Challenges for the Next Generation of Seismic Codes - Earthquake Engineering for Structural Design - page 521

Figure 10.40 Classification of analysis methods (Gioncu and Mazzolani, 2002)
• Ultimate limit state (survivability), under severe earthquake, where all
non-structural elements are completely damaged and a global
mechanism is formed. The analysis follows kinematics procedures. The
basic verification considers the available ductility, which is expressed
by the rotation capacity of plastic hinges.
The performance-based design itself will not provide an improved or more
predictable structural performance. The design only gives a set of drawings and
instructions for the builder. The quality of the built product will depend on the
development of methodologies incorporating new achievements in demand and
response capacity of the structures (Krawinkler, 1999). As has been shown in this
chapter, the demand cannot ignore the earthquake type and the response capacity
directly depends on this demand.
10.8.3 Influence of Earthquake Type
Despite using very advanced design methodologies, most of the seismic design
work cannot describe the actual structure behavior, as very significant differences
exist between the predicted and the actual response. The reason for these
differences is due to the neglecting of the influence of ground motion types. The
code provisions classify the earthquakes only in function of their magnitudes and
specific spectra. Therefore, a structure designed for a given magnitude and soil
conditions, behaves in the same manner, regardless of whether it is situated in a
zone influenced by interplate, intraplate or intraslab sources. This is clearly not
true. This is a great mistake of the present codes, the structure behavior being very
different for these sites, even if the magnitudes are the same. Therefore, the seismic
design methodology must take into account these differences.