[1] Univ Hong Kong, Dept Civil Engn, Hong Kong, Hong Kong, Peoples R China
[2] Univ Sci & Technol China, Dept Math, Hefei 230026, Peoples R China
[3] Brown Univ, Div Appl Math, Providence, RI 02912 USA
[4] Shanghai Univ, Shanghai Inst Appl Math & Mech, Shanghai 200072, Peoples R China
[5] Hong Kong Polytech Univ, Dept Civil & Struct Engn, Hong Kong, Hong Kong, Peoples R China