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). E-mail: consoli@ufrgs.br
2. 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.
3. Associate Professor, Dept. of Transportation, Federal Univ. of Ceará, Campus Universitário do Pici, Bloco 710, CEP 60455-760 Fortaleza, Ceará, Brazil.
4. Professor, Dept. of Civil Engineering, Imperial College, Univ. of London, London, SW7 2AZ, UK.