1. Assistant Professor, Construction Engineering and Management Division, Charles Durham School of Architectural Engineering and Construction, Univ. of Nebraska-Lincoln, 113 Nebraska Hall, Lincoln, NE 68588 (corresponding author).
2. Assistant Professor, Dept. of Civil and Environmental Engineering, Univ. of Michigan, 2350 Hayward St., Room 2340 G.G. Brown Building, Ann Arbor, MI 48109.
3. Edwin Howard Armstrong Professor of Civil Engineering and Engineering Mechanics and Professor of Earth and Environmental Engineering and of Computer Science, Columbia Univ., City of New York, 510 Southwest Mudd Building, 500 West 120th St., New York, NY 10027.