[Towertalk] structural assumptions// rope--bolts

[Jim Lux]

> *  Bolts specified for racecar use are NOT necessarily stronger
> than or appropriate for tower use.  They MAY be; it depends on what
> they were used for.  You need to know the specs to know.
>    My personal recommendation is to go with Rohn galvanized hardware
> everywhere.  Zero doubts.  Zero rust.  Worth the price.

Higher strength bolts can also be stiffer, and can actually take more of the load as a
result.  I would imagine that the average tower isn't a "ragged edge of material
science" design, but, the designer does choose bolts according to their stiffness and
stretch under load. In the racing world, some have found that putting stronger bolts on
the cylinder head or main bearing caps just makes the engine fail sooner because the
bolt's not "absorbing" some of the force.

Bear in mind also that counterfeit bolts (low quality, but marked as higher grade) are
moderately common.  Not that I'd want to see "traceability to iron ore" documentation,
but I'd be a bit suspicious about high strength bolts being sold cheap out of the back
of a truck. At least if you are buying from a "reputable" dealer (i.e. one that stands
to lose a bunch if they are found liable for selling counterfeit goods) the bolt marked
Grade 8, probably really is.

High strength bolts (fasteners in general) ARE expensive compared to the "butter steel"
stuff for the price sensitive buyer in the bins at Home Depot.

You've gotta decide... is my life/house/etc. worth saving a few bucks on a cheap bolt.