1. Junior Researcher, National Laboratory of Civil Engineering, Avenue do Brasil, 1700-066 Lisbon, Portugal.
2. Civil Engineer, Senior Researcher, National Laboratory of Civil Engineering, Avenue do Brasil, 1700-066 Lisbon, Portugal.
3. Full Professor, Dept. of Civil Engineering and Architecture, Instituto Superior Técnico, Technical Univ. of Lisbon, 1049-001 Lisbon, Portugal (corresponding author).