You-liang Ding

Temperature Effects on Strain Influence Lines and Dynamic Load Factors in a Steel-Truss Arch Railway Bridge Using Adaptive FIR Filtering

AbstractThe dynamic strain response due to the passing trains is one of the most important indexes in the design and maintenance of long-span steel-truss arch railway bridges. The strain influence ...

Detection and Location of the Degraded Bearings Based on Monitoring the Longitudinal Expansion Performance of the Main Girder of the Dashengguan Yangtze Bridge

AbstractTemperature field data from the steel truss arch girder and longitudinal displacement data from six groups of rubber bearings were collected by the structural health monitoring system for the Dashengguan Yangtze Bridge. By using long-term monitoring data, two correlations are investigated: the linear correlation between the longitudinal displacement and the temperature field (including uniform temperature and temperature gradient); and the linear correlation of the longitudinal displacements in different locations. A multivariate linear regression equation is used to model the first correlation, and a Lagrange polynomial interpolation is used to model the second correlation. The final mathematical models, representing the healthy state of the bearings, can be applied to simulate the longitudinal displacements of the main girder. Furthermore, the change regularity of longitudinal displacements for the degraded rubber bearings is revealed taking advantage of a hysteretic model and presumed envelope ...

Full-Range S-N Fatigue-Life Evaluation Method for Welded Bridge Structures Considering Hot-Spot and Welding Residual Stress

AbstractFatigue cracking is crucial issue for welded steel bridges that endure repeated vehicle loads. With typical fatigue-life evaluation methods, it is difficult to consider the influence of low stress amplitude. Based on existing full-range S-N curves and their formulas for base metal, a unified fatigue-life evaluation method is recommended for welded joints. The basis for construction of full-range S-N curves is to obtain the welding residual stress and stress concentration factor. In this paper, rib-to-deck welded joints are introduced as examples to demonstrate the detailed steps of a fatigue-life evaluation procedure. From the analysis of welding residual stress, it can be concluded that residual stress is influenced by the geometric dimensions of the composite members. With an increase in the geometric dimensions, the level of residual stress is increased. In addition, static-load experiments were conducted to obtain the stress concentration factor. A hot-spot full-range S-N curve was then obtain...

Detection and Localization of Degraded Truss Members in a Steel Arch Bridge Based on Correlation between Strain and Temperature

AbstractTaking advantage of the structural health monitoring system installed on the steel truss arch girder of the Dashengguan Yangtze Bridge, the monitoring correlation between strain and uniform...

Finite Element Modeling of the Tower of Runyang Cable-stayed Bridge Based on Ambient Vibration Test

In this paper, the multi level model updating method is put forward for finite element (FE) modeling of the bridge tower for long-span cable-stayed bridge, which includes model order updating, model structure updating, and model parameter updating. According to the design drawings of the tower of the Runyang Cable-stayed Bridge, the element numbers of the tower and calculation parameters for nodal rigid zone are both determined based on the analysis results of model order error and the structural modeling error. The FE model of the tower is further dynamically updated according to ambient vibration test through modal sensitivity based model updating method. Model updating verification results reveal that the model parameter updating should take nodal rigid zone and parameter modification restriction into account, on the basis of which the updated tower FE model can properly reflect the dynamic characteristics of the tower and can serve the baseline FE model for the purpose of structural health monitoring and safety evaluation.

Dynamic Performance Evaluation of a High-Speed Four-Track Railway Bridge Traversed by Multiple Trains

AbstractWith the continuous construction of high-speed railway networks in China, long-span railway bridges which carry multiple tracks are being put into service on the high-speed railway line. Ho...

Early Warning of Abnormal Train-Induced Vibrations for a Steel-Truss Arch Railway Bridge: Case Study

Considering the new challenges for high-speed railway bridges, the early warning of abnormal train-induced vibrations is necessary for ensuring the operation safety of both the bridge structures and the trains on the bridge. In this study, an online monitoring system for detecting abnormal train-induced vibration responses is developed, and the Dashengguan Yangtze River Bridge is used for illustration. First, to accurately investigate the influence of different train lanes and the number of carriages on train-induced vibrations, the speed-acceleration (train speed-bridge acceleration) correlations under different loading cases are obtained using an online identification method. Then, a twostage method for early warning of abnormal train-induced acceleration responses of the bridges is developed using wavelet packet decomposition and interval estimation theory. Finally, the early warning method for identifying abnormal train-induced transverse vibrations is presented. The results show that (1) the train lane and the number of carriages affect the speed-acceleration correlations, and the identification of loading cases is needed for the accurate monitoring of speed-acceleration correlations; (2) by using wavelet packet decomposition, the median line of speed-acceleration correlations can be optimally extracted, and the early warning thresholds for abnormal train-induced acceleration responses can be properly determined using the interval estimation theory compared with the point estimation theory; and (3) the train running parameters of the Dashengguan Yangtze River Bridge are all within safe limits, but the wheel unloading rate and derailment coefficient have reached 60% of the limits due to the train-induced transverse vibrations. The effects of train-induced transverse vibration on the train running stability is worthy of attention.DOI: 10.1061/(ASCE)BE.1943-5592.0001143.© 2017 American Society of Civil Engineers. Author keywords: Structural health monitoring; Steel-truss arch railway bridge; Train-induced vibration; Early warning threshold; Train running parameter.

Structural behavior analysis of a continuous steel truss arch railway bridge integrating monitoring data

Using theoretical modeling combined with monitoring data, the typical dynamic and static behaviors of a continuous steel truss arch railway bridge are evaluated. The dynamic behavior involves an impact factor induced by the action of running trains, and the static behavior refers to axial bending performance and the stress distribution among different planes of the truss. The transverse position, length, and speed of running trains are introduced to conduct an analysis of their influences on the dynamic and static behaviors of the bridge superstructure. A structural safety evaluation is also conducted by comparison with the provisions recommended by design codes and by analysis of absolute stress. It is concluded that three types of members present different dynamic behaviors and that the value of the impact factor for chords B exceeds the provision recommended by the design codes. Chords C present the greatest ratio of bending stress versus axial stress. An imbalance of stress distribution exists among the three planes of the truss, and the difference is the smallest when trains run along the middle railways. Because the train-induced stress is considerably lower, the dynamic and static performances of the bridge are within the scope of safety.