1. Professor, School of Civil Engineering, Shandong Univ., Jinan 250061, China.
2. Ph.D. Candidate, School of Civil Engineering, Shandong Univ., Jinan 250061, China.
3. Associate Professor, School of Civil Engineering, Qingdao Univ. of Technology, Qingdao 266033, China.
4. Professor, School of Civil Engineering, Shandong Univ., Jinan 250061, China (corresponding author).