Basement – Proper way to secure a basement post to a metal I-beam

If you are butting a rim joist into the beam, you can frame like the first photo with the beam held back 1-1/2" and the first rim joist extending to the end of the post.

Then, in the corner of the second (inner) rim joist and the beam, attach some Simpson A35's. 1 should do, but if you have enough height you could install 2. Each A35 can transfer nearly 600lb of gravity load into the beam. If this truly is a rim joist, then 1,200lb of (2) A35's + the shear on the first rim should be more than enough.

Then use (6+) 3-1/2" quality construction screws (vs cheap deck screws) end screwed through the outer rim into the end of the beam to tie the rim and the beam together.

I would not recommend a Simpson ECC style column cap; these are only needed in extreme (for DIYers) load cases.

Plenty of 1950s/60s gluelam post and beam that are attached with a straight steel heavy strap going from the post to the beam, with bolts through to one on the other side. No need for an angle-bracket, per se. They could also be lag bolted in, but through-bolting with machine bolts and nuts is what I've seen on those buildings. Then again, a stock nailplate truss connector would probably also work (if you need anything - might depend on your earthquake exposure, but then you get back to "what did the engineer specify?")