1. Postdoctoral Associate, Dept. of Civil and Environmental Engineering, Univ. of Connecticut, 261 Glenbrook Rd., Storrs, CT 06269-2037 (corresponding author).
2. Northeast Utilities Foundation Chair Professor, Dept. of Civil and Environmental Engineering, Univ. of Connecticut, 261 Glenbrook Rd., Storrs, CT 06269-2037.