ABSTRACT
The 1995 Kobe earthquake, the 2011 Tohoku offshore earthquake, and the 2016 Kumamoto earthquake stroked bridges and caused extensive damages and collapse. All these earthquakes were unexpectedly large, and the design codes were forced to be revised to cover these earthquakes. To prevent further catastrophic disasters in future, seismic design covering all levels of ground motion intensity, and not just a few selected levels such as the design-based level or the most considered level, should be considered. Recently, incremental dynamic analysis (IDA) is becoming a normally acceptable tool for seismic design. Using the fragility from IDA, risk assessment can be conducted with consideration of probability of hazard cost of restoring functions of damaged members. Key structural components like isolation and damping devices can be optimized by using the seismic risk analysis, and retrofitting plans can be evaluated by seismic life cycle cost (LCC) to choose the most economical solution. Basic concept of IDA, fragility, risk analysis, and LCC for seismic design of bridge is introduced. Application benchmarks are also introduced in this chapter.
