I’m currently in the underground section of an LMOE shelter, and you know all those crates? They say “smashable” but I’ve been wailing on them for 10 minutes now with 9 strength and can’t get the 3 in the back. Popping them open doesn’t work.
bashing them with an item that has a high bash damage helps. Try opening them like you would a door. Apart from that it is unclear how much str you need. Could be impossible. Sorry about that.
Use a crowbar.
I’m pretty sure I’ve broken open crates with 10 Str and a decent bashing weapon. And I know for sure that I’ve smashed crates under somecircumstances.
Use a crowbar, and yeah, I can confirm that they’re smashable (at least if they’re the same as the ones in FEMA camps).
I can break them with a nail board or so in under 100 hits. 9 str
Personally, I disassemble the crates, in the same way that I might any piece of furniture.
disassemble works faster. but even if you have 12 str, bashing a window with a plastic wrapper takes forever. use a solid item (hammer, crowbar, rock even) and if you already are, disassemble.
I just found out that you can take everything out of a sealed crate using the advanced inventory management. 
This has been fixed now.