1. School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University Xi’an, Shaanxi 710072, P. R. China
2. MIIT Key Laboratory of Dynamics and Control of Complex Systems, Northwestern Polytechnical University Xi’an, Shanxi 710072, P. R. China
3. School of Civil Engineering and Architecture, Xi’an University of Technology, Xi’an Shaanxi 710048, P. R. China