1. Engineer, Centrais Elétricas Brasileiras S.A., Rio de Janeiro?RJ, CEP 20040-030, Brazil (corresponding author); formerly, D.Sc. Student, COPPE?Federal Univ. of Rio de Janeiro, Rio de Janeiro?RJ, CEP 21941-596, Brazil.
2. Professor, Dept. of Civil and Environmental Engineering, Chalmers Univ. of Technology, SE-412 96 Göteborg, Sweden.
3. Professor, POLI–Federal Univ. of Rio de Janeiro, Rio de Janeiro–RJ, CEP 21941-909, Brazil.
4. Professor, COPPE–Federal Univ. of Rio de Janeiro, Rio de Janeiro–RJ, CEP 21941-569, Brazil.