1. Dept. of Civil and Environmental, Faculty of Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1010, New Zealand (corresponding author).
2. Senior Lecturer, Dept. of Civil and Environmental, Faculty of Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
3. Professor, Dept. of Civil and Environmental, Faculty of Engineering, Univ. of Auckland, Private Bag 92019, Auckland 1010, New Zealand.