i have a 24'x24' garage with a 6"x6" wood column right in the middle supporting a beam that crosses the garage. the beam is 3 2x12's laminated together (supports the upstairs wall). the wood column is cracking and is twisted. actually it was twisted when it went in as the little concrete pad (part of the slab pour) is twisted to match the post. house was built in 1982. i'd like to replace the 6" wood column with a 4" diameter, 1/4" wall round steel column. it will have a 12x12 1/4" plate welded on the bottom to bolt it to the slab and u-shaped bracket welded to the top to hold the beam with a couple bolts thru that. can i do this? can a 4" steel column replace a 6" wood column? a friend thinks it's overkill, but i like overkill. what size bolts should i use to bolt it to the concrete? 1/2? 3/4? thanks.