1. Assistant Professor, Dept. of Civil Engineering, ISISE, Univ. of Minho, Azurém, P-4800-058 Guimarães, Portugal (corresponding author).
2. Former Ph.D. Student, Dept. of Civil Engineering, ISISE, Univ. of Minho, Azurém, P-4800-058 Guimarães, Portugal.
3. Professor, Dept. of Civil Engineering, ISISE, Univ. of Minho, Azurém, P-4800-058 Guimarães, Portugal.