1. Professor, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, No. 43 Section 4 Keelung Rd., Taipei 106, Taiwan (corresponding author).
2. Associate Professor, Dept. of Civil Engineering, National Taipei Univ. of Technology, No. 1, Section 3, Chung-Hsiao East Rd., Taipei 106, Taiwan.
3. Associate Professor, Dept. of Civil Engineering, National Ilan Univ., No. 1, Section 1, Shen-Lung Rd., I-Lan 260, Taiwan.