1
general::
Phrase(s): buckle under something
to collapse under or from the weight of something. • The bridge buckled under the weight of the truck and collapsed. • The table finally buckled under.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Give way, collapse owing to stress, as in One more heavy snowfall and the roof may buckle under, or She buckled under the strain of two jobs. [Late 1500s]
American Heritage Idioms