Model Bridge Design

Enjoy watching this video of a quickly made bridge that supports a lot of weight. It also includes video footage of the Ignite Seattle popsicle stick bridge contest.

GarrettsBridges.com is hosting a West Point Bridge Design Local Contest. This local contest starts today and runs to March 1, 2010. All designs must be submitted by Midnight, March 1. This contest is open to anyone under the age of 25

A well done introduction to the practical steps of truss design.
Written in 2004. It has 448 pages and has an average of 4.5 star rating on Amazon.
Contains Illustrations.
Here is the link to purchase this book at Amazon:
Design of Building Trusses (Parker/Ambrose Series of Simplified Design Guides)

THE 2010 WEST POINT BRIDGE DESIGN CONTEST IS ALMOST UNDERWAY! The United States
Military Academy is pleased to offer the West Point Bridge Design Contest once
again. The purpose of this Internet-based competition is to provide middle school
and high school students with a realistic, engaging introduction to engineering

This is a fun video showing the failure of a lot of Science Olympiad Elevated Bridges at the Crystal Lake Invitational 2009. Does anyone know what state this is held in? This video shows a lot of different bridge styles for Science Olympiad, so it might help give you a starting place for a design. Keep in mind that this is just at the invitational competition level

Here is a balsa wood bridge being tested to failure. You can tell how it breaks, which is pretty cool

Are you interested in building bridges for your model railway set? This book is a great resource, and is cheap from Amazon. This guide is rated 5 stars and will help you create bridges and tunnels for your layout. It will teach you how to build prototypes of many real life train bridges. What is neat about this book is that it gives you the history of the bridge you will be building. It is always fun to know the story behind the structure you choose to add to your set

Video of a large Pratt truss bridge being loaded to failure

This video has some excellent toothpick bridges. These bridges hold an incredible amount of weight before they break. You get to see it all on video

This kit is actually one of my first introductions to building model bridges. My mother bought this for me one year, thinking that I might like to build a model bridge kit. This bridge building kit from Amazon actually has three different bridges. It comes with all the supplies you need to build a suspension bridge, a truss bridge, and an arch bridge. All of these combined make this kit an excellent gift idea, or something you can build just for fun

The annual summer itch to update my website has struck again. This update is mostly a frontend, visual update. The website should look much nicer and cleaner now. A bonus of this is that it should be easier to tell where things are

I am always on the look out for good software to help design model bridges. My latest find, Dr. Software, is a series of programs that allow you to customize a design, put a load on it, and see what happens. Dr. Truss comes in 2D and 3D options. You can also get Dr. Beam, which allows you to word with a beam and not a truss

Buy this engineering textbook through Amazon for the cheapest price if you need this for an engineering class.

This is the absolute best video I have seen about building model bridges. Roy Coleman, the founder of the International Bridge Building Contest, gives a very informative presentation in this video. The presentation is over an hour long. He shows how to build a bridge from scratch. He is gearing his video towards the Chicago Regional Contest in particular. The concepts, however, apply to virtually all model bridge building projects. This is a great companion video to my 5 Steps to Building a Model Bridge ebook

Here is the Science Olympiad bridge J.C. Booth built for the Georgia State Tournament in 2005. I don’t remember exactly what place it got, but am pretty sure in placed in the top 3. This bridges uses the typical design for that year, with slight modifications

Amazon.com Widgets

This is an older bridge I came across when browsing through my old Science Olympiad photos. I used both Balsa and Basswood to build this bridge. This bridge was part of my design process which ended up with my SO winning bridge in 2004

From Amazon:

Technical Details
NOTE: This is the 3rd generation 8 GB iPod touch that comes installed with iPhone OS 3.1 Software; it physically looks identical to the 2nd generation 8 GB iPod touch
IMPORTANT: To get started using your iPod, charge your player using the USB cable for at least 2 hours
8 GB capacity for 1,750 songs, [...]

Slim: Just over 1/3 of an inch, as thin as most magazines
Lightweight: At 10.2 ounces, lighter than a typical paperback
Books in Under 60 Seconds: Get books delivered wirelessly in less than 60 seconds; no PC required
3G Wireless: 3G wireless lets you download books right from your Kindle; no annual contracts, no monthly fees, and no [...]

I want to put x-shaped supports on my bridge, but I don’t know how best to join them. I’ve heard of something, I think it’s called a half-lap joint, that I think might work best. You cut half of the wood off the part of the strip that will be the actual joint, and then connect the two pieces at those joint parts. There isn’t any part of the wood sticking out, and they are very connected, I think, as far as how the weight/force is distributed, which I figured would be good. But is there a better way to make an x

This is a popsicle stick bridge I built while in the last few weeks of my fall college semester. I used 924 popsicle sticks to build this bridge. This bridge was 5 feet long, 10 inches tall, and 8 inches wide. I had to sort through 2600 popsicle sticks to find enough usable ones. The first testing of the bridge consisted of 220 pounds worth of weights. The second testing included putting a piece of plywood on top of the bridge and me standing on it (170 pounds). We noticed that one end diagonal chord was bending tremendously, so I decided to call off any more testing until I could repair that one piece

I have updated to the latest version of WordPress. If you notice any bugs around the site please feel free to share them. I will be spending the next several days finishing the upgrade

Here is a video playlist I created from youtube of selected popsicle bridge movies.

You can see a variety of testing methods used in these videos. You can also see a lot of people not wearing eye protection, which is not a good idea. Always wear eye protection when testing a bridge.

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.

After long last I have completed this music video of the song, Bridge Builder Blues.

To see the lyrics of this song, click here

My brother, cousin, and I were inspired to make this spoof of the TV show, Man Vs. Wild. We call this Man Vs. City. It is filmed mostly on the Arthur Ravenel Jr. Bridge located in Charleston, South Carolina.
Man Vs. Wild is a show where a man, Bear Grylls, is dropped off in various wildernesses [...]

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 are [...]

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 [...]

This bridge is the Arthur Ravenel Jr. Bridge which is over the Cooper River in Charleston, South Carolina. It is North America’s largest cable stayed bridge. I got these photos when visiting family up there.

My brother, cousin, and I filmed a short spoof of the TV show, “Man Vs. Wild” [...]

I have always been fascinated by sailboats. I loved to visit my grandparents in Florida, because it meant sailboat rides.
This is not the first time I have made a little sailboat. But it is the first popsicle boat I have made.
I started out using only the “reject” popsicle sticks that I would not use [...]

Many people ask “Where is the the best place to buy balsa wood online?” The best website I know of is Specialized Balsa LLC. The owner, Jake Zimmer, has been in the balsa business for years and knows what he is doing. Once I had Jake cut me some 1/32″ x 1/32″ sticks of Balsa [...]

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 [...]

The fix for IE6 took a while, but in the end was simpler that I anticipated. I have already updated the homepage, and the rest of the site will follow shortly. If you are running IE6, please confirm that everything looks okay.
I am still working on a new and greatly expanded photo section.
Work on the [...]

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/

Have you wanted to make a strong popsicle stick bridge that used 100 popsicle sticks or less? This popsicle bridge was made from 98 unmodified popsicle sticks and WeldBond glue. It was 21 inches long, 4 inches tall, and 4 inches wide. It weighed about 150 grams, and held 140 pounds. With less than 100 [...]

This popsicle bridge was made from 58 unmodified popsicle sticks. It was 25 inches long, 4 inches tall, and 3 inches wide. I used only Elmer’s white glue to build the bridge. It weighed 86.5 grams, and held 45 pounds. Its efficiency score was 248.
Build This Bridge

I redesigned this bridge from the earlier version. [...]

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 only [...]

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. 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 [...]

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 [...]

The famous Relpats Contest has been reborn. Simply go to www.relpats-eht.com to check the contest out. Unfortunately, I have been *sniff* forbidden *sniff* from the contest as relpats had already sent me some of the answers when the contest was in development.
These riddles will probably leave you scratching your head from absolute bewilderment. And no, [...]

I think it is time for me to build a popsicle stick house. I have built plenty of popsicle bridges, and even a popsicle boat. This collection would not be complete without a popsicle house.

I think I am going to stay simple with the design of the house. No fancy roofs or windows. Perhaps I [...]

The Bridge Builder Blues is a fun little song I originally wrote back in late 2004. I forgot about it until the Science Olympiad season of 2006. I pulled it out, and with the help of my brother re-wrote the lyrics and came up with the music. Then in 2007 We made a music video [...]

Someone tipped me off to this cool bridge which is in the Grand Canyon:
The Skywalk

It looks a bit scary but very cool nonetheless.

Now that the 2007 Science Olympiad season is well over, I am releasing photos of a concept boomilever I made before regionals. Here is a video of the testing of the boomilever:

The boomilever broke because of all the force that was applied outwards on the bottom chords. The boomilever simply “split” apart and [...]

Objective: To build a boomilever with the greatest efficiency.
Basic Design:
There are two basic types of boomilevers. First is the tension boomilever, where the tension chord is longer than the compression chord.

Second there is the compression boomilever, which is the opposite of the tension.

It is generally accepted that the tension boomilever is inherently better than the [...]

Balsa wood is unique from all other woods. Its properties make it valuable to bridge builders, wood carvers, surfers, and many others.

My favorite article about Balsa wood was taken down, but I found a copy of it at Archive.org.
Balsa or Basswood?
I have heard a lot of people claim that nobody should use Balsa. They claim [...]

The 2007 contest is over, check back next year for another chance to win!
Here is the Local Contest’s winning bridge:

This is not the winning design for the worldwide contest, just the GarrettsBridges.com local contest. Congratulations to Big Jake who submitted the design and won $100.
Link to Scoreboard

Website version 5.2.0. has been officially released. Hopefully there are no bugs, but that is too much to ask. Nonetheless, I did simulate the environment before I went live, so there should be no major problems. The main page has changed significantly. I think the sections are spaced out more, and are now more clear. [...]

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 [...]

I have almost finished work on version 5.2.0 of GarrettsBridges.com. The new version includes a fresh look, improved navigation, and the start of an enhanced photo gallery.
I have also completely changed the backend of the site. The header, right nav bar, and footer are all going to be PHP powered now, so making updates across [...]

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 [...]

Some friends of mine recently took a road trip to to PA. On the way, they stopped by a famous bridge and took this awesome picture:

Click for a closer view
This is the New River Bridge in West Virginia. It was the longest single-arch steel span bridge when it was built in 1977. In 2003, however, [...]

Blue skies and rainbows
And sunbeams from heaven.
Are what I can see when
My Lord is living in me.
CHORUS:Jesus is well and alive today,
He makes His home in my heart.
Never more will I be all alone since He
Promised me that we never would part.
Green grass and flowers,
All blooming in springtime,
Are works of the Master
I live for each [...]

The concept of stiffness is one I have been delving into this year. The stiffness of the wood you use directly translates into the strength of your bridge. Density no longer matters much, and is almost not worth calculating unless you can find a relationship between density and stiffness. I have not been able to [...]

Today I found out what exactly a pony truss is. I had heard the term before, but never understood what it meant.In fact, it is quite simple. A pony truss is a truss bridge which allows traffic through the truss, but the top of the bridge is not joined together with cross braces.
Example of a [...]

Yesterday (Nov. 11, 2006) was the Science Olympiad competition, the Westminster Invitational. This has to be one of the earliest tournaments in Science Olympiad. Normally the invitationals aren’t until January.
The boomilevers there were not impressive (including mine). Only one boomilever had an efficiency score over 200, which did happen to be mine. I placed first [...]

As I have been building this website, it has been my goal to get links from other model bridge related websites. I have spent a considerable amount of time doing this. It has paid off though.What is really cool though, is when other websites link to Model Bridge Design all on their own. And that [...]

Here is a picture of the George Washington Bridge that a friend of mine took recently.

I know I already mentioned this website in previous posts, but I felt this website was cool enough to deserve a post of its own. The coolest bridge website is BridgeHunter.com.
This website is simply amazing. James Baughn has created a website featuring historic bridges across the nation. Anyone can submit photos or comments about the [...]

Here is my first attempt at a game called Line Rider:

Line Rider is a free flash game in which you make a track for the “rider” to ride upon. It is fun and addicting. Have fun making your own LineRiders.

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 [...]

I was looking at my logs this morning, and noticed someone found my website by clicking a link from a Yahoo answers page. Curious, I went to the page. Someone was asking how to build a Popsicle Bridge. Two people had answered the question. The first person mentioned my website along with a complimentary description [...]

Recently I was introduced to a bridge building program, Bridge It. This program is made by NVIDIA and Auran. In the game, you are given scenarios and have to make a bridge that will support the required load while staying within a budget. Let me tell you, some of them are not easy.
Bridge It lets [...]

This is a quiz on bridges, how they work and the forces that act on them. It is rather simple, but is a good review if you are just learning about bridges.
http://www.sinc.sunysb.edu/Stu/ppoggio/
Click the Bridge Building link on the left. Then click the 4th link down with the big question mark next to it.

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 [...]

My first event was Circuit Lab, which I don’t know much about. My partner ended up doing most of the work, I helped connecting wires when I could.Rocks and Minerals went okay, or so I thought. Ended up with 7th.

My tower broke too soon, weighing 6.5 and only holding 6.8kg. At least I worried McIntosh [...]

Note, this page is meant for laughs only, and not to offend anyone. If I happened to use something you said, well, laugh along with the rest of us

yea…page 5 has no solution does it? ur just pulln my leg…its not possible i swear it isnt!
okay i got number one now a lil more of [...]

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 [...]

I am very excited to show off this new digital gram scale I ordered off Ebay.

This digital scale measures to 0.01 grams, which is a major improvement over the team scale, which only measures to 0.1 grams.The best part is that it only cost $20, shipping included. A hot deal if you ask me.

It seems [...]

Came across this today. Here is a scale model of the Brooklyn Bridge.
Brooklyn Bridge
The website has some other interesting info about bridges, including screenshots of designs for the West Point Bridge Design contest. BTW, that contest starts today. If you haven’t checked it out, do so now.
http://bridgecontest.usma.edu/
It is free, and lots of fun to play [...]

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 can [...]

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, [...]

This tower was 24 inches tall, 6 inches wide at the base, tapering to a 1 & 1/2 inch square at the middle. This tower weighed 7.0 grams, and held 11kg for 2nd place at the 2005 GA Science Olympiad State Finals.

I am in the middle of building a tower for my Science [...]

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 [...]

Here are some pictures of European bridges I took on our family trip in December of 2004. Seeing these bridges was the highlight of the trip for me. Unfortunately we only were able to drive over one of the bridges, the Tay River Bridge. However, we did spent a lot of time walking on the [...]

We had some of our cousins spend the weekend with us. After the initial greetings, Matt asked me, “Can we go finish the bridge?” We had started building a bridge last year, when they came over to visit. Matt had finished one side of the bridge. While I did help him design it, Matt did [...]

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 holding [...]

The Bridge Builder Poem
An old man, going a lone highway,
Came, at the evening, cold and gray,
To a chasm, vast, and deep, and wide,
Through which was flowing a sullen tide.
The old man crossed in the twilight dim;
The sullen stream had no fears for him;
But he turned, when safe on the other side,
And built a bridge to [...]

If you have read my bio page, then you already know a little bit about my bridge building experiences. But today I want to share some more behind why I created GarrettsBridges.com.The only reason I got involved in model bridge building was because of my activity in Science Olympiad. Before that, I simply had no [...]

The type of joint you use on your bridge can drastically change its strength. These pictures are not of glued joints, I simply laid sticks together. On a bridge, you want to make sure that the joints are clean and there are no gaps between the wood. Glue does not work well as a filler, [...]

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 [...]

Version 5.0.0 has been released. However, I cut out some of the new stuff. I will add that later.The major new section is the Bridge Photo Gallery. You can click on all the photos, and some lead to a page with more information about that bridge. All will show you are much larger picture, so [...]

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 [...]

You have probably noticed some changes on the website. Those are the new version, 4.5.2. What may not have noticed, is that only the homepage was ever 4.5.1. I didn’t have time to change the other pages, and now it is updated yet again. What exactly are the changes?
1. New position and style of the [...]

Build This Bridge
This popsicle stick bridge was made from 40, unmodified popsicle sticks. The bridge spanned 12 inches, was 4 inches tall and 3 inches wide. I used only Elmer’s white glue to build the bridge. It weighed 57.4 grams (0.13 pounds), and held 90 pounds. Its efficiency score was 712.

This was the [...]

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 [...]