1. Senior Engineer, SC Solutions, Inc., 1261 Oakmead Pkwy., Sunnyvale, CA 94085; formerly, Scientific Research Assistant, Dept. of Mechanical and Civil Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125.
2. Assistant Professor, Faculty of Engineering and Applied Sciences, Univ. of Los Andes, Alvaro del Portillo 12455, Las Condes, Santiago, Chile.
3. Professor, Dept. of Structural Engineering, Univ. of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (corresponding author).
4. Professor, Dept. of Mechanical and Aerospace Engineering, Univ. of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093.