The laboratory RBS specimens had mostly undergone excessive
out-of-plane deformation before reaching the required inelastic
ductility [8–10]. The out-of-plane deformation is due to the web
local and lateral modes of buckling followed by the flange local
buckling. The severe beam buckling may also result in the
column twisting especially for deep columns [11,12]. Although
the notable out-of-plane deformation is a ductile mode of failure