Comments on: Truss Design

By: Cat

Cat — Fri, 04 Jan 2008 01:30:35 +0000

We are doing a bridge project in technical drawing. We have 8- 600 mm peices of balsa wood that are about the width of a plastic bendy straw. Probably a tiny bit bigger. The bridge has to be 250-300mm in length, 50-75mm in width, and less than 100mm tall. The roadbed needs to be 200-300mm in length, 50-75mm in widthe and less than 50mm tall and an underhang is opptional (this will depend on the type of truss obviously) The underhang must be less than 180mm in length, 50-75mm wide and less than 20mm tall (this includes the overall height of the bridge). To test the strength, our techer is putting a disc in the middle with a hollow rod in the middle of that. The pole is attached to a bucket and weight is going to be added to the bucket untill it breaks. Anyways, I am the only girl in the class and I feel like I am constantly needng to prove myself (eventhough half of the guys in there are complete idiots). I know that general triangles are the best shape to use. Do you have a recommendation on what type of truss I should use? I was thinking about a pratt or a howe truss but feel free to suggest something else. Thank you so much!

By: Katarina

Katarina — Thu, 03 Jan 2008 03:41:24 +0000

What bridge is best to use for a science fair project to test the strength?

By: Garrett

Garrett — Fri, 28 Dec 2007 22:19:47 +0000

Thanks for pointing that out, Spencer. BTW, sorry for the delay in getting your comments up. My comment SPAM filter was blocking a lot of comments and I didn’t realize it.

By: Spencer

Spencer — Thu, 27 Dec 2007 21:45:45 +0000

The K truss holds the most vertical force for a bridge loaded in the center (which is the case for most bridge design contests). Go to the bridge designer and compare force distribution on a K truss to what you see with the Pratt or Howe. You will find that the K truss distributes the load much more evenly and efficiently, unlike the Pratt and Howe trusses which frequently have individual members supporting as much as 115% of the load. The bridge I’m currently building uses a K truss design and no member has to support more than 50% of the load.

By: actual design

actual design — Thu, 27 Dec 2007 07:51:21 +0000

I would like to see the actual design of concrete bridge.

By: Sean

Sean — Thu, 20 Dec 2007 22:36:09 +0000

I was wondering if there was a bridge design, that if a verticle weight was hung from the bottom of the bridge, would be most efficient?
Is it even necessary to build a top portion or will a simple horizontal base be suffuicient?

By: Dick Marsden

Dick Marsden — Thu, 20 Dec 2007 00:42:30 +0000

I was thinking about the vertical supports, does that make it much more effective and stronger then haveing arches?

By: Sam

Sam — Mon, 17 Dec 2007 19:07:56 +0000

What is the best overall bridge design to build?

By: Erickson Brown

Erickson Brown — Mon, 17 Dec 2007 15:41:53 +0000

How would you know what the diffrences are between the diffrent bridges? If you would not mind would you type me a 3 page paper about the diffrences and how they work. that would be highly appreciated….

Erickson Brown

By: Jason Adams

Jason Adams — Thu, 14 Jun 2007 16:35:13 +0000

I was wondering which truss design would support the most vertical force if the force was place in the center of the bridge?