1. Assistant Professor, Dept. of Civil Engineering, Univ. of Coimbra, R. Luís Reis Santos, 3030-788 Coimbra, Portugal (corresponding author).
2. Assistant Professor, Dept. of Civil Engineering, Univ. of Coimbra, R. Luís Reis Santos, 3030-788 Coimbra, Portugal.
3. Civil Engineer, R. da Liberdade, 97, 2000-345 Santarém, Portugal.