1. Ph.D. Lecturer, Dept. of Civil and Natural Resources Engineering, Univ. of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand (corresponding author).
2. Professor, Dept. of Civil and Structural Engineering, Univ. of Sheffield, Sir Frederick Mappin Building, Mappin St., Sheffield S1 3JD, U.K.
3. Professor, School of Architectural Studies, Univ. of Sheffield, The Arts Tower, Western Bank, Sheffield S10 2TN, U.K.