1. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Florence, via S. Marta 3, 50139 Firenze, Italy.
2. Professor, Dept. of Civil and Environmental Engineering, Univ. of Florence, via S. Marta 3, 50139 Firenze, Italy.
3. Researcher, Dept. of Civil and Environmental Engineering, Univ. of Florence, via S. Marta 3, 50139 Firenze, Italy (corresponding author).