Peer-to-Peer Standards Exchange

 Modifiers on FR Beam-Column Connection Acceptance Criteria

  • ASCE Standards
  • ASCE41
Matthew Bosch-Willett's profile image
Matthew Bosch-Willett posted 11-15-2023 07:22 PM

ASCE 41-17 Section, paragraph 4, states that the acceptance criteria for FR beam-column connections shall be modified based on four possible factors (continuity plate detailing, panel zone strength, span-to-depth ratio, and beam flange & web compactness).  I am performing a nonlinear analysis of a new steel SMF structure with RBS connections properly designed in accordance with AISC 358-16 Ch. 5 and AISC 341-16 Section E3; columns have been sized to obviate continuity and doubler plates.  I am referencing ASCE 41 Table 9-7.2 for plastic hinge modeling and acceptance criteria.

There are some discrepancies between ASCE 41 and AISC 341.  For example, ASCE 41 Section paragraph 4.1 requires a 0.8 multiplier on the acceptance criteria if the column flange thickness is less than bbf/5.2 and has no continuity plates; by contrast, ASCE 341 Section E3.6f.1(b) does not require continuity plates if the column flange thickness is greater than bbf/6 (Eq. E3-8).  I have some columns whose flange thicknesses are greater than bbf/6 but less than bbf/5.2.  I would expect that these modifiers on the acceptance criteria are applicable primarily to historic moment connections and are thus not appropriate for properly detailed modern SMF connections.  Is my interpretation correct?

Ronald Hamburger's profile image
Ronald Hamburger


As a member of the ASCE 7, 41 and AISC Specs Committee, I would agree with your reflection that these modifiers are not applicable to moder, prequalified connections.  However, you may wish to review the criteria in the newly issued AISC 342 Specification available for free download from AISC (for professional members).  This Specification "Seismic Provisions for Evaluation and Retrofit of Steel Buildings" substantially updates the AISC 41 criteria and presents AISC's recommendations for nonlinear analysis of steel structures.