Any form of rolled iron having a cross-section resembling the letter I. (noun)
The Century Dictionary (Public Domain)
Use "i-beam" in a sentence
"As you can imagine, there's so much debris, concrete, big pieces of metal, those big i-beam structures that were the trusses for the bridge, and a lot of reinforcing rod."
"This is structural steel, a foot by about six inch i-beam construction building that is just in a shambles here that was effaced with brick."
"Now it is being developed by i-beam design for use as inexpensive and efficient low-cost housing not only for people displaced by natural disasters but also as a solution for affordable pre-fab housing."