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Re: Bolted Connection To Existing Old Steel

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        I expect the T would have slipped into bearing before the bolts are tightened.  There should be no gap for the bolts to span, hence little or no bending in the bolts themselves (I think).  Of course, due to construction tolerances, only some of the bolts would be in bearing; some might have nominal bending if the plate slipped further than initial bearing; but this is a factor in any bolted detail.  Even so I would seem to have room for 12 or even 16 bolts if needed (or desired) so bolt stress shouldn't become an issue.
        Thanks for your reply.
H. Daryl Richardson
----- Original Message -----
Sent: Tuesday, March 14, 2006 6:26 AM
Subject: Re: Bolted Connection To Existing Old Steel


If I understood your idea correctly, the bolt will be in bending and shear.  Bolt does not have much of flexural capacity.


Daryl Richardson <h.d.richardson(--nospam--at)> wrote:
Fellow engineers,
        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.
H. Daryl Richardson

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