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RE: Levelling plates or shims ?

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When concrete is placed, it does not have a very tight tolerance.  Steel
erection requires much tighter tolerances.  Problem with using what is
called a grout plate are:
When welding the base plate to the column, heat will distort the bottom of
the base plate.
The base plate will not be completely square with the column
The steel frame will probably require leaning the column in order to plumb
the frame depending on the temperature during erection.

The practice that works best is to:
1.	Place the anchor bolts using templates.
2.	Provide about 1 inch of grout space
3.	Set a stack of shims in the center of the base plate that gets the
bottom of base plate to the proper elevation.
4.	Set the column with oversized holes in the base plate
5.	Install the nuts with plate washers to accommodate for the oversized
holes
6.	Plumb the frame
7.	Install nonshrink grout between the concrete footing and the base
plate.

If additional stability during construction is required, drive wedges at the
perimeter of the base plate.  This is the preferred method of most steel
erectors, and is the practice of one of the largest steel erectors in the
US.

Regards,
Harold O. Sprague

> -----Original Message-----
> From:	Acun Uyar [SMTP:acun.uyar(--nospam--at)ihlas.com.tr]
> Sent:	Wednesday, February 27, 2002 3:03 AM
> To:	seaint(--nospam--at)seaint.org
> Subject:	Levelling plates or shims ?
>
> Dear forum members,
>
> I'm designing an industrial building which consists of two-bay portal
> frames. All columns are pin based.
> I suggested to use pipe-sleeved anchor bolts. At this point, I would like
> to
> hear your comments about these two alternatives :
>
> a) Placing 5 mm (3/16") permanent levelling plates and filling underside
> with non-shrink grout
> b) Directly erecting the columns using shim plates, then applying n.s.
> grout
>
> Which of the above seems to be more practical per your field experiences,
> considering column plumb, purlin and bracing installation, etc ?
>
> Best Regards,
>
> Acun Uyar
>

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