1. Guest Associate Professor, Dept. of Civil Engineering, Shanghai Jiao Tong Univ., 800 Dongchuan Rd., Minhang District, Shanghai 200240, China (corresponding author).
2. Professor, Dept. of Civil Engineering, National Taipei Univ. of Technology, Taipei, Taiwan 10608.
3. Graduate Student, Dept. of Civil Engineering, National Taipei Univ. of Technology, Taipei, Taiwan 10608.