1. Professor, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, Number 43, Section 4, Keelung Rd., Taipei 106, Taiwan, Republic of China.
2. Lecturer, Faculty of Building and Industrial Construction, National Univ. of Civil Engineering, Number 55, Giai Phong Rd., Hanoi, Vietnam; formerly, Ph.D. Student, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, Number 43, Section 4, Keelung Rd., Taipei 106, Taiwan, Republic of China (corresponding author).