Study On Reasonable Construction State Of Main Cable Shape Of Long-Span Asymmetric Suspension Bridge

With the continuous improvement of the level of bridge construction in China,the span of the suspension bridge built is getting larger and larger,and the geometric nonlinearity of the main cable of the suspension bridge is more intense.In this paper,the side-span asymmetric suspension bridge-Xijiang Bridge is under construction,and the main cable shape is the research focus.The previous research results are summarized.The FORTRAN program is compiled according to the segmented catenary iterative algorithm to calculate the main cable in the bridge state.Parameters such as linear and unstressed length,and then use these parameters to establish a full bridge model with MIDAS and accurately solve the bridge equilibrium state to ensure the safety of the suspension bridge during construction and operation.Based on the model,the bridge-line shape,the air cable shape and the unstressed length of the main cable are analyzed in detail under the reasonable condition of the suspension bridge.The important parameters of the suspension bridge during the actual construction process are analyzed and the variation law is studied.These conclusions can provide reference and reference for the design and construction of this type of bridge,and provide an effective basis for the monitoring of the suspension bridge construction process.The main research contents and results of this paper are:(1)The development history of suspension bridges is briefly described,and the characteristics of modern suspension bridge construction are summarized.The development process of suspension bridge calculation theory is introduced,and its theoretical content,advantages and disadvantages are discussed.The research status of main cable linear calculation theory of suspension bridges at home and abroad is emphasized.An overview was made.(2)The theory of analytic method for calculating the main cable shape of suspension bridge is introduced.Based on the theory of segmented catenary,the parameters of main cable shape and stress-free length of suspension bridge bridge state are solved by Visual Fortran programming.Explain the steps of MIDAS/Civil to build a model through the suspension bridge modeling assistant.Analyze and contrast the pure analytical method and the MIDAS suspension bridge modeling assistant in the calculation process of the suspension bridge.The method of accurately solving the reasonable bridge state of the asymmetric suspension bridge is proposed.The calculation accuracy of the method is verified by taking the supporting project as an example.(3)Unloaded cable shape is the key link in the construction of the suspension bridge.The accuracy of the calculation is crucial to ensure that the bridge line shape meets the design requirements.Taking the calculation of the unloaded cable shape of the side span asymmetric suspension bridge as an example,the effects of temperature variation,span variation and main tower pre-lift on the unloaded cable shape are analyzed,and a reasonable unloaded cable shape is determined on this basis.(4)In order to improve the precision of construction control of asymmetric suspension bridge,this paper studies the control principle and method of main cable erection,main cable saddle thrust and limit sling tension,and compares with the measured data.Corresponding conclusions and recommendations.