Design Simpson Strong-Tie Hangers to the NDS

Simpson Strong-Tie is a US manufacturer of structural connectors. In the US, SPEC Toolbox integrates their concealed beam hangers, recognized under ICC-ES ESR-2552, for beam-to-beam and beam-to-column connections. SPEC Toolbox designs the connections to the NDS, using the report’s allowable connection loads.

The integration covers the Simpson concealed beam hangers evaluated in ESR-2552, grouped by type. Each is hidden within the members in the finished connection and is fixed with Simpson Strong-Drive screws.

Concealed beam hangers (inverted-pair)

• CBH, a die-formed steel plate with a welded stud, installed in inverted pairs and fixed with Strong-Drive SDS screws (ESR-2236); for beam-to-beam and beam-to-column connections.
• ACBH (aluminium) and SCBH (steel), concealed beam hangers installed in inverted pairs and fixed with Strong-Drive SDCF screws (ESR-3046); for beam-to-column connections, with the column screws set straight or inclined.

Heavy seated knife-plate hanger

• HSKP, a factory-welded steel back plate, seated bearing plate and knife plate, in three sizes (HSKP5.75×14.5, HSKP5.75×17 and HSKP5.75×19.5), fixed with Strong-Drive SDCF screws (ESR-3046); for beam-to-column connections.

The wider ESR-2552 face-mount hanger range is not part of the US hanger integration.

At a glance, in the US scope the Simpson concealed hangers support:

• Concealed beam-to-beam (CBH) and beam-to-column (CBH, ACBH, SCBH, HSKP) connections.
• Sawn lumber, glued laminated timber and structural composite lumber (LVL), minimum specific gravity 0.50.
• Download, uplift and shear loads, in allowable stress design (ASD).
• Dry service (member moisture content of 19 percent or less, 16 percent for engineered wood).
• Compliance with the City of Los Angeles code and the Florida Building Code, including the High-Velocity Hurricane Zone.

• Fully concealed connections. The CBH, ACBH and SCBH install in inverted pairs hidden between the members, and the HSKP knife plate seats in a slot in the carried beam, so the connection is not visible in the finished structure.
• Aluminium or steel. The concealed beam hanger is offered as the aluminium ACBH or the steel SCBH, and the CBH and HSKP are steel, so the connector material can suit the application.
• High-capacity beam-to-column, including the seated knife plate. The HSKP carries the beam on a steel seat plate engaged by a knife plate, in three depths for large members, and the connections are tabulated for download, uplift and shear.
• Regional code coverage. The hangers were evaluated to the City of Los Angeles code and the 2023 Florida Building Code, including its High-Velocity Hurricane Zone provisions, through the report’s supplements.

The Simpson Strong-Tie concealed hangers are available in the hanger connection calculators, worked in ASD to the NDS:

• beam-to-column (CBH, ACBH, SCBH, HSKP);
• beam-to-beam (CBH).

The allowable load is selected for the carried and supporting members’ assigned specific gravity and the Strong-Drive screw set used, with the connected members checked for bearing and splitting per the NDS.

Design follows the ANSI/AWC NDS under the IBC and IRC. ESR-2552 publishes allowable (ASD) connection loads for the hangers, established by testing to the ICC-ES joist-hanger criteria; the allowable loads already include the load-duration factor and apply to dry service (moisture content 19 percent or less, 16 percent for engineered wood) at sustained temperatures to 100 degrees F. The connections are tabulated for download, uplift and shear, and are fixed with Simpson Strong-Drive screws: SDS screws (evaluated in ESR-2236) for the CBH, and SDCF screws (evaluated in ESR-3046) for the ACBH, SCBH and HSKP. Allowable loads apply to supporting and supported members of minimum specific gravity 0.50 (sawn lumber, glulam or structural composite lumber). The connected members’ own capacity at the connection, including bearing perpendicular to grain and splitting, is checked separately per the NDS; torsion of the CBH, ACBH, SCBH and HSKP, and the reinforced bearing connection of the two taller HSKP models, are outside the report’s scope, as are corrosion exposure and preservative or fire-retardant treated wood. The hangers were also evaluated to the City of Los Angeles code and the 2023 Florida Building Code, Building and Residential, including its High-Velocity Hurricane Zone provisions, through the report’s supplements.