6. Modification of the site effect

Seismic protection of structures is usually achieved by sizing them to withstand the stresses caused by earthquakes. Another way of meeting seismic protection objectives for a structure is to act on the seismic movement to which it is subjected.

The aim of reducing the site effect is not necessarily to build a non-seismic building in a zone where seismic movement would be rendered zero. It is more important to consider situations where the design conditions of a structure or its equipment are slightly exceeded, and where it is more economical to act on the site effect than to adapt the structure or equipment.

This may be particularly the case for new structures built on a standardized basis, or for the re-evaluation of existing structures. Depending on the situation (figure