Beam Design- how would this work

[skiwest]

I'm in the process of building a 21 by 32 foot cabin on piers.  For the piers I went all out with footings ended up 100% more than code using high design factors.  28x 28 square foots like bigfoots but square.  12" piers with 60" below grade reinforced with 1/2 " rebar x 3. Piiers are in 3 rows , 9' spacing across, 10' length wise.

Above grade piers are 36" to top of concrete from grade.  In the center of each pier I've got a 1" or 3/4" (1" at corners) threaded rod.  18" above concrete.

WHat Ihad originally planned was the beam sitting on a steel plate with the height of the plate adjustable by nuts on the threaded rod.  So I would have to drill through the beam and set the beam down over the rod.

Now I'm thinking that the beam 4 - 2X12s could be two parts both 2 - 2x12s with spacers in between.  Difficult to describe.  But would allow not to drill into beam but in to a short section of 2x12. Then attach both sub beams to spacers.  Would put 2x12 where ever there is a splice and 2x4s other places.

Any comments

[PEG688]

I'd buy it if you thru bolt the whole works together with 1/2" bolts with nuts and washers , about 20" OC staggered one up , one down . About 2" from the edges of the 2 bys .

------------------------------------------------------------
 2"                                    
  X                                    X

     (   20"        )                     (     20"   )

                    X
                    2"
 -------------------------------------------------------------  

 BTW I'm not a structural engineer and you should run it by your building dept. if one is involved.