1. Assistant Professor, Dept. of Civil Engineering and Architecture, Instituto Superior Técnico, Technical Univ. of Lisbon, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal (corresponding author).
2. Associate Professor, Center for Management Studies (CEG-IST), Technical Univ. of Lisbon, Avenida Rovisco Pais, 1049-001 Lisbon, Portugal.