1. Civil Engineering, Instituto Superior Técnico (IST), Technical Univ. of Lisbon, Portugal; and ENGECONSULT, Consultores Técnicos Ltda, Rua Xavier Marques, 94, Aflitos, Recife, CEP 52050-230, Brazil.
2. Associate Professor, Dept. of Civil Engineering, Instituto Superior Técnico, Technical Univ. of Lisbon, IST, SHRHA, Av. Rovisco Pais, 1049-001 Lisboa, Portugal (corresponding author).