1. Ph.D. Student, Faculty of Engineering, Univ. of Bristol, Queen’s Bldg., Bristol BS8 1TR, U.K. (corresponding author).
2. Lecturer, Faculty of Engineering, Univ. of Bristol, Queen’s Bldg., Bristol BS8 1TR, U.K.
3. Emeritus Professor, Division of Civil Engineering Fulton Bldg., H13 Univ. of Dundee Nethergate, Dundee DD1 4HN, U.K.
4. Lecturer, Faculty of Engineering, Dept. of Civil Engineering, Edmundo Larenas 215, Barrio Universitario, Concepción 4089100, Chile.
5. Senior Research Fellow, Faculty of Engineering, Univ. of Bristol, Queen’s Bldg., Bristol BS8 1TR, U.K.