1. School of Civil Engineering and Transportation, State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou 510640, P. R. China
2. The State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, P. R. China
3. Department of Mechanics and Civil Engineering, Jinan University, Guangzhou 510632, P. R. China