beam; joist
「梁」 has other readings with different meanings.
古い家の梁は見事な木造だ。
The beams of the old house are magnificent woodwork.
古い家の梁が腐って危険です。
The beams of the old house are rotten and dangerous.
天井の梁が古くなって、修理が必要です。
The ceiling beam has become old and needs repair.