Advances in Seismic Design Methodologies - Earthquake Engineering for Structural Design - page 404

404 Earthquake Engineering for Structural Design

- Very low seismicity, accelerations less than 0.08g.
- Low seismicity, acceleration less than 0.20g.
- Moderate seismicity, accelerations less than 0.32g.
- High seismicity, accelerations less than 0.50g.
- Strong seismicity, accelerations larger than 0.50g.
The building can be framed in two main typologies:
- Ordinary , when the damage occurring during an earthquake does not produce
important disturbance in the community;
- Important, when damage or collapse can produce important social perturbations.
In spite of these differences, the current seismic design methodologies propose the
same procedures to be followed in all seismic zones. It should be logical to spend more
design effort on obtaining structures, that adequately perform in zones of high
seismicity and for important buildings. Contrary, less design effort must be required for
zones of low seismicity and for ordinary buildings.
Considering these aspects, a strategy is proposed by Truta et al (2003) in order to
reduce the design effort:

Building Seismicity

Verylow Low Moderate High Strong

Ordinary 1L 2L 2L 3L 3L

Important 2L 2L 3L 3L 4L

For very low seismicity and ordinary buildings, the design can consider only one
level. For very low seismicity, but important buildings and low seismicity or moderate
seismicity, but ordinary buildings, two levels must be considered. Three levels are
required for moderate seismicity and important buildings or always for high seismicity
or for strong seismicity and ordinary buildings. Four levels must be used only for
strong seismicity and important buildings.

9.4RESPONSE SPECTRA ASREPRESENTATIONOFGROUND
MOTIONS

9.4.1 Response SpectrumTypes

Since the concept of response spectrum was introduced into Earthquake Engineering,
this technique has been widely used to estimate force and deformation demands, which
are imposed on structures by the earthquake ground motions. Today, response spectra