Prequalified Moment Connection Calculator, AISC 358-22

What it checks

The module designs prequalified moment connections for steel frames, supporting RBS, BFP, WUF-W, ConXL, and SidePlate connection types. It applies AISC 358-22 provisions to evaluate the structural adequacy of the connection under specified seismic system types, including SMF, IMF, and OMF. The design method relies on strength-based checks to verify that the connection can deliver the probable moment and shear demands. The sequence of checks begins with verifying the highly-ductile flange limits for the beam section, followed by the calculation of the reduced plastic modulus for RBS connections. The module then evaluates the expected plastic moment and shear at the hinge, comparing these values against the connection's capacity to ensure the panel zone and continuity elements meet code requirements.

Inputs

Connection Definition - connection type (RBS, BFP, WUF-W, ConXL, SidePlate) and system type (SMF, IMF, OMF).
Beam Geometry - clear beam span (ft), plastic section modulus (in3), and Ry factor (1.1 for A992).
Material Properties - modulus of elasticity (ksi), typically 29000 for steel.
Load Demands - moment demand at column face (kip-ft) and gravity shear at hinge (kips).
RBS Dimensions - cut distance from column face (in), cut length (in), and flange cut depth (in); zero values trigger automatic sizing based on beam width and depth.
Weld Details - CJP weld size (in).
Probable Capacity - expected plastic moment at hinge (kip-ft) and expected shear at hinge (kips).
RBS Factors - reduced plastic modulus at RBS cut (in3) and Cpr strain-hardening factor; both set to zero for non-RBS connections.

What it reports

Highly Ductile Check - verifies the flange width-to-thickness ratio against the limit for highly ductile sections, such as the W36x150 failure case where the ratio exceeds the allowable value.
Reduced Plastic Modulus - reports the ZRBS value for RBS connections, comparing the cut section properties against the original beam modulus.
Strain Hardening Factor - provides the Cpr value used to adjust the expected plastic moment for RBS connections.
Expected Plastic Moment - calculates M*pb at the hinge and verifies it against hand calculations for specific sections like W24x84.
Expected Shear - calculates V*pb at the hinge, including the contribution of gravity shear, and verifies it against hand calculations for sections like W21x62.
Connection Type Verdict - confirms the selected connection type (RBS, BFP, WUF-W, ConXL, or SidePlate) is compatible with the specified system type.

Code references

The engine cites AISC 358-22 for prequalified moment connections, specifically referencing Section 5 for RBS, Section 6 for BFP, Section 8 for WUF-W, Section 9 for SidePlate, and Section 10 for ConXL. It also references AISC 16th Edition Table 1-1 for section properties and the highly-ductile check limits defined in the code.

Limits

The module assumes specific material properties, such as Ry = 1.1 for A992 steel and E = 29000 ksi. It does not calculate RBS dimensions if the input is zero, instead relying on automatic sizing rules based on beam width and depth. The module does not cover connection types outside the specified list of RBS, BFP, WUF-W, ConXL, and SidePlate. Results are engineering aids; the engineer of record is responsible for the design.

This module ships in the desktop app

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