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- To: seaint(--nospam--at)seaint.org
- Subject: Bolted Connection To Existing Old Steel
- From: "Ddumba Nathan" <ddumba(--nospam--at)engineer.com>
- Date: Thu, 16 Mar 2006 06:00:57 -0500
Firstly, in regards to the phobia, would the following do something about it?
1. finding out how the chemical and subsequently the mechanical properties of steel change with time,
2. getting a sample of that existing beam and testing for its mechanical/chemical properties
3. then working out the maximum shear load an effective welded section can take on (safety ensured) the available loading.
Otherwise the possibility being considered is not bad at all. Are you drilling right through the beam encased in concrete? if not then I would also think of doing your suggestion together with that 'easiest solution' mentioned earlier to ensure rigidity and extra safety since we are also dealing with vibratory/dynamic loads from the elevator once functioning. But ofcourse all this depends on how much the combined (the stud-like system and the welding) can take on.
Ddumba Nathan, SEng.
This is a multi-part message in MIME format.
As some of you know, I am working on an important old heritage =
building. A problem detail which I would like to discuss with you has =
come up. The details follow.
An abandoned elevator shaft needs to be enlarged and returned to =
service. This will require removing an existing steel beam and =
replacing it with a new beam 1.5 to 2 feet away. The problem is that =
one end of the new beam must connect to an exterior beam which is =
encased in concrete as well as bricked over on the outside.
The obvious solution is to connect the flange of a T (perhaps =
fabricated from plate) to the existing steel and weld the web of the new =
beam to the stem of this T. The load in the order of five thousand =
pounds in shear (no tension). The devil is in the detail.
The easiest solution would be to weld the T to the existing web =
but I have a phobia against welding to very old steel.
Using a standard bolted connection would work but it would =
require six stories of scaffolding, concrete repair, brick repair lane =
blockage, construction permitting, and a lot of inconvenience. All very =
expensive and somewhat time consuming.
An other possibility is being considered; and on this I would =
like your thoughts. Do you think we could drill and tap the web of the =
existing beam from the inside only and use bolts like studs to make the =
connection? The web is probably between 0.25 and 0.375 inches thick. I =
have no problem installing four vertical rows of 3 or 4 bolts each =
(machine bolts, probably; A325 bolts could never be tensioned in the =
relatively thin, low strength web). I could even partially or fully =
weld the heads of the stud bolts to the flange of the new (fabricated) T =
to create fully fixed projecting dowels if desired.
Thank you for any comments you might choose to make.
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