1. Graduate Research Assistant, N107 Engineering Building 1, Dept. of Civil and Environmental Engineering, Univ. of Houston, Houston, TX 77204-4003.
2. Professor, N127 Engineering Building 1, Dept. of Civil and Environmental Engineering, Univ. of Houston, Houston, TX 77204-4003.
3. Assistant Professor, N134 Engineering Building 1, Dept. of Civil and Environmental Engineering, Univ. of Houston, Houston, TX 77204-4003 (corresponding author).