1. Senior Lecturer, Univ. of Canterbury, Christchurch 8140, New Zealand (corresponding author).
2. Inaugural Zachry Professor, Zachry Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136.
3. Distinguished Professor, Dept. of Mechanical Engineering, Univ. of Canterbury, Christchurch 8140, New Zealand.
4. Professor, Dept. of Civil Engineering, Univ. of Canterbury, Christchurch 8140, New Zealand.