1. Department of Civil and Environmental Engineering; The University of California; Berkeley 94720 CA U.S.A.
2. Department of Engineering Structure and Mechanics; Wuhan University of Technology; Wuhan 430070 China
3. Livermore Software Technology Corporation; 7374 Las Positas Road Livermore 94551 CA U.S.A.
4. Department of Civil, Environmental, and Architectural Engineering; University of Colorado Boulder; Boulder 80309 CO U.S.A.