About 20 or so years ago I  got heavily into "Dinosaur Training" (Brooks Kubik).  Thick bar lifts were among the most difficult I have ever done and I know for fact my time for doing them is long over, LOL!
Barbell  curl of 150lbs. 2.5" thick bar.
Close grip bench press of 300lbs with 2.5" bar.  I tried a bottom position with it but could not do it.  I used a pair of saw horses as "spotters".   

  It felt like I was pushing against a small tree, LOL!
This style of training was fun!  But as I said, my time for that has long past.  

  Ooops!  I nearly forgot to add that I weigh around 235 to 240 at that time.  Probably at least 30% bodyfat too...LOL!