1. Research Associate, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, UCB 428, Boulder, CO 80309.
2. Assistant Professor and Barry Faculty Fellow, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, UCB 428, Boulder, CO 80309 (corresponding author).
3. Emeritus Professor, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Colorado, UCB 428, Boulder, CO 80309.