1. Professor, Dept. of Civil Engineering, National Taiwan Univ., 1, Sect. 4, Roosevelt Rd., Taipei 10617, Taiwan, ROC.
2. Assistant Professor, Dept. of Civil Engineering, National Chi-Nan Univ., 1 University Rd., Puli, Nantou 54561, Taiwan, ROC (corresponding author).
3. Former Graduate Student, Dept. of Civil Engineering, National Taiwan Univ., 1, Sect. 4, Roosevelt Rd., Taipei 10617, Taiwan, ROC.
4. Professor, Dept. of Civil Engineering, National Univ. of Singapore, 21 Lower Kent Ridge Rd., Singapore 119077; and, Board Member of TBTC, National Taiwan Univ. of Science and Technology, 43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, ROC.