1. Res. Assoc., Dept. of Civ. and Struct. Engrg., The Univ. of Sheffield, Sheffield, S1 3JD, U.K. E-mail: z.huang@sheffield.ac.uk
2. Reader, Dept. of Civ. and Struct. Engrg., The Univ. of Sheffield, Sheffield, S1 3JD, U.K.
3. Prof., School of Arch. Studies, The Univ. of Sheffield, Sheffield, S10 2TN, U.K.