- Kits and Plans
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 far as the actual construction. I have begun researching the design principles behind suspension bridges, and they are pretty neat. I have decided to […]
The K Truss design was a variant from the Parker truss design. The Parker, in turn, came from the Pratt truss. The idea of the K truss is to break up the vertical members into smaller sections. This is because the vertical members are in compression. The shorter a member is, the more in can resist buckling from compression.
Lateral what, you ask? If you don’t know what this is, you aren’t alone. In fact, it took me quite a while to understand how important lateral bracing is to the success of a model bridge, especially when striving for high strength or efficiency. Definition of lateral bracing Lateral bracing is the term we use to refer to any pieces on a bridge that help keep the sides (trusses) from twisting. It also helps keep the top chords of the bridge from […]
No Longer Available 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. The pictures in this post are from Dr. Truss 2D. […]
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, for some reason it seems, needs to be thick but low-density for pieces in compression. For tension, you have to worry about the face of […]
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 real pony truss bridge: Any truss bridge can be a pony truss. But not many are being made anymore, so chances are small […]
The Pratt Truss was designed by Thomas and Caleb Pratt in 1844. It became popular for railway bridges because it was able to have long spans. The Pratt has many variations, most with their own unique name. For instance, the Baltimore, Pennsylvania, and the Parker are all based off the Pratt.
This is the first in reviving my question and answer posts. When I receive a well asked question, I will answer it and post some of the dialogue here.
These two questions are dealing with making an elevated bridge, very similar to the Science Olympiad challenge.
Objective: To build a boomilever with the greatest efficiency. 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…
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 15, but no worries if it doesn’t. That rule gives a lot more freedom to builders, and now they can go lighter […]