Welcome to our Structural Engineering Blog! I’m Paul McEntee, Engineering R&D Manager at Simpson Strong-Tie. We’ll cover a variety of structural engineering topics here that I hope interest you and help with your projects and work. Social media is “uncharted territory” for a lot of us (me included!), but we here at Simpson Strong-Tie think this is a good way to connect and even start useful discussions among our peers in a way that’s easy to use and doesn’t take up too much of your time.
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Code Development: The ASTM Process
I spent a few days last week traveling to attend the Spring ASTM International meetings held in Phoenix, AZ. When I was working as a building designer, I always used ASTM standards in my project specifications or testing and special inspection requirements on a job. But I did not know how these ASTM standards were developed, nor did I know that I could participate in the process.
ASTM standards are voluntary in the sense that ASTM does not require their use. However, since ASTM standards are referenced in building codes and design standards that are adopted by states and local jurisdictions, compliance with those standards is required. So it might be useful for structural engineers to know a little bit about how these standards are created.
Designing Light-Frame Wood Structures for Tornadoes. It Can Be Done!
Being from California, I had always bought into the common misperception that wood light-frame construction can’t be designed to resist tornadoes. While it is true that debris impact can’t be cost-effectively designed into residential structures, there is a lot that can be done to strengthen the structure and protect the occupants inside. Using the same technology common in hurricane-prone regions, these buildings can protect people for more than 95% of reported tornadoes.
The effect of tornadoes on wood light-frame structures has been extensively researched over the last few years, and researchers agree: A strong, continuous load path is essential to minimize destruction.
Do You Design with Wood (Shrinkage) in Mind?
Wood is a unique building material because its characteristics are dependent on the environment and its moisture properties, which can vary over time. Often, sawn lumber
is delivered to the jobsite with relatively high moisture content. Over the life of the building, moisture content will decrease until equilibrium has been achieved. As moisture content drops, the wood members shrink. Most wood shrinkage occurs during the first six months of the building life and it’s an important design consideration.
But I Don’t Design Cold-Formed Steel…
For the first half-dozen years of my professional career, my experience with cold-formed steel (CFS) consisted of sizing studs for non-structural walls and red-marking the bracing details on architectural plans. When the dotcom bubble burst, my firm needed to shift its focus from high-tech commercial and industrial to more multifamily design work. Several developers we worked with built with CFS, so in addition to designing condominiums instead of cleanrooms, I was designing CFS.
Less than 10% of engineers have any exposure to CFS design as part of their undergraduate education. OK – so this is based on an informal survey of about 50 colleagues, but I suspect if I were to hire a market research firm for lots of money, I’d pretty much get the same response.
