Advances in Seismic Design Methodologies - Earthquake Engineering for Structural Design - page 417

Advances in Seismic Design Methodologies 417

- The drift of non-structural elements at various levels of damage can be directly
used in design.
- The structural factor q , used in spectral acceleration response spectrum, it not
needed.

9.4.5 Capacity Response Spectra

The conventional response spectrum is represented by the acceleration versus period
relationship for different damping levels. In the capacity response spectrum format,
the period axis is converted in the displacement axis (Fig. 9.22). The structure period T
is represented by radial lines, instead of being the horizontal axis.
The advantage of this representation is that both strength and displacement
demands are evident in a single graph. The elastic displacement demand and the
structure period may be determined for elastic forces. Considering the inelastic
behavior, the inelastic displacement at the reduced force is obtained in the horizontal
branch of the capacity curve corresponding to the intersection with inelastic reduced
spectra. At the same time, the reduced period due to inelastic deformation may be
determined . Another advantage of this representation is that both earthquake demands
and structure capacity may be compared directly from the same figure .

Figure 9.22 Capacity spectrum (Gioncu and Mazzolani, 2002)