girder vs hammer beam

girder

noun
  • A beam of steel, wood, or reinforced concrete, used as a main horizontal support in a building or structure. 

  • One who girds; a satirist. 

hammer beam

noun
  • A member of a kind of roof truss (a hammer-beam truss), so framed as not to have a tiebeam at the top of the wall. Each principal has two hammer beams, which occupy the situation, and to some extent serve the purpose, of a tiebeam. 

How often have the words girder and hammer beam occurred in a corpus of books? (source: Google Ngram Viewer )