David Blockley, a professor emeritus at the University of Bristol in the United Kingdom has an interesting web page about bridges. The page is geared towards educational outreach for younger students. Professor Blockley compares the process of understanding how a bridge works to reading a book. The section of his site on "How to Read a Bridge" shares some ideas on the different on the different forms and components of a bridge, not just structurally but also how a bridge satisfies other functions.
Professor Blockley writes:
"To read a bridge you need to know that there are basically 4 types of structural forms of which one or more occur in all bridges.
"You can remember them because they are BATS
B is for beams
A is for arches
T is for trusses and
S is for suspension or hanging structures."