1. Department of Engineering Mechanics, School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, P. R. China
2. College of Mechanics and Materials, Hohai University, No. 1 Xikang Road, Nanjing, Jiangsu 210098, P. R. China
3. Department of Civil and Natural Resources Engineering, University of Canterbury, Christchurch 8041, New Zealand