Learning from Earthquakes - Earthquake Engineering for Structural Design - page 95

- Special strategy must be developed for seismic zones with rare and

moderate earthquakes, where some simplified design methodologies can
be adequate to assure a reduced seismic risk.

3.5 LESSONSFOR SEISMICDESIGN

3.5.1 TwoCrucial Events inSeismic Design Philosophy

On April 1906 one of the greatest earthquakes shocked San Francisco, California,
killing 1000 persons and causing a high damage for that time. A dramatic image of
the consequences of this earthquake on the means of conveyance of this time, the
horse carts, is presented in Figure 3.22. This event was very significant because it
represented the starting of the first scientific attempt to understand the role of the
existing geological Californian fault in generating earthquakes.
A group of creative engineers, responding to the observed damage of this
earthquake, started to study, conceive and design a progression of structural
solutions to solve the earthquake problem. This creative work has extended over a
100-year period and continues today.
A brief progression of key milestones in seismic design history follows
(Elsessner, 2004):
- the initial seismic design for buildings was based on the similarity with

static wind loads;

- in the early 1930s the concept of building dynamic response and the

importance of building periods gained some interest;

Figure 3.22 Dramatic picture with horses killed during the 1906 San Francisco
earthquake (USGS, nd)