Structural Engineer for Shop?

[Phil Thien]

BTW, one of the things you can try if that I-beam is only supported at the ends is, you can temporarily add a couple of 4x4 or doubled-up 2x4 posts to split-up the span and then go walk (jump) upstairs and see if the bounce has improved.

You can also run a chalk line from end to end of the I-beam, pull it tight, and use that to check for deflection in the I-beam. Have your wife/kids go walk around upstairs and watch for any changes between the string and the beam.

I-beams do deflect. In fact, we've probably all, at one time or another, been in a shopping mall or commercial building where we could feel the floor bounce. Locally, our Mayfair mall 2nd floor has quite a bit of bounce in some areas.

[David Gutierrez]

Chen at 2x10 @ 16oc with 12' span will support about 80 pounds per square foot total load, assuming douglas fir larch #2. If the saw has a foot print of 30" x 30" or 6.25f of floor area and weighs 600 lbs then the live load is 96 pounds per square foot. you should also allow 10 PSF for dead load, the weight of the floor itself. the live load available is 70 PSF. You will be over the live load capacity by 37% that is too much. You should get a architect or engineer to take a look at this for you.
the other thing to consider is the floor itself 3/4 inch plywood subfloor may need some help depending on the finish floor.

[Chen-Tin Tsai]

I think that with the load being right at the limit, plus my future expansion plans (hard ducted DC, larger hand tool bench, project lumber storage, etc), I'll be bringing in a structural engineer to give me an evaluation and discuss options.

[David Gutierrez]

Chen
that is the best thing to do. An architect would also be able to help you with this. Who ever does it should check the joists, beam and subfloor.

[Brett Bobo]

Please, let's not confuse engineers with architects and vice versa as we are not one and the same.

[Mel Fulks]

Brett is right ,but that wasn't always so. Architects used to have to do their own engineering,the word means "chief builder" . Long history of architects staying on site and directing work. Benjamin Latrobe designed the masonry dome of the Philadelphia bank and personally showed the masons ,who had never built one ,exactly how he wanted it done. Top of it was 160 feet plus over floor. Separation of the two professions was a great thing for lawyers as around here they are always suing each other .