I-beams are used as horizontal roof beams in buildings with significant spans and as floor beams subjected to high loads. I-section is typical and most rational for prestressed beams.
The fire resistance of such I-beams equals to 60 minutes. To run various kinds of service lines, this type of beams can be provided with holes. IB are used to cover spans of up to 24 m; IB12 are used to cover spans of 12 m.