1. Assistant Professor, Dept. of Civil and Architectural Engineering, Sultan Qaboos Univ., P.O. Box 33, Muscat 123, Sultanate of Oman (corresponding author).
2. Professor, Dept. of Civil Engineering, Tohoku Univ., Aoba 06, Sendai 980-8579, Japan.
3. Research Engineer, Dept. of Civil Engineering, Tohoku Univ., Aoba 06, Sendai 980-8579, Japan.
4. Civil Engineer, CTI Engineering Co. Ltd., 2-15-1 Honcho, Sendai 980-0014, Japan.