1. Research Engineer, Life Cycle Management Research Center, Port and Airport Research Institute, Yokosuka 239-0826, Japan. E-mail: dai@pari.go.jp
2. Professor, Division of Built Environment, Hokkaido Univ., Sapporo, 060-8628, Japan. E-mail: ueda@eng.hokudai.ac.jp
3. Associate Professor, Division of Built Environment, Hokkaido Univ., Sapporo, 060-8628, Japan. E-mail: ysato@eng.hokudai.ac.jp