Moment Connection Design or Rigid Connection design is made automatically according to the Design, Calculation and Construction Principles of Steel Structures (ÇYTHYEDY) (GKT and YDKT) and AISC 360-16 (ASD and LRFD) regulations. Bolt, weld and plate controls, geometry controls and strength controls are done automatically in accordance with the steel connection type.

Moment connection types are listed below.

Design Criteria for Moment Connections

  • Moment connections are classified as rigid and full/partial strength connections.

  • For rigid connections, end plate and welded connections are classified according to the rotational rigidity which is defined according to the earthquake regulations depending on the ductility level.

Guideline for End Plate Connections

  • The strength of the end plate connection is determined by the assumption that the tensile force of the bolts on a part of the plate and compressive forces of the bolts on the other part of the plate is controlled by the bearing limit state.

  • If there is no axial load on the connection, the total tensile and compressive forces are equal and opposite in both parts which create force pair.

  • To simplify the calculations, it is assumed that the center of rotation is in the center of the compression part.

Guideline for Splice Connection of Columns/Beams

  • In order to be suitable for the design under reversible forces such as earthquake forces, symmetrical and equal number of bolts are used on both flanges and webs. ideCAD does not allow asymmetrical connection during modelling.

  • It is assumed that the flanges carry the moment and web carry the shear force, while the axial force is equally shared between both flanges.

  • The gap is left in between the beam splices, while for the column splices it may or may not be left.

Guideline for Moment Connections with TBDY 2018

  • Depending on the ductility level, the connections need to provide a relative angle of translation of at least 0.04 or 0.02 radians according to the TBDY 2018 9B.1. These connections are End Plate and Flange Plate connections that are designed in ideCAD Structural Steel.

  • If the design of the connections is preferred to be computed with TBDY 2018, the YDKT method is mandatory in accordance with the earthquake regulations.

  • The required bending moment strength Muc and the required shear strength Vuc on the column face of the connections is calculated over the plastic hinges at the end of the beam. The formulas in the figure below are used.

  • The Vuc used in the dimensioning of the connection is determined according to the equation in the figure above by summing the shear force determined on the basis of the yielding limit state with the shear force calculated from the combination of 1.2G + 0.5Q + 0.2S on the plastic hinge at the end of the beam.

  • Plastic hinge length is specified separately for each connection in TBDY 2018 and automatic computation is made in accordance with these rules. Details will be given in each connection.

  • The shear strength required for the panel zone is calculated by using the column shear force generated by the possible plastic moments of the beams connecting to the column.


Cpr: This coefficient takes into account the strain-hardening which is used to compute maximum possible bending moment strength

Fu: Characteristic tensile strength of steel

Fy: Characteristic yield stress of steel

lh: The distance of between plastic hinge point at the beam end to the column face

ln: Beam span between plastic hinge points at the beam ends

Mpr: Possible bending moment strength

Mpri: Possible bending moment strength at the left end i of the beam

Mprj: Possible bending moment strength at the right end j of the beam

Muc: Required bending moment strength of the connection at the face of the column

Ry: The ratio of possible yield stress to the characteristic yield stress

Vd: Beam shear force computed from vertical loads at the plastic hinge point of the beam

Vuc: Required shear strength of the connection at the face of the column