1. Associate Professor, Dept. of Civil Engineering, Faculty of Engineering, Chulalongkorn Univ., Phayathai Rd., Pathumwan, Bangkok 10330, Thailand (corresponding author).
2. Associate Professor, Dept. of Civil Engineering, Faculty of Engineering, Chulalongkorn Univ., Phayathai Rd., Pathumwan, Bangkok 10330, Thailand.
3. Design Engineer, VSL (Thailand) Co., Ltd., No. 1168/14, Lumpini Tower, Rama IV Rd., Thungmahamek, Sathon, Bangkok 10120, Thailand.