1. Research Associate, Dept. of Structural Engineering, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy (corresponding author). E-mail: biondini@stru.polimi.it
2. Professor, Dept. of Structural and Geotechnical Engineering, Univ. of Rome “La Sapienza,” Via Eudossiana 18, 00184 Rome, Italy. E-mail: franco.bontempi@uniroma1.it
3. Professor, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, CB 428, Boulder, CO 80309-0428. E-mail: dan.frangopol@colorado.edu
4. Professor, Dept. of Structural Engineering, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milan, Italy. E-mail: malerba@stru.polimi.it