  A novel geomechanics concept is presented for studying the behavior of
geomaterials and structures by capturing the underlying dynamics as
realistically as possible for earthquake excitation applied in time domain.
Enormous amount of damages caused to infrastructures during recent earthquakes
in all over the world indicate that there is a considerable room for
improvement. Causes for extensive damages are generally attributed to poor soil
conditions at the region. It is interesting to note that all structures in a
region with poor soil condition do not suffer similar damages; in fact, some of
them remain damage-free. There are many reasons for this including inability to
model the soil-structural systems properly, predict the future design
earthquake time history at the site, model the dynamic amplification of
responses caused by the excitation, incorporate major sources of nonlinearity
and energy dissipation, and most importantly consider the presence of a
considerable amount of uncertainty at every phase of the evaluation process.
The most recent research trend is to capture complicated behavior by conducting
multiple deterministic analyses by taking advantage of current significantly
improved computational capability. By conducting few dozens of deterministic
analyses at very intelligently selected points, structures can be designed more
seismic load-tolerant. The performance based seismic design concept recently
introduced in the U.S. is showcased in this paper. The requirements in the
guidelines appear to be reasonable. The concept is expected to change the
current engineering design paradigm. The authors believe that the proposed
alternatives to the simulation and the basic random vibration concept.
