1. Researcher, IFSTTAR, Bridges and Structures Dept., Safety and Durability of Structures, 58 boulevard Lefebvre, F-75732 Paris Cedex 15, France.
2. Professor and the Fazlur R. Kahn Endowed Chair of Structural Engineering and Architecture, Dept. of Civil and Environmental Engineering, ATLSS Engineering Research Center, Lehigh Univ., 117 ATLSS Dr., Bethlehem, PA 18015-4729 (corresponding author).