1. a Department of Structures, Water and Soil , University of L'Aquila , 67040, Monteluco di Roio, L'Aquila, Italy E-mail:
2. b Department of Structures, Water and Soil , University of L'Aquila , 67040, Monteluco di Roio, L'Aquila, Italy
3. c On sabbatical at Department of Bioengineering , Imperial College of London , UK E-mail:
4. d Department of Structures, Water and Soil , University of L'Aquila , 67040, Monteluco di Roio, L'Aquila, Italy E-mail: