Dynamic analysis of long-span cable-stayed bridges under wind and traffic using aerodynamic coefficients considering aerodynamic interference

Wang S., Wan X., Guo M., Qiao H.

Li G., Han W., Zhang Y., Weng G.

Suspenders are critical force transmission components of a suspension bridge and may be more prone to fatigue damage due to environmental aggression and repetitive live loads. To evaluate the safety of the suspender more accurately, a fatigue life evaluation framework of the rope suspender was proposed, where a time-varying fretting-corrosion-fatigue degradation process of the rope wire and probabilistic critical limit states based on failure area were integrated. A case study on the rope suspenders of a prototype suspension bridge was performed under the random vehicle and wind loads, and the reliability indices and fatigue life of the rope suspender were obtained. Results show that the fretting wear had an obvious effect on the degradation process of the wire rope in conjunction with corrosion fatigue, and the fatigue life of the rope suspender would be less than its design life. The proposed method can comprehensively evaluate the service life of wire rope suspenders and provide replacement suggestions more timely, ensuring the safety of the bridge operation.

Wu J., Cai C., Li X., Liu D.

The dynamic performance and safety of both the train and the bridge are great concerns for long-span bridges subjected to crosswinds. For railway bridges, there is track laid on the bridge deck. The wind, train, track, and bridge subsystems form a complicated coupling system. This paper presents the dynamic responses of both the train and the bridge under crosswinds based on a wind-train-track-bridge coupled model, in which the vibration effect of the track structure involved in the coupling system is especially considered. For studying the dynamic responses of both the train and the bridge, models of railway vehicle dynamics are used for the train and a three-dimensional finite element model is used for the bridge. The train-track interaction and the track-bridge interaction are respectively considered. The wind action on the train and the bridge consists of a steady-state force and an unsteady-state force. Based on an in-situ test, the proposed numerical wind-train-track-bridge model involving the vibration effect of the track is validated. Then, the application of this proposed model on a long-span cable-stayed bridge on the Shanghai-Suzhou-Nantong HSR (high-speed railway) is presented as a case study. The typical running train and track currently serving in the Chinese railway transportation system are modeled in this study. Excitations from track irregularities are also taken into account. Finally, with the proposed wind-train-track-bridge coupled model, the dynamic performance of both the train and the bridge subjected to crosswinds are investigated.

Han W., Liu X., Guo X., Chen S., Yang G., Liu H.

To promote and develop the theoretical basis and application of the wind-vehicle-bridge coupling vibration system, the corresponding research status and prospects are reviewed and discussed from five aspects, i.e., the analytical framework, the aerodynamic interference, the evaluation criteria, the design loads of long-span bridge and the double-deck rail-cum-road bridge. The refining process of analysis system is reviewed from the aspects of simulation wind load, vehicle load and bridge structure, and the corresponding coupling relationship. For aerodynamic interference, the development process is summarized from the simulative precision of the elements (wind, vehicle and bridge), the load cases and the object of interference. For evaluation criteria, the corresponding development course is summarized from the certain evaluation method to uncertain one. For long-span bridge design load, the wind and vehicle loads are reviewed and summarized from current multinational codes and theoretical research. For double-deck rail-cum-road bridge, the mechanism of multi-element coupling relationship and corresponding aerodynamic interference are both reviewed. By comprehensive review and summary, the analytical framework is in the process from simplification to refinement. The simulation and consideration of the objects of structural interference gradually become complex. The corresponding simulation theory, wind tunnel scale, test equipment and technology are the key factors to limit its development. For systematic evaluation of vehicle and bridge, the structural and systemic security are the basis of the evaluation, and the auxiliary components and functional evaluation need to be paid more attention. The evaluation criterion will be developed from certain method to reliability assessment. For design load of long-span bridge, the vehicle load is gradually transferred from the simple application of the design load of small-medium span bridge into a complex model considering the load characteristics. For double-deck rail-cum-road bridge, the basic theory and experimental study on coupling mechanism and aerodynamic interference need to be developed.

Gao W., Li G., Su Q., Han W.

The presence of rigid central clamps (RCCs) minimises the damage potential of short suspenders and expansion joints in in-service long-span suspension bridges. The study presented in this paper eva...

Ge C., Chen A.

AbstractThe Sutong Bridge with a span of 1088 m is supported by 272 cables, whose lengths range from 152.85 m to 576.77 m (the longest in the world). The half-year vibration acceleration data of tw...

Yin X., Song G., Liu Y.

Dynamic responses of highway bridges induced by wind and stochastic traffic loads usually exceed anticipated values, and tuned mass dampers (TMDs) have been extensively applied to suppress dynamic responses of bridge structures. In this study, a new type of TMD system named pounding tuned mass damper (PTMD) was designed with a combination of a tuned mass and a viscoelastic layer covered delimiter for impact energy dissipation. Comprehensive numerical simulations of the wind/traffic/bridge coupled system with multiple PTMDs (MPTMDs) were performed. The coupled equations were established by combining the equations of motion of both the bridge and vehicles in traffic. For the purpose of comparing the suppressing effectiveness, the parameter study of the different numbers and locations, mass ratio, and pounding stiffness of MPTMDs were studied. The simulations showed that the number of MPTMDs and mass ratio are both significant in suppressing the wind/traffic/bridge coupled vibration; however, the pounding stiffness is not sensitive in suppressing the bridge vibration.

dos Santos R.C., Larocca A.P., de Araújo Neto J.O., Barbosa A.C., Oliveira J.V.

This article proposes a contribution to the inspection procedures of curved reinforced concrete road bridges through a short-term monitoring plan using topographic techniques during an ambient vibration test (AVT) under normal traffic conditions. The proposed monitoring method was used to determine the 3D displacements in the observed points, which enabled the evaluation of vibrations of two points on the bridge deck in the vertical (Z), horizontal (Y)—perpendicular to track direction—and longitudinal (X) directions of the track. The application consisted of measurements performed under normal traffic conditions with two RTSs with a nominal sampling rate of 10 Hz. The targets were two prisms located on opposite edges of the runway and perpendicular to the traffic direction. A tri-dimensional view of the residuals from the measured coordinates and Morlet continuous wavelet transform (CWT) are used to establish the time and frequency-domain of the bridge vibrations and analyze the behavior and movement of the midspan in an AVT. This study confirms the feasibility of using high sampling rate RTSs for monitoring dynamic responses of small concrete bridges without interrupting traffic on highways.

Dong F., Cheng J.

An inverse reliability-based approach is proposed to estimate the aerostatic stability safety factors of long-span cable-stayed bridges in order that their reliability against the failure mode of aerostatic stability meets a desired level of safety. For the purpose of estimation, uncertainties associated with the basic wind speed at the bridge deck location, critical aerostatic stability velocity, the wind conversion factor from a scaled model to the prototype structure and the gust speed factor are taken into account. The proposed approach combines concepts from the inverse reliability method and the calculation method of the critical aerostatic stability velocity of long-span cable-stayed bridges. A procedure of the proposed approach for the estimation of aerostatic stability safety factor, which at the same time achieves a target reliability, is outlined. This proposed approach is illustrated using three existing long-span cable-stayed bridges. The results indicate that the proposed approach provides validity information concerning the improved accuracy of the estimation of aerostatic stability of long-span cable-stayed bridges over the traditional method. Additionally, the effects of various parameters on the aerostatic stability safety factor of long-span cable-stayed bridges are analysed and discussed.

Yang D., Yi T., Li H., Zhang Y.

Wind action is one of the environmental actions which has substantial static and dynamic effects on the long-span bridges. The main objective of the paper is to reveal the static and dynamic characteristics of the regular wind and typhoon condition. A monitoring-based investigation has been carried out to analyze the characteristics of the wind actions. The static characteristics of regular wind and typhoon condition are investigated by analyzing the average wind speed. Moreover, the dynamic characteristics of the two conditions of wind actions are studied by analyzing the parameters of turbulence intensity and gust factors. The correlation analysis is performed between the lateral wind speed and the lateral girder displacement to reveal the static effects of the wind actions on the bridge structures. It is concluded that static and dynamic characteristics of regular wind and typhoon conditions are quite different, and the dynamic effects of wind actions obtained based on monitoring data need to be further studied.