1. Postdoctoral Fellow, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, #43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, R.O.C. (corresponding author). E-mail: sryang@mail.ntust.edu.tw
2. Professor, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, #43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, R.O.C. E-mail: hdlin@mail.ntust.edu.tw
3. Ph.D. Student, Dept. of Construction Engineering, National Taiwan Univ. of Science and Technology, P.O. Box 117-653, Taipei 106, Taiwan, R.O.C. E-mail: johnsonlive@yahoo.com.tw
4. Professor, Dept. of Civil Engineering, National Central Univ., Jungli, Taoyuan, 32054, Taiwan, R.O.C. E-mail: t321655@ncu.edu.tw