1. Associate Professor, Highway College, Chang’an Univ., Xi’an, Shaanxi 710064, China (corresponding author).
2. Assistant Professor, Highway College, Chang’an Univ., Xi’an, Shaanxi 710064, China.
3. Professor, Dept. of Civil and Environmental Engineering, Louisiana State Univ., Baton Rouge, LA 70803.
4. Associate Professor, Dept. of Civil and Environmental Engineering, Colorado State Univ., Fort Collins, CO 80523.