1. Professor, Dept. of Highway and Railway Engineering, College of Transportation, Southeast Univ., 2#Sipailou, Nanjing, Jiangsu 210096, China.
2. Assistant Professor, Dept. of Civil Engineering, College of Science, Nanjing Univ. of Science and Technology, Nanjing, Jiangsu 210094, China.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Tennessee, 419 John D. Tickle Engineering Bldg., 851 Neyland Dr., Knoxville, TN 37996.
4. Associate Professor, Dept. of Highway and Railway Engineering, College of Transportation, Southeast Univ., 2#Sipailou, Nanjing, Jiangsu 210096, China (corresponding author).