1. Assistant Professor, Dept. of Civil Engineering, Univ. of Minho, Campus de Azurém, 4810-058 Guimarães, Portugal (corresponding author). E-mail: jsena@civil.uminho.pt
2. Associate Professor, Dept. of Civil Engineering, Univ. of Minho, Campus de Azurém, 4810-058 Guimarães, Portugal. E-mail: barros@civil.uminho.pt
3. Professor, Dept. of Civil Engineering, Indian Institute of Technology Madras, Chennai 600036, India. E-mail:gettu@iitm.ac.in
4. Assistant Professor, Dept. of Civil Engineering, Univ. of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal. E-mail: alvaro@fe.up.pt