Earthquake engineering in the 1990s : achievements, concerns and future directions

The period since the First World Conference on Earthquake Engineering in 1956 has seen a tremendous increase in the ability of engineers to produce designs that will reliably withstand the effects of strong ground shaking. This ability arises from: first, improved knowledge of the nature of earthquake processes and of how structures respond to seismic loading; second, from the development of new structural systems with enhanced ability to withstand earthquakes; and, thirdly, from improved analytical techniques. This progress is demonstrated by the greatly superior performance in major earthquakes of structures built in the last few decades, compared with those of earlier periods. Examples of this superior performance were seen in the 1994 Northridge, California, and 1995 Kobe, Japan, events. Nevertheless, both these earthquakes revealed significant gaps in present knowledge. This paper provides a personal view of the achievements in earthquake engineering in the past decade, particularly with respect to building design. It addresses some of the gaps in knowledge and reviews possible future directions.