Trusses

I need to know how to build trusses to make a bridge for a science project. How do I put them together to make the strongest bridge. I have to build a bridge 10 inches long and 3 3/4 inches tall out of wood strips that they give us. The supports need to be above the bridge. How do I build supports and make them strong?
- Beth (age 13)
Hamilton Southeastern Jr. High,

Dear Beth,

Thanks for your question, and sorry for not answering it sooner. Your question is a very good one, and is being studied by many engineering students here at the University of Illinois as part of their training. Unfortunately, it’s a difficult question to answer with just words, and a good textbook will better be able to show you (in pictures) what you need to know. I suggest looking in your school library.

As a rule of thumb, if you want something to be stable you want to make it out of triangular elements.



If you are making a suspension bridge, the same idea is true: You should include some diagonal braces to keep the structure from moving horizontally.



(The pictures are some I found from a lecture I have on "Statics", which is the field of study that this falls under).

(published on 10/22/2007)