| With the socio-economic development,in order to make the economy more efficient,sometimes it is urgent to cross rivers or canyons,more and more large span steel truss girder cable-stayed bridges appear,with train load and wind load as the main excitation source,and due to the large span,the additional deformation produced by the bridge under the action of live train load,temperature action,wind load,earthquake,long-term creep,etc.cannot be ignored.The thesis examines the impact of extra deformation on the bridge’s dynamic response,as well as the dynamic response of the wind-vehicle-bridge system when such deformations are taken into account by using model updating technique.It calculates these effects and analyzes the bridge’s structural stability and the safety of train traffic,using a large-span steel truss cable-stayed bridge designed for public-rail transportation as the engineering foundation.The principal findings and deductions are as follows:(1)According to the features of natural wind field,the average wind and pulsating wind in the bridge site area were characterized by combining the measured data from the health monitoring system on the bridge;The wind field that pulsates in the area around the bridge site was simulated using the harmonic synthesis method through numerical computation.(2)In order to analyze the vibration characteristics of the structure,a finite element model was developed using the bridge design drawings.The model was simplified as necessary.Furthermore,a multi-degree of freedom vehicle model was created,based on the CRH3 rolling stock;The wind load model is established according to Davenport quasi-steady theory.Combined with the bridge,train and wind load model,the system that couples the wind,vehicle,and bridge has been established by displacement coupling method in ANSYS.(3)The bridge model is updated according to the additional vertical deformation of the bridge generated by temperature and the additional lateral deformation of the bridge generated by side wind,and the dynamic analysis of the bridge coupling was conducted using the revised bridge model to investigate how the bridge’s increased deformation affects its dynamic response.Only the lateral wind effect produces the lateral additional deformation to make the bridge span transverse displacement and the train axle transverse force has a large increase;the impact of wind loads intensifies the already existing deformation in the dynamic response of the bridge,while the additional deformation caused by the bridge’s exposure to side winds and temperature changes leads to an increase in the bridge’s dynamic response;it is necessary to consider the influence of the additional deformation in the wind-vehicle-bridge coupling calculation.(4)The link between the wind,train,and bridge is examined by studying the dynamic response using a comprehensive analysis that considers the bridge’s additional deformation and track irregularities.The study explores various wind and train speeds,delving into the dynamic response of both the train and bridge.The results indicate that the lateral direction experiences a more pronounced dynamic response in both the bridge and train under the wind load compared to the vertical direction;the resonance of the bridge may occur when the train crosses the bridge;the lateral stiffness of the bridge cannot meet the normal operation of the structure and the safe passage of the train when the wind speed reaches 40 m/s;The impact of a change in vehicle speed on the dynamic response of both the train and bridge is not as evident as that caused by a change in wind speed.When the wind speed exceeds 20 m/s,the wind plays a dominant role in the influence on the bridge stability and train safety and comfort;when the wind speed reaches 30 m/s,it will cause the wheel weight reduction rate and the lateral acceleration of the train to exceed the limit value,and it is recommended to suspend the train operation. |
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