13.2systems

Double-tee connections are prequalified for use in special moment frame (SMF) and intermediate moment frame (IMF) systems within the limitation of these provisions.

Exception: Double-tee connections in SMF systems with concrete structural slabs are prequalified only if the concrete slab is isolated in accordance with Section 2.3.4.

User Note: Note that connections designed for use in SMF and IMF systems must be designed as fully restrained (FR) connections. It is possible to design double-tee connections that qualify as partially restrained (PR), even when they satisfy all of the strength requirements stipulated within this specification. As a result, care must be taken during design to ensure that the connections resulting from this chapter have not only adequate strength, but that they also have adequate stiffness.

Figure description:

Key Technical Entities and Dimensions: Fig. 13.4

General Context:

• Subject: Structural steel beam dimensions for double-tee connections.
• Purpose: Detailing hole patterns and spacing for bolt placement in SMF/IMF systems.

Top View (Flange Details:

• $b_{fb}$: Width of the beam flange.
• $g_{vb}$: Gauge distance between the two rows of flange bolts.
• $L_{ehb}$: End distance from the beam edge to the first row of bolts.
• $s_{vb}, typ.$: Typical longitudinal spacing between rows of flange bolts.
• $d_{vhb}$: Diameter of the bolt holes in the flange.

Side Elevation View (Web/Overall Details:

• $d_b$: Total depth of the beam.
• $t_{fb}$: Thickness of the beam flange.
• $s_{wb}, typ.$: Typical vertical spacing between bolt holes in the web.
• $d_{whsp}$: Diameter of the bolt holes in the web.

Fig. 13.4. Additional beam dimensions for double-tee connections.

Figure description:

Key Information: T-stub Dimensions for Double-Tee Connections

The image provides technical specifications for a T-stub component used in structural connections, showing top, side, and end views.

Key Dimensions and Parameters:

• $W_T$: Overall width of the T-stub flange.
• $b_{ft}$: Flange width (perpendicular to $W_T$.
• $t_{ft}$: Thickness of the flange.
• $t_{st}$: Thickness of the stem.
• $d_{vht}$: Diameter of bolt holes in the stem.
• $d_{tht}$: Diameter of tension bolt holes in the flange.
• $s_{vb}, \text{typ.}$: Typical vertical spacing between bolt holes in the stem.
• $g_{vb}$: Gage distance between rows of holes in the stem.
• $g_{tb}$: Gage distance between rows of tension holes in the flange.
• $g_{ic}$: Gage distance between inner columns of tension holes in the flange.
• $L_{eht}$: Edge distance from the last stem hole to the end of the plate.

Fig. 13.5. T-stub dimensions for double-tee connections.

Figure description:

This image is a technical diagram illustrating the flange dimensions of a T-stub for double-tee connections.

Key Dimensions and Entities:

• $b_{ft}$: Total width of the T-stub flange.
• $t_{ft}$: Thickness of the T-stub flange.
• $g_{tb}$: Gauge distance between the centerlines of the two bolts.
• $t_{st, eff}$: Effective thickness of the T-stub stem.
• $b$: Distance from the face of the stem to the centerline of the bolt.
• $a$: Distance from the centerline of the bolt to the edge of the flange.
• $b'$: Adjusted distance from the face of the stem to the center of the bolt hole (typically used in prying action calculations.
• $a'$: Adjusted distance from the center of the bolt hole to the edge of the flange.
• Bolts: Two bolts are shown securing the T-stub flange to another component.

Fig. 13.6. T-stub flange dimensions for double-tee connections.