1. Professor, Dept. of Civil Engineering, Univ. of Hong Kong, Pokfulam Rd., Hong Kong, China.
2. Assistant Professor, Dept. of Civil Engineering, ICIST, Instituto Superior Técnico, Technical Univ. of Lisbon, 1049-001 Lisbon, Portugal.
3. Professor, Dept. of Civil Engineering, ICIST, Instituto Superior Técnico, Technical Univ. of Lisbon, 1049-001 Lisbon, Portugal (corresponding author).