1. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
3. Lecturer, Dept. of Civil and Environmental Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1142, New Zealand.