The advantage of Special Concentrically Braced Frame (SCBF) in the
seismic steel design is high R factor. Currently, the usage of Chevron bracing is
much avoided because it requires the beam to be designed due to unbalanced
forces which exist because of the redistribution forces in the bracing that
withstand the compression force is buckle. The alternative beside Chevron bracing
is two-story X-bracing that can withstand the unbalance forces on the beam so that
the beam cross section becomes smaller. But research results in three SCBF (3, 9
and 18 stories) by Richards (2009) using static pushover analysis and non-linear
dynamic analysis with 10 earthquake records show that the normalized column
demands which is the ratio between the maximum axial force (Pu) to axial force
elastic lateral load equivalent (Pe) reached Pu / Pe = 4.2 for the first and second
story columns on 3 stories of SCBF, 2.2 ≤ Pu / Pe ≤ 4.8 for all columns on 9
stories of SCBF and 1.8 ≤ Pu / Pe ≤ 5.0 for the fifth story column upward on 18
stories of SCBF. The results of this study show the seismic column demands (Pu)
in CBF with low and moderate levels could exceed ΩoPe = 2 Pe for