ArcelorMittal

Tel: +352621205109
Website: https://sections.arcelormittal.com/

Contact ArcelorMittal

Reduced Beam Sections (RBS)

ArcelorMittal – Luxembourg

• Long-span, high-capacity members are essential for tall buildings, arenas, and terminals.
  ArcelorMittal’s latest profiles support such applications with jumbo steel sections.
• In seismic zones, welded connections must be designed per WPS to ensure rotational capacity for inter-story drift.
• Reduced Beam Sections (RBS) help limit flexural demand at the beam-column interface.
• Introduced after the 1994 Northridge Earthquake, RBS shifts the plastic hinge away from the column by trimming flanges, separating stress concentration from plastic strain.

---

Characteristics

Whilst removing material may seem paradoxical and potentially uneconomical and indeed potentially uneconomical, in fact, beam sections are normally sized to meet deformation requirements under gravity and earthquake loadings, often providing more resistance than is needed (‘overstrength’).

The only effect of adopting RBS is therefore to consume part of this excess. It also :

• reduces very slightly the stiffness of the structure (between 4% and 9%), because sections are only reduced over very short lengths of the beams
• normally does not require any change in the section sizes of the structural elements in order to compensate this minor stiffness reduction
• reduces the ultimate strength of the structure, but not significantly because, as noted above, there is normally a high excess of resistance anyway
• allows column section sizes to be reduced, assuming they have been sized by the ‘strong columns-weak beams’ capacity design condition
• allows the dimensions of any stiffeners needed in the columns for the transmission of bending
  moments and shear in the connection zone to be reduced, which can result in a significant
  reduction in fabrication costs

---

Categories

Prevention Solution, Earthquake