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Re: structural welding

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Jason,

        Following are some comments which may be helpful.

Problem 1.

        I don't have a problem doing it either way.  If you decide to weld you
must have the material tested for weldability and you must have a professional
engineer qualified to specify and assume responsibility for the weld
procedures.  I'm not belittling your own abilities; in Canada a fabricator can
not legally do structural welding unless they are approved by Canadian Welding
Bureau (CWB); and CWB approval requires that they have on staff or on retainer
just such an engineer.  I personally am not CWB approved, nor are most other
consultants.

        As an alternative you might consider bolting two channels back-to-back
with the existing beam web in between.  A three or four feet overlap with the
existing beam might give you all you need for the moment splice.

Problem 2.

        You could do it the architect's way; you could use channel(s) on the
side(s) as per my suggestion above; or use the architects T idea but make the T
a half inch (give or take) deeper or shallower than the existing and have a
single shear lap splice with the existing bottom flange.

        You might want to jack both these beams before making the final
connection to eliminate any residual stresses any "shored vs. unshored"
composite effects.

        Regarding your final question, I don't think there is any reliable
"data" on the existing steel;  mill certificates are one of the first things
that are thrown away even today.  You will have to test the material.

        Hope this is of some use.

Regards,

H. Daryl Richardson

Jason Kilgore wrote:

> I'm working on a renovation of an existing structure.  The building was
> originally built about 1908.  It has one-and two-way CIP concrete slab
> floors over steel beams and columns.  It appears as if there was the
> intention of adding more floors to the building at t later date (this
> happened to several of the buildings of similar construction in the area).
> No plans of the existing structure are available.
>
> At some time between 1908 and now, someone added a three-stop elevator
> between the basement and the second floor.
>
> Problem 1: This elevator happened to fall centered on a grid, so they simply
> cut the beam and supported the free end on the shaft wall.  The architect
> wants to remove the wall, infill the floor opening, and make it someone's
> bedroom.  There isn't enough room to add another full-length beam under the
> existing one.
>
> Solution: The architect proposed "replacing" the missing beam with a simple
> shear connection to the column and a full-pen weld to the end of the
> existing beam.  I don't like this, so I'm thinking about taking some
> detailed measurements and designing a bolted moment connection at the joint.
> Any comments?
>
> Problem 2: There wasn't quite enough headroom above the second floor, so
> they took a torch and cut off the bottom half of the steel beam!!!
>
> Solution:  Since the third floor hasn't fallen in yet, the architect
> proposed replacing the "missing" T portion of the beam with a full-pen weld.
> Does anyone have any other idea?  I'm stumped.
>
> As for the welding idea, where can I get weldability data from that time
> period?
>
> ----
> Jason W. Kilgore, P.E.
> Leigh & O'Kane, L.L.C.
> jkilgore(--nospam--at)leok.com
> (816) 444-3144
>
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