1. Graduate School of Engineering, Hokkaido University, N13W8Sapporo, 501-1193, Japan
2. Department of Civil Engineering, Gifu University, 1-1 Yanagido, Gifu501-1193, Japan
3. Department of Architecture and Civil Engineering, Toyohashi University of Technology, TempakuchoToyohashi, Aichi 441-8580, Japan