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Re: OSHA Column Requirements

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This may sound odd but but if you need a pinned connection, you should either be using an actual pin or redesign the structure so that a partially-fixed connection will work.  Designing the base as a pure pin with two bolts where a moment exists could lead to a failure of the concrete base or of the anchor bolts due to the couple which will always be created at a bolted interface. Check the tension on your bolts with a heel-toe moment arm of the 3-4 inches you are probably going to get and see what the actual force is.  It's better to reduce the moment through other means than to analyze for a pin that can't (or, rather, won't) be built.

Accidental load paths are high on my list of reasons for failure, and it's worth looking at the overall system if you really need to have a particular end condition that is difficult to achieve.

Also, I think the ironworker weight is 300# (also from memory...don't quote me in front of the OSHA inspector).
Jordan


Robert Kazanjy wrote:


On 8/28/06, sscholl2(--nospam--at)juno.com <sscholl2(--nospam--at)juno.com> wrote:

my understanding is that 4 bolts are required for erection. It seems that workers lean ladders up against the columns and there have been accidents with the column fallling.

Stan Scholl, P.E.

Laguna Beach, CA



The four bolt rule is indeed for worker safety during the construction process.  

Forget about the ladders...they climb columns directly and having only two bolts makes moment resistance in one direction very small.   The accidents involved rigid body rotation of the column...... with the worker either hitting the ground or the column (& tabs) hitting the worker once he landed.

I would suggest sizing the base plate such that you can achieve your "pinned" column condition but still the 4 bolt condition & have enough moment resistance to handle a "fully loaded" Iron worker load........say ~275 lbs @ 2ft?

Removing the bolts after construction is complete could potentially re-create the hazard during a future demolition, repair or retrofit of the structure.

cheers
Bob


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