Increased awareness of the economic and social effects of aging, deterioration and extreme events on civil infrastructure has been accompanied by recognition of the need for advanced structural health monitoring and damage detection tools. Today, these tasks are done by visual inspection and very traditional methods such as the tap test. This labor-intensive task is done at a frequency of less than once every two years for bridges, and on an as-needed basis for other infrastructures such as buildings. Structural health monitoring techniques based on changes in dynamic characteristics have been studied for the last three decades. When the damage is substantial, these methods have some success in determining if damage has occurred. At incipient stages of damage, however, the existing methods are not as successful. A number of new research projects have been funded to improve the damage detection methods including the use of innovative signal processing, new sensors, and control theory. This survey paper highlights these new research directions.

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This paper presents several major developments and research initiatives of NSF's program in earthquake hazard mitigation. These activities include (1) establishment of three new earthquake engineering research centers in the U.S., (2) initiation of a major five-year cooperative research program on urban earthquake disaster mitigation between the U.S. and Japan, (3) initiation of two joint center-to-center projects between the U.S. and Japan, and (4) planning for a high-performance earthquake simulation facility network in the U.S. These activities highlight the ever-increasing importance of research innovations for earthquake disaster mitigation and the continuing challenges for cooperation between the U.S. and Japan.

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