1. School of Civil Engineering, Chongqing University, Chongqing, P. R. China
2. Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing, P. R. China
3. Department of Civil Engineering, University of British Columbia, Vancouver, Canada
4. School of Civil Engineering, Harbin Institute of Technology, Harbin, P. R. China