Load combination of aftershocks and tsunami for tsunami-resistant design

Choi, B.  ; Nishida, Akemi  ; Itoi, Tatsuya*; Takada, Tsuyoshi*  

Occurrence of huge tsunami and numerous aftershocks are expected after a gigantic subduction earthquake occurs. Therefore, the important coastal structures (nuclear power plants etc.) must be designed against tsunami as well as ground shaking. When the action effects both from aftershocks and tsunami to the structure occur simultaneously, practically reasonable assessment of load combination from aftershocks and tsunami is needed. In order to treat the load combination problem reasonably, stochastic load combination technique can be used, which requires stochastic modeling of action effects from aftershocks and tsunami. Next, the reliability analysis follows, where load and resistance factors can be obtained under the condition that the conditional target reliability for a limit state function is given. This method is demonstrated at some sites in Japan. Finally, load and resistance factor design format for the tsunami-resistant design is proposed.