1. Laboratory of Mechanics of Contacts and Structures, University of Lyon, CNRS, F-69621 Villeurbanne France
2. Laboratory of Mechanics of Contacts and Civil Engineering, University of Montpellier II, CNRS, F-34096 Montpellier France e-mail:
3. Laboratory of Mechanics of Contacts and Structures, University of Lyon, CNRS, F-69621 Villeurbanne France e-mail: