1. Professor, Dept. of Civil and Environmental Engineering, Univ. of Perugia, via Duranti 93, 06125 Perugia, Italy.
2. Ph.D. Researcher, Dept. of Civil and Environmental Engineering, Univ. of Perugia, via Duranti 93, 06125 Perugia, Italy (corresponding author).
3. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Perugia, via Duranti 93, 06125 Perugia, Italy.