Cov hlau i beam, txawm tias yog ib txwm lossis sib dua, muaj qhov loj me ntawm qhov seem siab thiab nqaim, yog li lub sijhawm ntawm inertia ntawm ob lub axis tseem ceeb ntawm qhov seem seem sib txawv heev, yog li nws tsuas yog siv tau ncaj qha rau cov tswv cuab uas khoov rau hauv lub dav hlau ntawm nws lub phaj web lossis ua los ntawm cov tswv cuab latticed. Nws tsis haum rau cov tswv cuab axial compression lossis cov tswv cuab uas khoov rau hauv lub dav hlau perpendicular rau lub web, uas txwv lawv daim ntawv thov.
Cov hlau I beam feem ntau muab faib ua cov hlau ib txwm I beam, cov hlau sib zog I beam thiab cov hlau flange dav I beam. Cov hlau I beam nrog cov flange dav, cov flange nruab nrab thiab cov flange nqaim raug muab faib raws li qhov siab ntawm cov flanges rau webs. Cov lus qhia ntawm ob qho qub yog 10-60, uas yog, qhov siab sib xws yog 10 cm-60 cm. Ntawm tib qhov siab, cov hlau sib zog I beam muaj flange nqaim, web nyias thiab lub teeb yuag. Cov hlau I beam nrog flange dav, tseem hu ua hlau H beam, yog tus yam ntxwv los ntawm cov ceg sib luag thiab tsis muaj kev sib hloov hauv cov ceg. Nws yog rau cov hlau seem kev lag luam thiab dov rau ntawm plaub-siab universal dov zeb, yog li nws tseem hu ua "universal steel I beam".