Study On Wind-induced Response Characteristics Of Long-span Pipeline Suspension Bridges In Minjiang River

Pipeline suspension bridge is one of the most important structures in long-distance oil and gas transportation.However,for large span pipeline suspension bridge,because of its span is large while width is narrow,whole weight is light,fundamental frequency is low,structural rigidity is small,which cause it to be more sensitive under pulsating wind loads.In all seasons,the basic non-stop pulsating wind loads easily lead to the fatigue failure of pipeline suspension bridge,the light caused significant economic losses,if not resulted in casualties,environmental damage,bring bad social impact.Based on the research of relevant background literature,engineering parameter analysis and engineering field investigation,this paper has established the 3D model of the Yangbi River pipeline suspension bridge and the spatial wind load model of the engineering location,and carried on the research work about its nonlinear statics,static wind stability and wind-induced buffeting response dynamics.It masters the change rule of the structure wind load,its static stability,the influence of different factors on the static stability of the pipeline suspension bridge,the buffeting response characteristics of the different cables is subject to wind,and provides not only guidance advice of the later maintenance for the Yangbi River pipeline suspension bridge,but also theoretical support for the rest of the similar engineering design.The specific research work is as follows:First of all,through the analysis of the mechanical structure problems existing in the construction of the suspension bridge,realizes the necessity and importance of the wind-induced response in the design and maintenance of pipeline suspension.Based on the study of the wind-induced response of the pipeline bridge at home and abroad,puts forward the research direction of this paper:based on the 3D static wind instability model and the Davenport quasi-constant aerodynamic model,through Midas Civil,studies on the static stability and the wind-induced buffeting response of Yangbi River pipeline suspension bridge.Secondly,based on the cross-engineering parameters and structural geometrical nonlinearity,establishes the standard 3D model of pipeline suspension bridge by Newton-Raphson method,which lays model foundation for the follow-up analysis of wind response.And analyzes the influence of setting up anti-wind cable system on the natural dynamic characteristics of the pipeline suspension bridge,masters its vibration period,natural frequency and modal shape,and confirms the importance of setting up the wind cable system to improve the structural rigidity of the suspension bridge.At the same time,using the M.Shinozuka method,the local pulsating wind load of Yangbi River pipeline crossing is digitized and converted into an applicable wind speed time function by Matlab programming,and further obtains the local natural wind load time function,as a wind load model for wind-induced chattering time domain analysis.Thirdly,based on the 3D static wind instability theroy,studies on the Yangbi River pipeline suspension bridge static wind torsion instability speed,the impact of the wind angle change,the cable system is subject to wind,and whether to set up the wind cable system for structural stability by internal and external incremental double iterative method.The results show that the static wind torsion instability limit wind speed of the suspension bridge is 123.2m/s,which does not exceed the extreme wind speed of the local 100 years(38.7m/s);with the increase of the wind angle,the static wind instability wind speed of the pipeline suspension bridge decreases,and its static wind stability also decreases;the cable system to bear a larger proportion of the load,the impact for the stability of the pipeline suspension bridge can’t be ignored;the setting of the wind cable system has a significant effect on the wind response of the structure,which can significantly improve the overall stiffness of the structure and enhance the wind resistance of the structure.Finally,based on the Yangbi River crossing engineering,studies on the influence of structural dynamic response when different cable of pipeline suspension bridge being subject to wind.The results show that,for the stiffening beam,the main cable,and the wind cable of the structural components,considering the cable is subject to wind more and more responsive,indicating that the impact of pipeline suspension bridge buffeting response when cable system is subject to wind is much bigger,we should take more consideration about it in the later engineering design,especially for the main cable and wind cable is subject to wind analysis.The vibration intensity and vibration amplitude of the wind cable is higher than that of the stiffening beam and the main cable,which is more sensitive to the wind load under the natural wind load.The stiffening beam and the towers appear to have localized stress concentration and beyond their stress allowable range,and the maximum stress of the wind cable is very close to its allowable stress,indicating that the entire suspension bridge may appear security issues due to local unit failure in the local 100 years wind.