1. Engineering and Design Manager, Spanbild Projects, 112 Waterloo Rd., P.O. Box 11013, 8443 Christchurch, New Zealand.
2. Lecturer, Dept. of Civil Engineering, Univ. of Canterbury, Private Bag 4800, 8041 Christchurch, New Zealand (corresponding author).
3. Professor, Dept. of Civil Engineering, Univ. of Canterbury, Private Bag 4800, 8041 Christchurch, New Zealand.
4. Structural Engineer, Building Research Association of New Zealand, 1222 Moonshine Rd., Private Bag 50908, 5381 Porirua, New Zealand.