1. Research Fellow, Dept. of Civil Engineering, Design, Building and Environment, Second Univ. of Napoli, Via Roma 29, 81031 Aversa, Italy (corresponding author).
2. Professor, Dept. of Structural and Geotechnical Engineering, Sapienza Univ. of Roma, Via Eudossiana 18, 00184 Roma, Italy.
3. Full Professor, Dept. of Civil Engineering, Design, Building and Environment, Second Univ. of Napoli, Via Roma 29, 81031 Aversa, Italy.