Simulator · Structural steel
Reduced beam section (RBS) moment connection
The RBS connection is designed so that the plastic hinge forms within the reduced section and not at the column face. The assumption is checked with two methods that share no assumptions: the AISC 358 equations, which fix the hinge location and its moment, and a finite element model that takes the beam to increasing rotation without imposing the location of yielding.
FEM 758 · AISC 358 725 kN·m · 4.5 % difference
AISC 358 · live calculation
Other sections with the code equations
The finite element model is solved for a W21×62. For other sections, this calculator applies AISC 358 chapter 5: reduced plastic modulus, probable moment, moment at the column face and the Mf ≤ φd·Mpe check, with the cut geometry and the elastic stress along the flange.
Input Parameters
d = 526 · bf = 165 · tf = 11.4 · tw = 8.89 mm · Zx = 1,563×10³ mm³
Cut geometry
a = 103 · b = 395 · c = 33.0 · R = 606 mm
Results (AISC 358-16, ch. 5)
σ/Fy in the top flange (plan)
Yielding at the reduced sectionModel scope: A992 steel, Fy = 345 MPa, Fu = 450 MPa, Ry = 1.1. Circular cut with a = 0.625·bf and b = 0.75·d; distance between hinges Lh = 6.0 m, no gravity load on the span. The stress field is elastic, σ = M/S, with M linear from the column face and S reduced by the cut; values σ/Fy ≥ 1 mean yielding.
Use of the simulator
Demonstration material, not for design. The calculation notebook and the application of the method to a project are reviewed in a technical meeting.
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