1. Postdoctoral Researcher, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
2. Full Professor, College of Architecture and Civil Engineering, Beijing Univ. of Technology, Beijing 100124, China (corresponding author).
3. Full Professor, College of Architecture and Civil Engineering, Beijing Univ. of Technology, Beijing 100124, China.
4. Full Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.