1. College of Rail Transportation, Shenzhen Univ., Shenzhen Key Laboratory of Urban Rail Transit, Shenzhen 518060, China (corresponding author).
2. Associate Professor, Dept. of Civil Engineering, Santa Clara Univ., Santa Clara, CA 95053.
3. Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China.
4. Assistant Professor, Dept. of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180.
5. Professor, Dept. of Civil and Environmental Engineering, Univ. of Wisconsin-Madison, Madison, WI 53706.