1. Dept. of Civil, Architectural, and Environmental Engineering, Univ. of Texas at Austin, Austin, TX 78712-0273.
2. Professor, Dept. of Civil, Architectural, and Environmental Engineering, Univ. of Texas at Austin, Austin, TX 78712-0273 (corresponding author).
3. Professor, Dept. of Civil, Architectural, and Environmental Engineering, Univ. of Texas at Austin, Austin, TX 78712-0273.