Lessons Learned from past Earthquakes

The development of design seismic forces is reviewed. The earthquake engineering was shown to have developed in the last 60 years. The characteristics of ground motion and structural response were gradually understood over the last five decades. The damage statistics from recent major earthquakes indicated that the severe damage was observed in taller buildings. The ratios of buildings with operational damage were as high as 90 percent because predominant buildings were low-rise buildings and such low-rise buildings suffered much less damage. Contrary to the statistics, the nonlinear response analysis results showed higher ductility demand (damage) to low-rise buildings. Causes of earthquake damage are briefly discussed for reinforced concrete buildings. A large number of problems have been solved in research community. It is essential for the disaster reduction that the information in research domain should be transferred to the engineering community and implemented in engineering practice. The future direction of earthquake engineering is discussed in terms of structural engineering.