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The Destruction: Engineer in Training Open Web Level Two Blog: Part IV

Posted on August 02, 2012 by RedBuilt


by Jason Fitch, Engineer in Training at RedBuilt™ [caption id="attachment_412" align="alignright" width="300"] The aftermath of testing: the sixth web buckled at the profile (far left) which caused the top chord split at the third pin (top middle) and the fifth web to pull out (middle left).[/caption] To test the Open Web Truss, we set up load cells at the ends of the truss and applied load uniformly across it. As load was applied, we could see the truss deflect. Failure occurred when the sixth web, a compression web, buckled at the profile. This caused the top chord to split and the fifth web to pull out. This was not the web I had predicted to fail (the next compression web ended up failing). The truss failed at 324.3plf which was approximately 10,216 pounds combined reactions (I predicted 328.4 plf and 10,345 pounds combined). Reflecting back, I had a great experience with the Hillsboro associates and learned a lot on the trip. Not just about the mechanics of building a truss, but the people who do it. I learned how my design can affect their efficiency as well as what they have to go through to ensure the final truss will be “as designed”. I have also come away with a new respect for them. In the four hours I was there building my truss, I made two mistakes that required things to be redone and fixed. In that time, these associates built multiple trusses without anything needing to be redone. Day in and day out, these associates work hard to build trusses fast and keep the same quality in each product they manufacture. Based on what I learned, they make it look easier than it is. I would like to thank Guy Brousseau and Rex Flegel for the training opportunity they provided for me. Thank you to Mark Scarlett for letting me disrupt his plant and using the equipment and material in order to build this truss. A thank you also goes to Ed Medley for taking the time to walk me through the process, the patience he showed as I made mistakes and the direction he gave me to help to remedy them. Also, thank you to Dwaine Charbonneau for the help in setting up and conducting the test.


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