1. School of Civil Engineering, Guangzhou University, Guangzhou, Guangdong 510006, P. R. China
2. School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou, Guangdong 510006, P. R. China
3. Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan