1. Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803-6405; cegzv1@lsu.edu
2. Department of Aeronautics and Astronautics, Air Force Institute of Technology, 2950 P Street, Wright-Patterson Air Force Base OH 45433-7765; Anthony.Palazotto@afit.edu
3. Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University , 1400 Townsend Drive, Houghton MI 49931-1295; xgao@mtu.edu