Cutting to the chase, a STR 20 goliath with powerful build comes in at 1200 pounds which is apparently Captain America in the comics.
In detail...
In D&D it says a character can lift 30 x strength score.
Double for each size above medium, so 2x for large, 4x for huge, 8x for gargantuan.
One Marvel comics related page lists natural peak human over-head lift as between 600 and 700 pounds with maximum before being considered super-human as 800 pounds.
It isn't clear what kind of lift either is talking about, but the World records in the snatch and clean and jerk lifting over the head are 496 pounds and 589 pounds respectively - which bumps up to 600 pounds pretty easy if we're being actiony. (The records for the 134 pound competitor weight class in the Olympics were 313 pounds and 379 pounds, so about 64% as much if we want to talk about how much relatively stronger the 30 pound halfling is).
So, a 20 maximum ability score in 5e would be a lifting of 600 pounds which seems about right, so converting strength scores for some human sized folks based on this random web-page
Daredevil 450 pounds = STR 15
Black Panther 800 pounds = STR 26
Captain America 1,200 pounds = STR 40 (or a large with a 20 STR)
Spider-Man - 10 tons = STR 667
Sub-Mariner - 100 tons = STR 6667
More - Hulk, Thor = lots
Converting some D&D monsters the other way doesn't necessarily give anything sensible for huge and gargantuan creatures.
Ogre - Large 19 Str (2x19x30) = 1140 pounds
Hill Giant - Huge 21 Str (4x21x30) = 1.25 tons
Stone or Frost Giant - Huge 23 Str = 1.38 tons
Fire Giant - Huge 25 Str = 1.5 tons
Cloud Giant - Huge 27 Str = 1.62 tons
Storm Giant - Huge 29 Str = 1.74 tons
Gargantuan instead of huge (so like a titan) doubles the giants
Weights of Things
Average Horse 1000 pound
Draft Horse 1800 pounds (0.9 tons)
Toyota Camry = 1.6 tons (Cloud Giant)
Ford F150 = 2.5 tons
Empty School Bus = 5-7.5 tons
Full School Bus = 12-15 tons
Train Locomotive = 100-225 tons
Empty 747 = 200 tons
Max 747 = 440 tons
Aircraft carrier > 100,000 tons
Various crazy uses of human strength are at:
Events - The World’s Strongest Man