Abstract

Earthquakes have been devastating all over the globe. Earthquakes have not only caused strange problems, but
many of the behaviors of structures during earthquake are difficult to understand. Very strong and stable structures
are found to be vulnerable sometimes. Tall structures on some occasions have performed better than short structures
making the researchers to think beyond the quality of structures. Many times, the ground condition at the site plays
a significant role in controlling the performance of structures resting on it. The ground condition at the site is
termed as “site effect” and proper characterization of site is necessary to analyze the structures for their seismic
performance. This paper discusses the relevance of site characterization with examples and presents the summary
of some of the earlier works of the authors regarding site characterization. The effect of Bhuj earthquake of 2001
on buildings in Ahmedabad far off from epicenter is presented. Resonance effect and amplification in ground
motion are considered major culprits for damage to more than 100 buildings in Ahmedabad. More accurate
method of assessing the natural frequency of ground is necessary for which a simplified and effective approach
suggested by authors is presented. Input for such evaluations is shear wave velocity of soil. Many times, it is
difficult to determine shear wave velocity at a site. Hence, the author’s contribution of summarizing shear wave
velocity from standard penetration number is discussed. In summary, rational and simplified methods of analysis
with simple input data are more effective to understand the ground behavior during earthquakes. For decades,
such studies have been attempted by many researchers to refine the understanding of actual ground behavior
during earthquakes.