RBS connections are prequalified for use in special moment frame (SMF) and intermediate moment frame (IMF) systems within the limits of these provisions. The RBS connection is exempt from the requirements of Section 2.3.4.
Figure description:
Technical Diagram: Reduced Beam Section (RBS Connection
- Key Entity: A steel beam-to-column connection featuring intentional narrowing of beam flanges to facilitate plastic hinging away from the column face.
- Geometric Parameters:
- a: Distance from the column face to the start of the flange reduction.
- b: Length of the reduced beam section.
- c: Depth of the circular cut into the flange.
- R (Radius of cut: Calculated using the formula .
- Designated Zones:
- Reduced Beam Section: The specific area where flange width is narrowed.
- Protected Zone: The region extending from the column face to the end of the reduced beam section where strict construction limitations apply.
- Structural Components:
- H-shaped column and beam sections.
- Bolted shear tab connection at the beam web.
- Welded flange-to-column face connections.
Fig. 5.1. Reduced beam section connection.