1. Professor, Dept. of Structural Engineering, Univ. “La Sapienza,” via Eudossiana, 18, 00184 Roma, Italy.
2. Postdoctoral Student, Dept. of Structural Engineering, Univ. of Basilicata, C.da Macchia Romana, 85100 Potenza, Italy.
3. Assistant Professor, Dept. of Structural Engineering, Univ. of Basilicata, C.da Macchia Romana, 85100 Potenza, Italy (corresponding author).