1. a Department of Civil Engineering , Chongqing University , Chongqing , 400045 , P. R. China
2. b Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing University, Ministry of Education , Chongqing , 400045 , P. R. China
3. c Chongqing Vocational College Of Architecture Engineering , Chongqing , 400039 , P. R. China