1. Associate Professor, Dept. of Civil Engineering, Federal Univ. of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3 Andar, CEP 90035-190 Porto Alegre, Rio Grande do Sul, Brazil (corresponding author).
2. Associate Professor, Faculty of Engineering, Univ. of Porto, Rua Dr. Roberto Frias, s/n, 4200-465 Porto, Portugal.
3. Research Fellow, Dept. of Civil Engineering, Federal Univ. of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3 Andar, CEP 90035-190 Porto Alegre, Rio Grande do Sul, Brazil.
4. Adjunct Professor, Dept. of Civil Engineering, Federal Univ. of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3 Andar, CEP 90035-190 Porto Alegre, Rio Grande do Sul, Brazil.