1. Ph.D. Candidate, Dept. of Civil Engineering, King Mongkut’s Univ. of Technology Thonburi, Khet Thung Khru, Bangkok 10140, Thailand.
2. Associate Professor, Dept. of Civil Engineering, King Mongkut’s Univ. of Technology Thonburi, Khet Thung Khru, Bangkok 10140, Thailand (corresponding author).