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Lags in Holdowns

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I just found out that a contractor substituted lagged HD5As for the
spec'd HTT16 shearwall holdowns.  Capacity works, but I'm not sure about
the lags.  I never spec bolted holdowns because the deflections are so
high, but I haven't thought about lagging them.  Simpson catalogue says
"Lag bolts will not develop the listed loads."  They will, however, help
with the deflection issue, and after what we learned in Northridge that
seems like a good thing.  How do lags really perform under cyclic
loading, particularly when put into a double 2x column?  I know the NDS
values are going to be < 1/2 to begin with, and with p/8D = ~0.6 it's
going to get worse, but what about the more practical questions:  does
it behave like a bolt, as far as lateral yield modes? Does it rock back
& forth and then just pull out?  

These are the questions that make me think my company should have our
offices in a warehouse with a full lab w/ shake table, so that at this
time on Friday afternoons we could stop work, crack a few beers, and
answer these questions for ourselves. 


Gordon Goodell





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