1. Professor, Dept. of Civil and Environmental Engineering, Univ. of Massachusetts, Amherst, MA 01003 (corresponding author).
2. Professor, Research Institute in Civil and Mechanical Engineering, UMR CNRS 6183, Ecole Centrale Nantes, BP 92101, 44321 Nantes, France.
3. Visiting Researcher, Univ. of Massachusetts, Amherst, MA 01003.
4. Research Assistant, Research Institute in Civil and Mechanical Engineering, UMR CNRS 6183, Ecole Centrale Nantes, BP 92101, 44321 Nantes, France.