1. Professor, School of Civil Engineering, Shandong Univ., Jinan, Shandong 250061, China.
2. Associate Professor, School of Civil Engineering, Shandong Univ., Jinan, Shandong 250061, China (corresponding author).
3. Graduate Student, School of Civil Engineering, Shandong Univ., Jinan, Shandong 250061, China.