Dionysius Siringoringo

A great number of long-span bridges were constructed in Japan in the past decades. These bridges, especially the cable-supported ones, are expensive to inspect and maintain. They have long service periods of over 100 years, during which they inevitably suffer from environmental long-term loads effects such as fatigue, material deterioration and other extreme load effects. Governments, bridge authorities, as well as scientists and engineers, are now very much concerned with the issues of health, durability, and safety of these major bridges in a long-term service period. Structural health monitoring (SHM), therefore, becomes an increasingly important, and more concerted efforts are now being devoted to enhance our understanding in implementation of both monitoring technologies and methodologies.
The process of instrumentation, measurement and analysis of bridge response are essential parts of health monitoring. The importance of bridge SHM has been emphasized especially after the 1995 Kobe earthquake. As we know, prior to the 1995 Hyogo-ken Nanbu (Kobe) earthquake, many longspan bridges including the Honshu-Shikoku bridges were designed and constructed using the specified ground motions that were far smaller than the near-field ground motions experienced during Kobe earthquake. To anticipate similar ground motions as experienced in Kobe the bridge seismic design code was later revised. And accordingly the seismic retrofit program of existing bridges has also started.

In the context of retrofitting and evaluation of performance of the existing bridges, instrumentation and monitoring system play important roles. Fortunately, most long-span bridges were instrumented with sensor system that captures bridge responses to various types of motion such as ambient, traffic and earthquakes. Using these responses and by applying a proper analysis, the real performance of a bridge can be evaluated.

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