1. Ph.D. Candidate, School of Civil Engineering, Shandong Univ., Jinan 250061, China.
2. Professor, School of Civil Engineering, Shandong Univ., Jinan 250061, China (corresponding author).
3. Master, School of Civil Engineering, Shandong Univ., Jinan 250061, China.
4. Research Engineer, Dept. of Civil and Environmental Engineering, National Univ. of Singapore, Singapore 117576.