I have built three different models of popsicle bridges. You can check out each one:
Popsicle Bridge #1
Popsicle Bridge #2
Popsicle Bridge #3
Popsicle bridges provide a unique challenge because of the limited length of the popsicle sticks. This hurts the inherent strength especially in tension. Ideally, a member of the bridge in tension would be one [...]

Science Olympiad is bringing back the Bridge Building event in 2009, except in a modified form. The event for ‘09 is Elevated Bridge, which will provide an interesting and refreshing challenge. The draft rules that soinc.org are very interesting and make for a good read. Check them out as the new bridge event looks to [...]

Upon request, I have written an analysis of the K Truss which you can read about on my truss design page. The K truss design deserves your consideration as a bridge builder.

Probably the question I get asked the most is “What bridge design holds the most weight?” or “What bridge design is the strongest?”

The answer to that question is not simple and probably is not going to be what you expect. The truth is, I cannot answer the question. There are too many variables that [...]

Built by Bill H.
Here is the email Bill sent me:I started making bridges about a year ago and have pictures to share with you. For the first bridge I used a set of plans that I found free on the internet from a guy who was in the army. The bridge plans were [...]

Not all popsicle sticks are equal

If you have been given a project of building a popsicle stick bridge, there is something you should know. Probably one half of the popsicle sticks that come from Wal-Mart or other store are bent, twisted, or otherwise deformed. And obviously deformed popsicle sticks won’t be as strong as straight [...]

Pictures taken on October 5, 2006.

From the east — The south truss
Underneath looking west — Underneath looking east
The south side again — The west truss

Links about the Greentop Road Bridge:http://bridgehunter.com/ga/coweta/7750080/

There are several reasons you should cut your own strips of wood:

It saves money
It saves time
Helps you get familiar with the wood
Increases your skills as a builder

Video Tutorial

Video is about 4 minutes long.

DISCLAIMER:
I am not responsible for any injury caused by someone using this technique. I recommend that students cut strips of wood [...]

Now Updated and Expanded
Now you can download the 5 Steps to Building a Model Bridge PDF ebook. The ebook contains the expanded version of the outline below, plus a lot of helpful pictures. The ebook also contains 25 bonus tips.
Here is a condensed version of the table of contents:
#1: Know the rules!

Be able to define [...]

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 [...]

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. 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 [...]

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 [...]

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 [...]

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 [...]

I just found some old pics of my first ever Science Olympiad bridge. This photo is 7 years old. Many props to my mom for keeping it.

Left to Right:My coach, David, Me
The bridge weighed 58 grams if my memory serves me well. It held the entire 15kg with ease. It probably could have held 100lbs [...]

Lateral What? Exactly. Perhaps the most important aspect of your bridge and you aren’t sure what it is.

Lateral bracing is the term I use to refer to any pieces on a bridge that help keep the top chord from bending horizontally. In the figure before, lateral bracing is red:

Why is lateral bracing so important?
As you [...]

Today I found out that the Whooping Creek Bridge on Clem-Lowell road has been reopened. This was good and bad news for me. My brother and I drove down there this morning to try and film something for the music video we are making (see previous post). We thought it would be the perfect place [...]

This bridge was definitely not my best, but it does bring back memories. It was the second bridge built by my old Science Olympiad Bridge Building partner, David, and I. As you can see, we were still in the beginning of our bridge building career. I assume David is still building bridges, as his father [...]

The Whooping Creek Bridge was originally built in 1928 (According to here). Unfortunately, the bridge was closed in May of 2006 after a DOT inspection. 5 months later, no work has been done on the bridge. From what I understand, there is division on what to do with the bridge. Some people want to replace [...]

This balsa bridge was built by some students of mine. It spanned 14 inches, weighed 8.1 grams, and held 29 pounds. That puts its efficiency at 1630.

This photo makes the bridge look a little lopsided. That wasn’t the case, however.

Here is a photo of where the bridge broke. Click the picture to get a really [...]

I have become enamored with the idea of building a suspension bridge. I am not exactly sure why, and I also need to finish my toothpick bridge. However, I have begun thinking about how I would go about it.
A suspension bridge would be the most difficult challenge so far for me. I am thinking as [...]

How Changing Height Affects a Bridge
I found it slightly difficult to come up with the right title for this post. Perhaps a better one is What happens when you change the height of a bridge assuming nothing else changes. I am talking about the forces that act on a bridge, of course.
I get asked all [...]

I have never built a toothpick bridge before, as I thought it would be too much of a hassle. However, when I came across a toothpick bridge kit I knew it was time for me to try building one.I purchased the kit, and am very pleased and surprised at its contents. The kit contains everything [...]

Here I have complied what I believe to be the best list of websites that you will find useful. All of them have relevant model structure, bridge and tower information, some sell balsa and basswood, and others contain useful tips. Some of these sites have a specific competition or goal in mind, but you can [...]

If you have visited my Projects page, you probably have seen the Fernbank Bridge. It is coming up on a year since I built that bridge. Original Fernbank Bridge Which means, it is about time to build a sequel. Unfortunately, the date for the Atlanta Toothpick Bridge Competition (where I test the Fernbank Bridge) and [...]

This bridge was built by Michael in Quebec.
I have a bridge I built for a physics for engineers class I’m taking in cegep (QUEBEC). My partner and I didn’t have much confidence in it, but it blew the competition away! The design was a fairly straightforward arch as you can see. We primarily focused on [...]

1. Humidity affects the weight of your bridge. Keep your bridge in a closed container with a few grains of rice.
2. Go easy with the glue bottle. As a general rule of thumb, if you can see it than you are using too much.
3. Keep your hands clean! Oils and grease from your skin [...]

This bridge won the 2004 GA State Science Olympiad Bridge Building competition. It weighed 9.47 grams, spanned 35cm, and held 15kg without breaking. The efficiency score was 1584. This bridge was made completely from Basswood. No Balsa or other wood was used.

The top chord was made from 2 sticks of 1/16″ square pieces, [...]

An L-beam is more efficient than a square the same width. It is not going to hold as much, but it is going to be more efficient. An L-beam is also more efficient than a square with the same mass of wood. Of course, you have to count in the glue weight for an L-beam.Balsa, [...]

Compression:
Compression is a pushing (compressing) force. You can take the middle a straw and squeeze it between two fingers, the straw flattens. However, if you hold each end of a straw and push together it is harder to make the straw compress, or flatten. The shorter a piece of wood is, the more compression it [...]

Question:
What’s your take on the new scoring. Do you think the bridge should just aim at holding 15 kg… or try to build one that’s lighter and hold less possibly getting a higher efficiency score?
I used to think that you should go lighter, holding less. But now I think that you should aim at [...]

The type of joint you use on your bridge can drastically change its strength.
Lap Joint:

The lap joint is one of the strongest, and you should use it whenever you can. It strengthens compression members because it adds stiffness. The lap joint has one drawback, however. The joint is only as strong as the face of [...]

What is the coolest bridge on the planet? This is one of them:
Coolest Bridge

I still love Scotland’s Firth of Forth bridge, and the famous one from my birthplace, the Golden Gate bridge. But that one that connects Sweden and Denmark is pretty cool! I wonder what it feels/sounds like when going under the water. It [...]

I built this bridge for the 2005 Fernbank Science Center bridge design event. This is the strongest bridge I have ever built. The bridge spanned 16 inches, weighed 37 grams, and held 346 pounds. That puts its efficiency over 4200! I had never even come close to getting this amount of strength out of a [...]

Many people come to GarrettsBridges looking for advice on building a toothpick bridge. And though I have thought much about it, I have not attempted to build one yet.

This is a Japanese toothpick bridge contest. You will find tips on how to make them, as well as pictures.
Toothpick Bridge Building Contest
Here is a father who’s [...]

Common trusses used in engineering:
Warren

Pratt

Howe

K Truss

The following figures are shown under a load. The numbers represent percentage, where the total load = 100. The numbers are rounded to the nearest 5. For absolute numbers, visit the Bridge Designer.
Red represents tension, blue represents compression, and green is no load.

On this Warren truss, each of the [...]

I have developed a system for bending wood for my arch bridges, and though I do not claim it is the best way, it works well for me.

I have a pot, or basin rather, that is about 18″ long and 12″ deep. I fill it with about two cups of water (I have found that [...]

There are several ways to test model bridges:

With a machine
By pouring sand
Textbooks
Pushing down on your bridge

Using a machine

Obviously, if a machine is being used to test your bridge, there isn’t a lot you can do. You can stand watching the destruction of your bridge. Or turn away and cover your eyes with your hands. I [...]

I was first introduced to the Bridge Designer by a civil engineer, who explained to me the usefulness of the free program. However, it took me, a 6th grader at the time, over a year of playing around with it to finally figure it out.
Link to the Bridge Designer
The Bridge Designer allows you to create [...]

What you want to look for in glue:

Drying time
Price
Weight
Strength

CA Glue. This is a very common glue used for a variety of projects. It dries in seconds, like super glue. It is also widely available. Numbers of hobby stores and online companies sell it. However, it is not cheap. CA glue can be bought in three [...]

I am constantly asked whether balsa is better than basswood. Here are some of my notes comparing the two woods.
Balsa is cheaper and more available than basswood. This means you can buy more wood, and build more bridges for the same amount of money. By building more, you will gain valuable experience and improve your [...]