1. Assistant Professor, Dept. of Civil and Environmental Engineering, The Pennsylvania State Univ., 215B Sackett Building, University Park, PA 16802-1408.
2. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana–Champaign, 3230d NCEL, MC. 250, 205 N. Mathews Ave., Urbana, IL, 61801.