1. Ph.D. Student, Dept. of Civil, Building and Environmental Engineering with Information Technology and Applied Mathematics, Univ. of Messina, Villaggio S. Agata, 98166 Messina, Italy.
2. Full Professor, Dept. of Civil, Building and Environmental Engineering with Information Technology and Applied Mathematics and Inter-University Centre of Theoretical and Experimental Dynamics, Univ. of Messina, Villaggio S. Agata, 98166 Messina, Italy (corresponding author).