Most of the bridges similar to this design did not have the additional diagonal bracing from the top to the bottom chords. I think this basic design is a good example of trying to figure out a problem without boxing yourself into thinking of only typical bridge designs. This design takes what you have to do and does it very simply. Most of the time, simple is better.

It is pretty easy to see how this bridge failed: the bottom fell out. This is a fairly easy fix, and might have been due simply to poor wood selection. Had I paid more attention to the quality of wood I was using, this failure might have been avoided.

I used two pieces for the arch. I had a square 1/16″ x 1/16″ piece of Basswood for the bottom of the arch. Then I glued a rectangle piece of Balsa wood on top of that to form a T beam. This method worked pretty well, but Balsa is harder to bend than Basswood.

Although it took me 12 hours (whew..!) I could see the good result! It held 15kg!

I saw some other members’ bridge and recognized that the height and span things were different from our rule which is held in New York.

But there is one little problem. My bridge weighs 111g. I don’t understand why. I used balsa wood and bass wood both and only used 1/4×1/4 size. I think using only 1/4×1/4 is the main problem. I can’t upload the picture somehow, so I uploaded them separately. Please help me reducing the mass. Also, when I was
testing the bridge, there was a cracking sound. Can you tell me what that sound means?

It would be great to get advised from all of you.

I really have nothing on this bridge. I have no idea what team it is from, how much it weighed, or how well it did at the Science Olympiad competition.

I have a picture of it, well, because I had a camera, and the bridge was there. So if you have seen this bridge before, and have some info on it, I would love to hear from you.

I Beam Bridge

This was one of my earlier bridges. I built it after talking with my uncle, who is a mechanical engineer. He suggested that I try using an I-beam. This was a very good idea, but my construction skills at the time were not the best. In theory an I-beam is excellent for bridges, but I could not make it very well.

I don’t know how much this bridge weighed, but it did not hold very much weight.

I had problems making the two I-beams for this bridge. I had to cut my own strips of wood, and I was not very good at doing that yet. The wood I used was very thin, perhaps too thin. I believe I used 1/32″ x 1/4″ strips.

I could not cut the wood strips very straight, and that was the downfall of this bridge. The pieces to the I-beam were not glued together well at all. I was trying out some unique things with this bridge. And if I had better building skills, it would have turned out much better. In later years I was able to make good I and T beams which performed very well.

Boy does this bridge bring back memories. I built this bridge in 2001, in the 7th grade. It was my first attempt at building a bridge on my own after building this bridge with my partner.

I had wanted to make an arch bridge, much like the Booth Bridge, but I didn’t have the building skills to do join the arches in the middle. So I simply made an A frame bridge. I never knew how much it weighed as our Science Olympiad team did not have a scale back then. The bridge held about 30 pounds, just 3 pounds short of the magical 15 kilogram mark (33 pounds). Back then the Science Olympiad bridges had to hold the entire 15kg or they would be ranked in the 2nd tier.

This bridge was built only out of basswood, except for the roadbed. Even back then I understood the power of Basswood . I used Epoxy glue to build this bridge. That is because my bridge building coach used it, and I followed his example. I don’t use epoxy glue for bridges anymore, though I have used it for other things. Read more about choosing the right glue.

I was never able to fully develop and use this bridge. I got this idea from talking with a Science Olympiad coach in Ohio. Now I wish I had gone ahead and put more work into this. The next year, the bridge rules changed so that I could not use this concept.

The trick was to get the arches to the perfect length, so that they barely fit into the loading device. I had made these arches a bit too long. When I tested the bridge, the arches were already bent out-of-shape, so it did not hold enough weight. I fully believe that this bridge concept can go very far.

As you can see, this bridge had a roadbed, which was supposed to allow a hotwheels or matchbox car to roll freely across. BAD DRIVER!

Chamblee has always done well in Bridge Building. In 2001, they won the State finals in this event.

This bridge is from the 2003 GA State Tournament, the same tournament the Booth Bridge is from.

Yes, this is one of the coolest bridges I have ever seen. Built by J.C. Booth Middle for the Science Olympiad Georgia State Finals in 2003, it placed 3rd. For those of you who don’t know Booth, keep reading.

Booth Middle School has won the Georgia State Finals as a team for longer than I can remember, except for one year. They always have an excellent team, and provide much frustration and motivation for the rest of us.

When I first signed up for Bridge Building, I heard that Booth was the team to beat. So I made up my mind that I would beat them. Well, as a 6th grader and a newbie to Science Olympiad I didn’t know what I was saying.

However, I found out that Booth wasn’t the one to beat for Bridge Building. Rising Starr won that year with a 11.something gram bridge, holding 33 pounds. Chamblee won the next year, and E.T. Booth (not the Booth previously referred to) won in 2002. Booth, however, did win in 2003. This is not Booth’s winning bridge, just a cool one. Then all my hopes came true, when I beat everyone in 2004.

I actually have a picture of Booth’s bridge for 2005 (this year), and it is a nice one. But it didn’t win. Still, I might put it up, as the bridge rules have changed enough so nobody can use that design.

The boomilever broke because of all the force that was applied outwards on the bottom chords. The boomilever simply “split” apart and the loading block fell through. I didn’t anticipate the amount of force that would be pushing outwards. Normally my boomilevers broke at the joint to the attachment base. I later tried to add additional bracing but the boomilever never held more than 10kg. I think at the end of the season I was close to an efficiency score of 1000. My team didn’t make it past regionals that year, so I didn’t have a reason to try for more.