1. Associate Professor, School of Mechanics and Engineering Science, Zhengzhou Univ., Zhengzhou 450001, China (corresponding author).
2. School of Mechanics and Engineering Science, Zhengzhou Univ., Zhengzhou 450001, China.
3. Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Houghton, MI 49931-1295.
4. Professor, Dept. of Civil and Environmental Engineering, Michigan Technological Univ., 1400 Townsend Dr., Houghton, MI 49931-1295.