9.3. MOMENT RESISTING STEEL FRAMES WITH HIGH DUCTILITY LEVEL

Steel frames with highly ductile members that transfer loads and moments are expected to provide significant inelastic deformation capacity through flexural yielding of the beams and limited amount of non-linear deformation of column panel zones under the earthquake actions. Rules for the dimensioning of the steel frames with highly ductile members are given below:

9.3.1. General Conditions

9.3.1.1 - The width-to-thickness ratios of elements should not exceed the limiting width-to-thickness ratios, λhd, from Table 9.3, for members designed as highly ductile members.

9.3.1.2 - Both flanges of beams shall be supported against lateral and torsional displacements based on the conditions specified in 9.2.8 for members with high ductility level.

9.3.1.3 - Internal forces to be used in the design of beams are axial forces, shear forces and bending moments, that are evaluated by considering the load combinations that create most unfavourable conditions.

(a) Shear force, axial force and bending moments to be obtained by taking into account the load combinations including the earthquake effect given in 9.2.5.

(b)  Axial tensile and compressive forces to be obtained in accordance with 9.2.6, regardless of bending moments. However, if there are horizontal forces acting between the column ends, the bending moments that they will create will also be taken into account.

9.3.1.4 - Highly ductile beams of moment-resisting steel frames shall be dimensioned under the most unfavourable internal forces obtained according to 9.2.5.