1. Dept. of Civil Eng., Univ. of Nebraska-Lincoln, 205C PKI, 1110 S. 67th St., Omaha, NE 68182; and, Affiliate Faculty, State Key Lab of Water Resources and Hydropower Eng. Sci., Wuhan Univ., Hubei 430072, PRC.
2. Professor, Engineering Research Center, Dept. of Civil Engineering, Colorado State Univ., Fort Collins, CO 80523. E-mail: pierre@engr.colostate.edu