1. College of Civil Engineering, Hunan Univ., Lushan Rd. (S), Yuelu District Changsha, Hunan Province 410082, China.
2. Professor, College of Civil Engineering, Hunan Univ., Lushan Rd. (S), Yuelu District Changsha, Hunan Province 410082, China (corresponding author).
3. School of Civil Engineering and Architecture, Zhejiang Sci-Tech Univ., Wenze Rd. (S), Jianggan District Hangzhou, Zhejiang Province 310018, China.