Study On Static Stability Of Cable-satyed Pipe Bridge With Large Span Water Ransmission

In water resources transportation projects,water pipelines often cross rivers.As a new special structure in pipeline crossing projects,long-span cable-stayed pipeline bridges lay pressure water pipelines on bridge decks,and use pipelines to cross bridges.This economical and efficient way of water diversion and water diversion is increasingly used in long-distance water distribution projects.At the same time,the structural stress of the long-span cable-stayed pipeline bridge during the construction and operation stages is very complex.The water hammer effect and pipeline vibration generated in the pipeline during the operation of the water conveyance system can not be ignored.The influence of the cable-stayed pipe bridge system,the seismic load has a significant impact on the cable-stayed pipe bridge structural system.In this paper,the finite element calculation model of the cable-stayed pipe bridge is established based on the research background of the cable-stayed pipe bridge crossing structure in a long-distance water conveyance project.Firstly,the nonlinear static behavior and structural stability of the cablestayed pipe bridge in the bridge operation stage are studied.Secondly,the dynamic response of the cable-stayed pipe bridge structure under the water hammer impact effect is discussed in detail.Finally,the influence of uniform excitation and multi-point non-uniform excitation on the cablestayed pipe bridge structure is studied respectively.The main research contents and corresponding conclusions are as follows:(1)Considering the geometric nonlinearity of the cable-stayed pipe bridge structure,the iterative optimization calculation of the cable force of the bridge is carried out to determine the reasonable bridge state.The stress state of the cable-stayed pipe bridge under the load combination in the operation stage of the bridge is analyzed,and the structural stability of the pipe bridge structure in the operation stage of the bridge is checked.The results show that the internal force of the stay cable in the completed bridge state conforms to the distribution of the cable force in the designed completed bridge state.The long cable force is large and the short cable force is small.Under the load combination in the completed bridge operation stage,the deformation and stress amplitude of the main components of the cable-stayed pipe bridge meet the calculation provisions of the relevant design specifications of the cable-stayed bridge,and the structural instability safety factor meets the requirements of the specification.(2)The dynamic characteristics of water-pipeline-cable-stayed bridge structure are systematically analyzed,and the resonance of water pipeline and cable-stayed bridge structure is reviewed.The dynamic response characteristics of the main components of the pipe bridge under the excitation load of water hammer are analyzed.The influence of different loading methods and different closing time of the valve on the displacement and stress of the components is studied.The results show that there is no possibility of resonance between the water pipeline and the cable-stayed bridge under the condition of no water and water in the pressure pipeline,and the pipeline vibration caused by the hydraulic vibration source will not cause the resonance of the pipe-bridge system.The non-uniform loading method of water hammer impact makes the dynamic response of the main components of the pipe bridge increase significantly compared with the results of uniform application,but it still does not cause the instability or failure of the components.(3)Three seismic waves are selected to comprehensively analyze the structural dynamic response of the cable-stayed pipe bridge under the uniform excitation of the earthquake.The largest response among the three seismic waves is selected as the structural dynamic response of the pipe bridge structure under the uniform excitation.The seismic wave with the largest response is selected for the longitudinal input of the cable-stayed pipe bridge,and the influence of the traveling wave effect on the seismic effect of the pipe bridge structure is analyzed.The structure shows that the dynamic response of the pipe bridge structure under the three-dimensional ground motion is relatively large,and the maximum structural displacement and internal force peak are obtained at the key position of the bridge tower,under the action of the traveling wave effect.The structural deformation and internal force peak of the tower and main girder of the bridge are reduced to varying degrees compared with the uniform excitation,which has a beneficial effect on the structural force,and increases with the increase of the apparent wave velocity,and finally approaches the dynamic response of the structure under the uniform excitation.However,the traveling wave effect will increase the vertical displacement of the main girder in the mid-span,which has an adverse effect on the structure,and needs to be paid attention to in the seismic design.