1. Professor, Dept. of Civil Engineering, National Cheng Kung Univ., Tainan 701, Taiwan (corresponding author).
2. Postdoctoral Fellow, Dept. of Civil Engineering, National Cheng Kung Univ., Tainan 701, Taiwan.
3. Ph.D. Candidate, Dept. of Civil Engineering, National Cheng Kung Univ., Tainan 701, Taiwan.