1. Read Jones Christoffersen, Suite 500, 1816 Crowchild Trail NW, Calgary, AB T2M 3Y7, Canada.
2. Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB T6G 2W2, Canada.
3. SPECO Engineering, Ltd., 43 Schiller Crescent NW, Calgary, AB T3L 1W7, Canada.