5.3.1 Beam Limitations
Beams shall satisfy the following limitations:
- (1) Beams shall be rolled wide-flange or built-up I-shaped members conforming to the requirements of Section 2.3.
- (2) Beam depth shall be limited to a maximum of W44 (W1100) for rolled shapes. Depth of built-up sections shall not exceed the depth permitted for rolled wide-flange shapes.
- (3) Beam weight shall be limited to a maximum of 408 lb/ft (610 kg/m).
- (4) Beam flange thickness shall be limited to a maximum of 2¹/₈ in. (53 mm).
- (5) The clear span-to-depth ratio of the beam shall be limited as follows:
- (a) For SMF systems, 7 or greater.
(b) For IMF systems, 5 or greater.
- (6) Width-to-thickness ratios for the flanges and web of the beam shall conform to the requirements of the AISC Seismic Provisions.
When determining the width-to-thickness ratio of the flange, the value of shall not be taken as less than the flange width at the ends of the center twothirds of the reduced section provided that gravity loads do not shift the location of the plastic hinge a significant distance from the center of the reduced beam section.
- (7) Lateral bracing of beams shall be provided in conformance with the AISCSismic Provisions. Supplemental lateral bracing shall be provided near the reduced section in conformance with the AISCSismic Provisions for lateral bracing provided adjacent to the plastic hinges.
When supplemental lateral bracing is provided, its attachment to the beam shall be located no greater than d/2 beyond the end of the reduced beam section farthest from the face of the column, where d is the depth of the beam. No attachment of lateral bracing shall be made to the beam in the protected zone.
Exception: For both systems, where the beam supports a concrete structural slab that is connected between the protected zones with welded shear connectors spaced a maximum of 12 in. (300 mm) on center and where the beam depth, beam weight, and column depth are not larger than W36 (W920), 302 lb/ft (450 kg/m), and W36 (W920), respectively, supplemental top and bottom flange bracing at the reduced section is not required.
- (8) The protected zone shall consist of the portion of beam between the face of the column and the end of the RBS cut farthest from the face of the column.
5.3.2 Column Limitations
Columns shall satisfy the following limitations:
- (1) Columns shall be any of the rolled wide-flange shapes or built-up shapes permitted in Section 2.3.
- (2) The beam shall be connected to the flange of the column.
- (3) Rolled shape column depth shall be limited to W40 (W1000) maximum. The depth of built-up wide-flange columns shall not exceed that for rolled shapes. Flanged cruciform columns shall not have a width or depth greater than the depth allowed for rolled shapes. Built-up box-columns shall not have a width or depth exceeding 24 in. (600 mm). Boxed wide-flange columns shall not have a width or depth exceeding 24 in. (600 mm) if participating in orthogonal moment frames.
- (4) There is no limit on the weight per foot of columns.
- (5) There are no additional requirements for flange thickness.
- (6) Width-to-thickness ratios for the flanges and web of columns shall conform to the requirements of the AISC Seismic Provisions.
- (7) Lateral bracing of columns shall conform to the requirements of the AISC Seismic Provisions.