Ned Pelger's blog on construction, design and other weirdness. Email him at ned@constructionknowledge.net
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CONSTRUCTION KNOWLEDGE BLOG
August 25, 2008
Building Against the Forces of Nature
When all those schools collapsed in the recent Chinese earthquakes, reports emerged that the construction was sub-standard. The buildings simply weren’t built to withstand the predictable loads. I think it’s a great asset for Construction Supervisors to understand the basics of structural loads and structural design. Many times the Construction Supervisor will be the only person that catches a mistake that could lead to a future building collapse.
A few years ago we had some tornadoes pass though our area, I went to see a relative’s pig farm building in which the roof was completely lifted off the walls. Everyone was talking about an Act of God but I saw that no truss tie-downs were used anywhere on the structure. The framers had only toenailed the roof trusses into the top plate of the wall. A predictable wind load would cause this failure every time. The framers and the Construction Supervisor just didn’t understand the power of wind uplift.
While it’s difficult to see the power of wind, the following video shows some waves in a storm that give a great sense of what wind loads would look like. It’s a great representation of a force of nature.
[youtube=http://www.youtube.com/watch?v=oNpH5tx4Pu8]
As you walk around the jobsite, try to remember that this building will see some crazy loads in the next 100 years. Try to learn the basics of structural design and be the last check to make sure things are built right.