Symbols
Ry = Ratio of the expected yield stress to the specified minimum yield stress, Fy
Rt = Ratio of the expected tensile strength to the specified minimum tensile strength, Fu
...
AISC 341-16 Provision employs uses a methodology for special moment frames, special concentrically braced frames, and eccentrically braced frames seismic systems that can be defined as “capacity design.” In capacity desigCapacity design philosophy is aimed certain members intended to undergo inelastic deformations to be able to absorb energy efficiently. So, the required strength of members that are refered to behave essentially elastically is defined by forces corresponding to the capacity (expected strength) of certain members intended to undergo inelastic deformations.
...
Similarly, rupture limit states within the designated yielding element are affected by increased material strength.
...