1. Senior Researcher, Dept. of Civil and Environmental Engineering, Univ. of Catania, Viale A. Doria 6, 95125 Catania, Italy (corresponding author).
2. Full Professor, Dept. of Civil and Environmental Engineering, Univ. of Catania, Viale A. Doria 6, 95125 Catania, Italy.
3. Ph.D. Student, Dept. of Civil and Environmental Engineering, Univ. of Catania, Viale A. Doria 6, 95125 Catania, Italy.