1. Teaching and Research Fellow, Dept. of Civil and Environmental Engineering, Faculty of Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand (corresponding author).
2. Senior Lecturer, Dept. of Civil and Environmental Engineering, Faculty of Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
3. Professor, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand.