1. Professor and Holder of the Spencer J. Buchanan Chair, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77834-3136. E-mail: briaud@tamu.edu
2. Professor, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77834-3136.
3. Graduate Student, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77834-3136.