Optimal Seismic Performance- Based Design of Reinforced Concrete Buildings - Structural Seismic Design Optimization and Earthquake Engineering - page 226

Figure 8. Initial and final plastic hinge distribution of Case B

No plastic hinge rotation is found to exceed the
specified threshold of plastic rotation, θ U . As
shown in Figure 8(b), the rotations of twenty
plastic hinges of the initial design are found to be
located between the LS-CP state. However, after
the optimization, most of the plastic hinges are
found to be in the B-IO and IO-LS states and only
one hinge is in the LS-CP state, as can be observed
from the optimized framework in Figure 8(c).
Furthermore, the inter-story drifts along the height
of the building are also found to be almost all
fully constrained at the optimum, resulting in a

rather linear deflected profile of the inelastic
design. Such a result further indicates that the
optimization method developed can automati-
cally resize the steel reinforcements of all mem-
bers to attain a uniform ductility demand along
the height of the multi-story building.

4.2 Multi-Objective Optimization
(Case C)

The occurrence probability P r for the severe
earthquake is assumed to be 3.9% according to