7.2systems

AISC 358-22, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications

Last Updated 29 Oct 2026

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Bolted flange plate connections are prequalified for use in special moment frame (SMF) and intermediate moment frame (IMF) systems within the limitations of these provisions.

Bolted Flange Plate Moment Connection

Figure description:

Bolted Flange Plate Moment Connection (Fig. 7.1

Key Components:

Column: Features continuity and doubler plates as required.
Beam: Connected to the column flange using top and bottom flange plates and a web connection.
Flange Plates: Bolted to the beam flanges; may include shims if required.
Single-plate Web Connection: Bolted connection between the beam web and the column.

Dimensional Parameters:

Protected Zone: Defined as $S_h + d$ .
$S_h$ : Distance from the column face to the furthest bolt row on the flange plate.
$S_1$ : Distance from the column face to the first bolt row on the flange plate.
$s$ : Spacing between individual bolt rows.

Fig. 7.1. Bolted flange plate moment connection.

Exception: Bolted flange plate connections in SMF systems with concrete structural slabs are only prequalified if the concrete slab is isolated in accordance with Section 2.3.4.