1. a Ecole Centrale de Lyon , 36 avenue Guy de Collongue, 69134 Ecully Cedex, France Phone: Fax: E-mail:
2. b University of Nottingham, School of Civil Engineering , Nottingham, NG7 2RD, UK Phone: Fax: E-mail:
3. c University of Nottingham, School of Mechanical, Materials and Manufacturing Engineering , Nottingham, NG7 2RD, UK