Modal identification and cable tension estimation of long span cable-stayed bridge based on ambient excitation
YE Xi-jun1, YAN Quan-sheng1, LI Jian2, WANG Wei-feng1, ZHU Tian-feng1, LIU Ming-hui1
1. School of Engineering and Transportation, South China University of Technology, Guangzhou 510641, China2. College of Environmental Engineering, University of Illinois at Urbana-Champaign, Champaign 61801, USA
Abstract：Abstract: For health monitoring of long span cable-stayed bridge, modal parameter and cable tension are the key parameters to assess the condition of the bridge. A finite element model of Yamen bridge was modeled, modal test and cable vibration test of the bridge was performed under ambient excitation; A improved multiple reference DOFs stabilization diagram algorithm based on ERA was presented. By setting different reference DOFs in each group of data, NExT-ERA was used to identify modal parameters. Damping ratio, Consistent Mode Indicator from Observability (CMI_O) and Modal Assurance Criterion (MAC) was used as threshold to identify the most accuracy modal parameters. Lower order frequencies was estimated by quadratic fit method, and cable tension was estimated by two different methods. Based on the analysis of deck and cable vibration, it is evident that the vertical vibration of the bridge deck is tightly coupled with the cable vibrations within the frequency range of 0~3Hz.
2012, Vol. 31 
