1. Ph.D. Student, Dept. of Civil Engineering, McMaster Univ., 1280 Main St. W., Hamilton, ON, Canada L8S 4L7 (corresponding author).
2. Professor, Dept. of Civil Engineering, Univ. of Toronto, Ontario, 35 St. George St., Toronto, ON, Canada M5S 1A4.
3. Professor, Dept. of Civil Engineering, McMaster Univ., 1280 Main St. W., Hamilton, ON, Canada L8S 4L7.