1. Lecturer, Dept. of Civil Engineering, Univ. of Nottingham, University Park, Nottingham, UK, NG7 2RD (corresponding author).
2. Senior Lecturer, Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Technion City, 32000 Haifa, Israel.
3. Professor, Dept. of Engineering, Univ. of Cambridge Trumpington Street, Cambridge CB2 1PZ.