1. Professor, Key Laboratory of Concrete and Prestressed Concrete Structures of the Ministry of Education, Southeast Univ., Nanjing 210096, P. R. China (corresponding author).
2. Postgraduate Researcher, School of Civil Engineering, Southeast Univ., Nanjing 210096, P. R. China.
3. Professor, School of Architecture and Civil Engineering, Jiangsu Univ. of Science and Technology, Zhenjiang 212003, P. R. China.