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Column-Beam Moment Ratio Check for SMF per AISC 341-16 with ideCAD

Column-Beam Moment Ratio Check for SMF per AISC 341-16 with ideCAD

Owned by Kemalcan Struja (Unlicensed)
Last updated: Sept 07, 2023 by oğuzcan hadim
2 min read

How does ideCAD control the Column-Beam Moment Ratio according to AISC 341-16?

  • Moment ratio is automatically controlled and reported in accordance with AISC 341-16 §E3.

Symbols

ΣM∗pc = sum of the projections of the nominal flexural strengths of the columns above and below the joint
ΣM∗pb = sum of the projections of the expected flexural strengths of the beams at the plastic hinge locations to the column centerline, kip-in.
Ag = gross area of column, in.2 (mm2)
Fyb = specified minimum yield stress of beam, ksi (MPa)
Fyc = specified minimum yield stress of column, ksi (MPa)
Mpr = maximum probable moment at the location of the plastic hinge, as determined in accordance with AISC 358,
Mv = additional moment due to shear amplification from the location of the plastic hinge to the column centerline based on LRFD or ASD load combinations, kip-in. (N-mm)
Pc = the nominal compressive strength
Pr = required axial compressive strength according to Section D1.4a, kips (N)
Zc = plastic section modulus of the column about the axis of bending, in.3 (mm3)
Z = Plastic section modulus about the axis of bending, in.3 (mm3)
αs = LRFD-ASD force level adjustment factor 1.0 for LRFD and 1.5 for ASD

Conditions for Strong-Column and Weak-Beam (SC/WB)

For the highly ductile steel frames or reinforced concrete structural systems with shearwalls and steel frames, the beam-column connections must provide the condition of the Strong-Column and Weak-Beam (SC/WB) approach, depending on the earthquake direction. In beam-to-column connections, the following relationship must be fulfilled:

Where ΣM*pc is the sum of the nominal flexural strength of the columns above and below the joint to the beam centerline with a reduction for the axial force in the column, the determination of ΣM*pc from the Eq (E3-2) is permitted. When the centerlines of beams in opposite directions in the same joint do not coincide, the mid-line between centerlines should be used. For the ΣM*pb, the sum of the expected flexural strengths of the beams at the plastic hinge locations to the column centerline. The determination of ΣMpb* from the Eq (E3-3) is permitted.