1. Professor, Div. of Civil Engineering, Aeronautics Institute of Technology, São José dos Campos, SP 12.228-900, Brazil (corresponding author).
2. Professor, Dept. of Civil and Environmental Engineering, Colorado State Univ., 1372 Campus Delivery, Fort Collins, CO 80523-1372.
3. Associate Professor, Div. of Environmental Science and Engineering, Colorado School of Mines, Coolbaugh Hall, Golden, CO 80401-1887.