. A major accomplishment is that we have an idea for what kind of bridge we are going to bring in next week. We are still deciding between two very different designs, one being very lightweight and the other being sturdy, but requires more pieces.  The issue we have is working on the rest of the third assignment because it looks relatively challenging. 

The method of analysis we are doing for Assignment 3 is good for getting the bare basics down for a bridge's design. This does not factor in other variables such as wind, earthquakes and large amount of cars. Therefore, if you wanted to know if the bridge will stand up, then these calculations are all you need, but a real bridge has to do much more than that. If I could analyze further, I would probably try to get more information about the geography around the bridge. That way, I could see if it is in a very windy location, or if earthquakes are frequent, I can change the supports to match accordingly. 

A3- Fischer

1) Calculations

2) Results on the Trusses: (Positive is tension, Negative is compression)
Truss AB has -7.07 lb.
Truss AC has 4.99 lb.
Truss BC has 7.07 lb.
Truss BD has -9.99 lb.
Truss CE has 4.99 lb.
Truss DC has 7.07 lb.
Truss DE has -7.07 lb.

3)

4) Using the Bridge Designer is a lot quicker than doing all of the calculations by hand. However, it does have its restrictions such as only being able to add on loads in multiples of 5. An advantage of using the Bridge Designer is that it can scale the values of the length of all of the trusses or loads on a bridge. It keeps everything in proportion so if you want to create a larger bridge, all you would have to do is multiply each value until you get your desired number.

6) Now that I know how to properly use the Bridge designer, I can easily do many test runs to see which kind of pattern can sustain the most amount of load, while staying under the given "pill-out force" values. All that it takes are several guess and checks and see which bridge can survive while still not coming apart. The "Tensile Pull-Out Force" also shows that having three trusses connected to a gusset plate allows more force to build up before breaking. This can help us by making sure we try to add more connections in places that are weak.

Disel - Week 7 Blog Entry

Last week we were able to test our bridge. The bridge was able to hold 30 pounds of sand and it cost $243K. Even that our bridge was not the best I think that we got a good ratio in weight/price. We are trying to find out our weakest point of the bridge so we can make it stronger.  The main problem I think we had was that our length was exactly 2 feet and probably it should have been a little bit more so it would be more stable while testing it. We have to make the bridge 3 feet long for the final test so we are working on that. Based on the design of the bridge which is symmetrical I think that our bridge is still going to have a good ratio even after we make it longer.

For the Knex pieces I would like to know the tension force of each one of them. WPBD software tells me the tension of each piece so I am able to see where the bridge needs improvement. If I would know the tension forces for the Knex pieces I would play around with them to make the bridge cheaper and stronger since we already know the price of each piece. I guess by testing all of the pieces with how much weight they can hold before breaking like we do with the bridge, we can find out their tension force.

Skip - Week 7 Blog Entry

The prior week, our group was able to finally test out our bridge. The bridge for our group was a bridge that Diesel in our group designed, which was a under truss bridge. The bridge was able to withstand 30lbs of sand, and it cost about 250 thousand dollars. My teammates and I agreed to design our next bridge for next class. There are more restrictions in the new bridge. It must now span 3 feet instead of 2, and must have a hollow middle section that represents the part where vehicles can pass through. With these new restrictions, our group agreed to design a new bridge. The major accomplishment of this week was understanding what was good and what was bad about our bridge design. Our bridge was good because it was strong and firm in the up and down direction. The bridge did not bend or break during the test in this vertical direction. Our bridge was not good because it bent and twisted in a c shape which caused it to eventually break. We do not have any problems so we just have to think of a new bridge design that will follow the new guidelines.

For the Knex designs, I would like the numbers of compression (force/strength) and tension (force/strength) on the individual pieces and gusset plates. This will enable me to find out where there is most force so I could tell where I would have to reinforce. These numbers are shown in the West Point Bridge Designer, and using these numbers I was able to build a strong bridge on the program. In other words, If I have these numbers for the Knex bridge, I think I will be able to build a strong bridge that equally distributes the forces of the weight. I am already provided the price so I can play around with the bridge by adding or taking out pieces and seeing where the best balance is.

Jonathan - Week 7 Blog Entry

Last week, we got to test our bridge and compare the results to our peers' results. Our bridge was able to hold 30 pounds while costing $243k, which isn't so bad. We had to go through some nasty efforts to get the bridge on a level surface because the stilts had some grooves that made our bridge unstable. This week, we will continue coming up with designs to improve our current bridge, or try and think of a new design for the 3' bridge. An issue that we might have to face is the fact that we have to try and put a small 2" x 3" tunnel inside of our bridge, and our web interior doesn't allow us to do that.
If I was able to find any sort of numbers on our Knex bridge, I would like to find the stress buildup on all of the trusses and gusset plates. This way, I would easily tell which ones are strong, and which ones need to be reinforced. I wouldn't know an exact method, but I guess an easy way to approximate is to count how many connections a gusset plate is making and assume it builds more stress upon every truss. I would also like to have an easy way to count up all of the different kinds of trusses and gusset plates that are used within the bridge.

Disel - Week 6 Blog Entry

This week we worked on two bridges using knex. Skip and Jonathan worked on a design which was really strong and simple. I tried to do the same thing in but in a more complicated way. I used knex long bars in the middle of the bridge in order to make it stronger. Analysing the results the bridges seems really strong and not that expensive so we are gonna use them for our final design.

About the similarities and differences between the Knex and WPBD I would say that when we use Knex we work in reality (3d) so we can put things inside the bridge like I did putting long bars in the middle. In WPBD I cannot do that because when I do that it automatically is copied in 2 sides of the bridge. But on the other hand at WPBD we can use different bars in weight and length while in Knex this is limited.

Skip - Week 6 Blog Entry

The prior week, my teammates and I got to play around with the Knex pieces. We, as a group, made two bridges taking turns proposing what seemed to make the bridge stronger and better. Disel made a bridge that was very unique, and so he took it home to work on it further and make it hold more weight. I made a bridge that was very basic because it seems like a very strong bridge for its simple design. I brought it back to my room so that I could work on it further before class. This week, we will try to cut down the price and yet keep it strong. The major accomplishment this week was that we were able to design two bridges that will most likely be the basis of our final bridge. There are no conflicts as of now except that we must decide on best bridge design.

My view about the similarities and differences between the Knex and WPBD has not changed too much. The Knex pieces and an actual 20' bridge has different similarities and differences. A similarity is that both  the Knex and the actual bridge can hold stuff on it. Another one is that a real bridge and a Knex bridge makes uses of all sorts of designs such as trusses. A difference between the two is that there are only Knex pieces of a certain shape, whereas in a real bridge, there are all sorts of shapes such as hollow tubes and solid bars. The biggest difference I think is that the Knex pieces have to be a certain length, and the angles of the gussets must be a certain number. In real life, you can cut the pieces into whatever length you want, and you can connect them at any angle you would like.

Jonathan- Week 6 Blog Entry

Last week, we all got to have more time to experiment with the Knex. We took turns building the bridges we proposed for our second assignment and kept the two bridges that seemed best. Disel got to take his bridge back because of his interesting web design that holds the two planes together, and Soichiro brought his back because it seemed like it could hold a lot of weight for its size. Before coming back to the Week 6 Lab, we will all adjust these bridges and try to find the most efficient designs for them. There aren't really any conflicts at the moment, other than deciding whose bridge will be the best.

I don't think my opinion about the similarities and differences between the Knex and WPBD has changed. Comparing the Knex pieces to an actual 20' bridge is another story. Some of the similarities between the two are that they are both physically capable of holding load before our eyes. Another is that they both make uses of trusses and gusset plates. However, I think the main difference is that the Knex will serve as more of a model compared to an actual sized bridge. The knex also limits you the the sizes of trusses that you can use, and the angles of the gusset plates. You can not reinforce any of the connections on the Knex, which makes every joint as flimsy as the rest.

Spahija - Week 5 Blog Entry

This week we started to use k-nex in the lab. In a short amount of time we figured out how to work with them and started building our own bridge. In the end of the lab my lab mate Skip was able to make a bridge which was not a very complicated design and it was really strong. We didn't had any problems this week as a group. Each one of us individually is designing bridges in West Point Bridge Design so that when we can start building our own bridge we will have a lot of ideas and we might have figured out a lot of things about bridges until then which might help us to save time.

I think that there are a lot of similarities between the West Point Bridge Design program and the K-nex. The only difference is that in West Point Bridge designer we can work faster and can calculate the cost really fast. On the other hand West Point Bridge Design shows how much the bridge can hold, something that using K-nex we can't do because it takes a lot of time. Personally I think that we should work a lot more with West Point Bridge Design than K-nex.

A2 - Spahija

I tried to make a simple design for my bridge. My bridge is really cheap but does not hold a lot of weight. I can still try to make it stronger by making more triangles or dividing the big ones in smaller ones. I used 30 and 60 degree right triangles.

Skip - Week 5 Blog Entry

The prior week, we were able to actually start using the Knex and play around with them to get used to how they connect and how they work. Our group decided to start building our bridges out of the Knex pieces provided, and I personally was able to make a bridge that will be the base of my design.

My teammates and I agreed to continue working on our designs the next week using Knex. We hope to actually make a bridge and test it out. We also agreed to take the best parts of our individual bridges and combine them so we can make the best bridge. We will also start making improvements on our new bridge to make it even stronger.

The major accomplishment this week was that we were able to design our own bridges using the actual materials we will use in the competition. We were also able to think of designs of our own bridge so we can make improvements in the upcoming week.

There were no issues this week. We were able to work on our own designs while working together as a whole suggesting ideas on how to improve our bridges. I guess the only problem we have right now is making a strong bridge that is cheap and yet holds a lot of weight.

The similarities between the West Point Bridge Design program and the Knex is that the elevation of the bridge can look exactly the same. If I make a random bridge out of Knex, I will probably be able to design the same looking bridge on West Point Bridge Design. It will also work the other way around also, but this will only be true from the elevation view. It can look completely different in the plan view. For example, you can have cross sections at the top of the bridge but this cannot be expressed by the West Point Bridge Design Program. You can also have a third layer of the elevation view instead of just two expressed by the program. These will produce differences from the program to the Knex structures.

A2 - Minami

My bridge is shaped as the way it is because I wanted to make a bridge made of multiple triangles of the same size. I have a bunch of right triangles in my design because I think using them will make the strongest bridge.

My bridge is compromised by only multiple right triangles looking at the elevation, and made of only rectangles looking at the plan. 

The design of the bridge changed because in the previous one, I had triangles of different shapes and sizes, but in this design, I decided to make it simple and just use right triangles of the same shape and size. This may be a standard looking bridge but it has been used in the past for a long time in real bridges. Even though it is nothing fancy, I am confident that it will be a strong bridge.

From designing this bridge, I learned that the most standard bridges may be the best bridges around. It is not fancy with arcs and circles, or curves, but it is a strong standard looking bridge that will do a good job. A standard bridge like this one with triangles and squares is a design that have been used in the past and will surely do a good job.

Jonathan- Week 5 Blog Entry

During our lab session this week, we finally got to have some hands on experience with the Knex. Throughout the whole period, the three of us decided to get a feel as to which pieces we could use and how they can come together in efficient patterns. Shortly after experimenting for a while, Soichiro was able to start a bridge design using the Knex, so Disel and I decided to help him create it. When the lab ended Soichiro got to take his bridge home but Disel and I still have to create one for ourselves.
WPBD vs. Knex
Similarities: They both offer the option to place trusses of various sizes and gusset plates to hold them together.
Differences: Knex allows us to build into the third dimension and actually have a hand on feel to what feels sturdy or not. WPBD gives us exact numbers of the stress that is on each individual member. Knex limits us the sizes of trusses we can use, while WPBD will use any truss length to connect the gusset plates. In WPBD, you can change the size and material of every truss, which will affect the total cost of the bridge, but Knex don't have that variation.

A2- Fischer

I went through many variations of the same bridge, trying to get it as close to 24 inches as possible. This is as close as I can get it while still sustaining a symmetrical shape. At first, I tried to follow the "Pratt Template" from the West Point Bridge Designer, but later found out that the pieces were not correctly sized to do so. 

Elevation (Side View)

My bridge comprises of 5" and 3.375" trusses. The diagonals are at 5" at 45 degrees, which are the only angled pieces in the bridge. The vertical and horizontal members are 3.375". The circles represent the gussets that connect the trusses. Ever circle is going to have 2, 180 degree grooved gusset plates, which allow the bridge to take a three dimensional form. 

Plan (Top View)

The top portion of the bridge shows the internals, or the web. It is fairly simply in my bridge, every gusset will have a 3.375" truss going in an orthogonal direction. 

Front View

This front view shows that this bridge does not contain a web.

Bill of Materials

Like I said before, this bridge went through many changes to try to get it to the correct size. I spent most of the time trying out the different sized trusses to see which ones will make it symmetric, but still in the ball park around 24". I was not able to make a cross section in the middle of the bridge (due to not having the correctly sized pieces), so I decided to add another "section of trusses" to one side to make both sides even.  I learned that planning a bridge without literally seeing the materials can be tough because you don't know what can fit where.