1. Associate Professor, Dept. of Civil Engineering, The Univ. of Hong Kong, Pokfulam Rd., Hong Kong (corresponding author). E-mail: tstng@hkucc.hku.hk
2. MPhil Candidate, Dept. of Civil Engineering, The Univ. of Hong Kong, Pokfulam Rd., Hong Kong. E-mail: h0595510@hkusua.hku.hk