1. Assistant Professor, Dept. of Civil Engineering, Univ. of Nebraska-Lincoln, 2200 Vine St., 362P Whittier Research Center, Lincoln, NE 68583 (corresponding author).
2. Associate Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave. Urbana, IL 61801.
3. Professor and Chair, Dept. of Civil and Environmental Engineering, Northeastern Univ., 360 Huntington Ave., Boston, MA 02115.
4. Professor, Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana-Champaign, 205 N. Mathews Ave. Urbana, IL 61801.