Haili Liao

Weighting ensemble least-square method for flutter derivatives of bridge decks

Abstract In this paper, a reliable but simple identification method, here called the weighting ensemble least-square method (WELS), has been developed to extract all eight flutter derivatives of bridge deck from free vibration records. For every wind speed, free vibration test of section model is generally repeated several times in order to obtain more reliable parameter estimates. In the WELS method, many free vibration records at the same wind speed are regarded as an ensemble. The common mode parameters are then identified simultaneously from the ensemble data. The parameter fit is obtained by a nonlinear least-square method. Weighting factors are proposed to make each experiment record with the same weight in total residual error analysis. The ensemble composed of many records can reduce the effect of the colored noise of few records on the convergence of least-square iteration process. The flutter derivatives of two section models are identified to indicate the reliability and effectiveness of the WELS method.

VORTEX-INDUCED VIBRATION OF CONTINUOUS BEAM BRIDGE AND ITS MITIGATION

Because of higher stiffness, continuous steel beam bridges are usually free of flutter but are apt to vortex-induced vibration (VIV) due to low damping. Although vortex-induced vibration is a kind of limited amplitude response, and may occur at low wind speed. It may bring discomfort and fatigue, even endanger the bridge. In this paper, based on the large scale aeroelastic model wind tunnel testing, vortex-induced vibration of a continuous steel beam bridge was studied under uniform oncoming flow. In order to mitigate excessive amplitude of vortex-induced vibration, a kind of guide vane installed at both sides of the banister is investigated. The wind tunnel test also examines the role of additional damping in mitigating vortex-induced vibration.

Investigation of Influence Factors on Drag Coefficients for Stay Cables

INVESTIGATION OF INFLUENCE FACTORS ON DRAG COEFFICIENTS FOR STAY CABLES Zhiguo Li , Mingshui Li, Jiadong Zeng Haili Liao 1 Lecturer, School of Civil Engineering, Southwest Jiaotong University,Chengdu,China, lizhiguo@swjtu.cn 2 Professor, School of Civil Engineering, Southwest Jiaotong University,Chengdu,China, lms_rcwe@1 .com PhD Student, School of Civil Engineering, Southwest Jiaotong University,Chengdu,China, zjd_rcwe@163.com Professor, School of Civil Engineering, Southwest Jiaotong University,Chengdu,China, hlliao@swjtu.cn