On Jun 22, 9:12*am, dpb wrote:
Phil wrote:
On Jun 22, 11:38 am, dpb wrote:

...

Alternate suggestion -- instead of trying to replace the whole thing,
why not ask what it would take in a steel plate bolted alongside the
existing beam to get the span? *(I'd guess 1/2" would do it, but I
didn't try any calc's, that's just gut feel).

...

That's Plan A, or close to it at least. The steel plate has been
speced-out and requires some, as you say, judiciously placed brackets
for the joists. The downside is that the engineer didn't seem to think
that I could get the 16 feet span using this. When we discussed this
plan, we immediatly thought we needed to place the basement columns
under the gound-floor columns to get proper support. You're right
though, I should get him to check if we can get a 16 feet span using
the steel plates solution.

...

I'm having hard time thinking that's not feasible/adequate unless
there's a lot more going on here than a simple two-story. *What's he say
is the limiting criterion, deflection or loading (stress)?

But, if the engineer's convinced the plate alone isn't enough, have a
lower flange welded to it -- either a wide leg angle or T. *In essence a
channel w/o the upper flange that you really don't have need for.

In the extreme, one could even go the "U" but that would surely seem
overkill (again unles....).

W/O actual loadings, drawings, etc., hard to say.

--

dpb-

Great minds think alike........... flitch plates with a piece of
angle iron or channel welded on to serve as a joist seat.

I would suggest using plates both on both sides (symmetry & all).

Rather than bolting through I would recommend to your engineer that
plates have offset hole patterns & use Simpson SDS 2 inch "lags".
They usually can be installed without pre-drilling unless the timber
is very hard / dry.

Make sure hole pattern considers joist locations.

OP-
You didn't give the exact dims of the 3x12's (true 12" or 11.25"?) or
the depth of the joists (2x8's?)
but my rough calc says that plates (1/2" x 12") both sides should
just about do the trick.

Tell your engineer that "through bolting sucks", results in a very
sloppy fit up
and removes too much material from the original member
The Simpson SDS are the way to go.

How about some photos?

cheers
Bob