1. Associate Professor, Institute of Structural Engineering, Zhejiang Univ., Hangzhou 310058, P.R. China; formerly, Postdoctoral Fellow, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado Boulder, Boulder, CO 80309 (corresponding author).
2. Professor, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado Boulder, Boulder, CO 80309.
3. Professor, Institute of Structural Engineering, Zhejiang Univ., Hangzhou 310058, P.R. China.