Advances in Seismic Design Methodologies - Earthquake Engineering for Structural Design - page 394

394 Earthquake Engineering for Structural Design

Vision 2000, these minimum levels are four, but in the design practice this
methodology can be used only for very important buildings, for very strong
earthquakes and for special demands of building owners.
For current cases, the checks required to guarantee the good behavior of a structure
during an earthquake must be examined in the light of multi-level base seismic design,
which is limited, from practical reasons, at maximum three levels. Due to the fact that
a specific analysis must be performed for each level, no one designer will accept more
than two or maximum three levels for the structure design.
In the seismic load-top displacement curve (Fig. 9.1), there are three very important
points:
- Limit of elastic behavior without any damage.

- Limit of damage with major damage.

- Limit of collapse, for which the structure is at the threshold of breakdown.

Figure 9.2 Performance objectives (Gioncu and Mazzolani, 2002)