1. College of Civil Engineering, Huaqiao University, 361021 Xiamen, P. R. China
2. Key Laboratory for Intelligent Infrastructure and Monitoring of Fujian Province, Huaqiao University, Jimei Avenue 668, Xiamen, Fujian 361021, P. R. China
3. Department of Mechanical Engineering, School of Engineering, University of California, Merced, CA 95343, USA