1. Associate Professor, Dept. of Civil and Environmental Engineering, Yamaguchi Univ., Ube, Yamaguchi 755-8611, Japan (corresponding author).
2. Ube Machinery Co., Ltd., Industrial Machinery Bridge & Steel Structure Headquarters, 1980 Okinoyama Kogushi, Ube, Yamaguchi 755-8633, Japan.
3. Associate Professor, Dept. of Civil Engineering, Univ. of Colorado, Denver, CO 80217.
4. Assistant Professor, Dept. of Civil and Environmental Engineering, Kure National College of Technology, Kure, Hiroshima 737-8506, Japan.