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Re: ??Reinforcing DL's in compression??

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I guess its obvious, but don't forget to check the shears associated
with the increased moment capacity. You usually want to force plastic
moment failure before a shear failure.


-----Original Message-----
From: Harold Sprague <harold.sprague(--nospam--at)>
To: 'seaint(--nospam--at)' <seaint(--nospam--at)>
Date: 08 October, 1998 4:05 PM
Subject: RE: ??Reinforcing DL's in compression??

>The master for this type of problem is Ray Tide at Wiss, Janney &
>He has written several articles on reinforcing steel elements under
load.  I
>have reinforced steel members also by welding reinforcing elements
>load.  You need to evaluate your existing load, the final load on the
>element, and the effect of welding.
>I generally like to develop a welding procedure to minimize heat
input.  The
>element will deform due to the welding process.  I don't think that I
>enough about your problem to advise you on a final solution.
>Additional questions are:
>Is it a case of adding section to increase area to drop the stresses?
>Are you adding section to increase the radius of gyration
>Is the end connection adequate?
>1. AISC Engineering Journal, 4th quarter, Reinforcing Steel Members
>the Effects of Welding, by R. H. R. Tide.
>2. Proceedings, AISC National Engineering Conference, New Orleans,
>April 1987, Basic Considerations When Reinforcing Existing Steel
>R. H. R. Tide.
>Harold Sprague, P.E.
>The Neenan Company
>-----Original Message-----
>From: Khosrownia, Ghassem NWS
>Sent: Thursday, October 08, 1998 9:05 AM
>To: 'SEAOC List Server'
>Subject: ??Reinforcing DL's in compression??
>I have a consultant who proposes to reinforce an underdesigned DL
>diagonal by welding additional plate to their projecting legs. The
area of
>steel required is based on the required additional capacity needed.
>welding design, the consultant is using the full axial load in the
>section in order to determine the length of weld. While this may
>conservative results, I feel like the approach is not logical. I
think the
>plate should be attached to the hosting DL's in such a manner to be
>in compression and to be able to contribute the lacking strength. If
>plate should provide 10 kips of additional capacity, then its weld
>should be determined based on stability of the plate in compression,
>allowable compressive stresses associated to that.
>What do you think?
>I appreciate all comments.