Usage patterns
柱を立てるto put up a pillar/post
The carpenter put up the pillars for the new house.
〈事〉の柱となるto become the mainstay/pillar of something
He is a person who serves as the mainstay of this company.
柱にぶつかるto bump into a pillar/post
It was dark, so I bumped into a pillar.
〈物〉を柱にするto make something the central pillar (of a plan, policy, etc.)
They are making this policy the central pillar of economic recovery.
Expressions
杖とも柱とも頼むto lean entirely on someone; to count on someone as one's sole support