1. University of Victoria, Department of Civil Engineering, Engineering and Computer Science (ECS) 304, Victoria, British Columbia V8W 2Y2, Canada
2. University of Malawi, The Polytechnic, 303, Blantyre 3, Malawi
3. ETH Zurich, Clausisstrasse 37, 8092 Zurich, Switzerland
4. Polytechnique Montreal, Department of Civil, Geological and Mining Engineering, P.O. Box 6079, Montreal, Quebec v, Canada