1. Assistant Research Professor, Desert Research Institute, 755 East Flamingo Rd., Las Vegas, NV 89119 (corresponding author).
2. Associate Research Professor, Desert Research Institute, 755 East Flamingo Rd., Las Vegas, NV 89119.
3. Assistant Professor, Dept. of Civil Engineering, Univ. of New Mexico, MSC01 1070, Albuquerque, NM 87131.