1. Dept. of Civil Engineering, Univ. of Calabria, 87036 - Rende, Cosenza, IT (Corresponding author), e-mail: teresa.iuele@unical.it
2. Dept. of Civil Engineering, Univ. of Calabria, 87036 - Rende, Cosenza, IT, e-mail: vaiana@unical.it
3. Dept. of Civil Engineering, Univ. of Calabria, 87036 - Rende, Cosenza, IT, e-mail: vincenzo.gallelli@unical.it
4. Dept. of Civil Engineering, Univ. of Calabria, 87036 - Rende, Cosenza, IT, e-mail: f.demasi@unical.it