1. Politecnico di Milano, School of Civil and Environmental Engineering, 32 Piazza Leonardo Da Vinci, Milan 20133, Italy (corresponding author).
2. Full Professor, Politecnico di Milano, School of Civil and Environmental Engineering, 32 Piazza Leonardo Da Vinci, Milan 20133, Italy.
3. Associate Professor, Univ. of Minho, Dept. of Civil Engineering, Guimarães 4800-058, Portugal.
4. Full Professor, Univ. of Minho, Dept. of Civil Engineering, Guimarães 4800-058, Portugal.