1. Graduate Student, Dept. of Civil, Architectural and Environmental Engineering, Univ. of Texas at Austin, 301 E Dean Keeton St. Stop C1752, Austin, TX 78712-1094.
2. Associate Professor, Dept. of Civil, Architectural and Environmental Engineering, Univ. of Texas at Austin, 301 E Dean Keeton St. Stop C1752, Austin, TX 78712-1094 (corresponding author).