1. Faculty of Environmental Eng. The University of Kitakyushu Kitakyushu‐shi Fukuoka Japan
2. The University of Kitakyushu Kitakyushu‐shi Fukuoka Japan
3. Kajima Technical Research Institute Chofu‐shi Tokyo Japan
4. Japanese Society of Steel Construction Chuo‐ku Tokyo Japan
5. Chiba University Chiba‐shi Chiba Japan