1. College of Civil Engineering, Nanjing Tech University, Nanjing, P. R. China
2. Shangqiu University, Shangqiu, P. R. China
3. Department of High-speed Transportation Management, Shanghai Urban Investment Ring Expressway Construction and Development Co., Ltd, Shanghai, P. R. China
4. Department of Civil Engineering, Shanghai Jiao Tong University, Shanghai, P.R. China