1. Professor, Centre de Recherche, Université de Bretagne Sud, Institut de Recherche Dupuy de Lôme, Rue de Saint Maudé, BP 92116, 56321 Lorient Cedex, France (corresponding author).
2. Professor, School of Civil Engineering, Univ. of Queensland, St. Lucia, QLD 4072, Australia.
3. School of Civil Engineering, Univ. of Queensland, St. Lucia, QLD 4072, Australia.