1. Graduate Student, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136.
2. Associate Professor, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136.
3. Assistant Professor, Dept. of Environmental Urban Engineering, Osaka City Univ., Osaka 558-8585, Japan; formerly, Visiting Lecturer, Dept. of Civil Engineering, Texas A&M Univ., College Station, TX 77843-3136.