1. Ph.D. Student, Dept. of Civil and Environmental Engineering DICEA, Univ. of Florence, Via di S. Marta, 3 - 50139 Firenze (FI), Italy (corresponding author).
2. Research Fellow, Dept. of Civil and Environmental Engineering DICEA, Univ. of Florence, Via di S. Marta, 3 - 50139 Firenze (FI), Italy.
3. Associate Professor, Dept. of Civil and Environmental Engineering DICEA, Univ. of Florence, Via di S. Marta, 3 - 50139 Firenze (FI), Italy.
4. Full Professor, Dept. of Civil and Environmental Engineering DICEA, Univ. of Florence, Via di S. Marta, 3 - 50139 Firenze (FI), Italy.