1. Postdoctoral Fellow, Univ. of Waterloo, Dept. of Civil and Environmental Engineering, 200 Univ. Ave. W., Waterloo, ON N2L 3G1, Canada (corresponding author).
2. Professor, Univ. of Waterloo, Dept. of Civil and Environmental Engineering, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.
3. Norman W. McLeod Engineering Professor and Distinguished Professor Emeritus, Univ. of Waterloo, Dept. of Civil and Environmental Engineering, 200 University Ave. W., Waterloo, ON N2L 3G1, Canada.