Analysis Of Static And Dynamic Characteristics And Design Parameters Influence Of Single Tower Self-anchored Suspension Bridge

In this paper,a self-anchored suspension bridge in Guizhou Province is taken as the research object.By combining numerical simulation with construction monitoring data,the static and dynamic characteristics of the bridge and the influence of design parameters are studied as follows:(1)This paper briefly describes the structural characteristics and stress modes of self-anchored suspension bridges,summarizes the development and research status of self-anchored suspension bridges at home and abroad,affirms the development prospects and structural advantages of self-anchored suspension bridges in China,and introduces the background of the bridge.(2)The elastic theory,deflection theory and finite displacement and non-linear finite element theory commonly used in the analysis and calculation of early suspension bridges are introduced.Summarize the basic assumptions in the use of three computational theories.The errors of early calculation theory in calculation of long span and complex suspension bridges are analyzed.The accuracy and rigor of finite displacement and non-linear finite element theory in calculation of suspension bridges are affirmed.Finally,the non-linear influencing factors of self-anchored suspension bridges are briefly introduced.(3)According to the design data and site conditions,the complete finite element model of the bridge is established,and the main cable shape finding,parameter impact analysis,structural system transformation scheme research are carried out.The calculation of main cable shape finding shows that the traditional parabola method is simpler than the piecewise catenary method and the nonlinear finite element method,but the error is large.The results of the latter two methods are close and the precision is high.At the same time,it proves that the non-linear finite element software Madis/Civil has a high feasibility to control the construction of this project.When the influence of structural load information on main cable shape parameters is analyzed,the main cable shape finding is obviously affected by structural load information,which needs to be accurately counted.Before erecting the main cable strand,the factory parameters of the main cable strand should be sampled to ensure the accuracy of the parameters such as upsetting die of the main cable.Temperature is a highly sensitive factor.During the erection of the main cable strand,the range of temperature variation should be controlled and the erection scheme should be adjusted in real time according to the actual temperature.According to the structural characteristics,four systems conversion schemes are put forward and demonstrated.Finally,the optimum scheme is to install tensioned suspension cable symmetrically from the side to both sides of the main tower.The analysis results show that the scheme has high feasibility and safety factor,uniform force acting on the completed suspension rod and main cable,and small alignment error of the main cable and girder.(4)The finite element analysis of the bridge is carried out to determine the reasonable completedstate of the bridge.It is proved that the cable girder alignment and internal force of the cable under this state are accurate and accurate,and are suitable for the static and dynamic analysis work in the later stage.The influence of temperature,moving load and static wind load on the static behavior of the structure is analyzed.The results show that temperature has a great influence on the cable alignment,moving load has a great influence on the main span girder alignment,and static wind load has a little influence on the consolidated concrete structure of the tower girder.The rise-span ratio of main span and main cable has little influence on the static behavior of structure,while the elastic modulus of main cable and the shrinkage and creep of concrete have great influence on the structural stress.It is necessary to select reasonable design material parameters and strengthen the maintenance measures of concrete structure.The breakage of a single sling has little influence on the safety of the structure,and the whole structure will have adverse effects on the resistance,which proves that the structure has sufficient stiffness and strength.The natural vibration characteristics of the bridge are analyzed.The results show that the first-order natural frequency is0.816 Hz,the span is small,the tower and beam are consolidated,and the bridge has larger stiffness.The ground anchor type of the bridge has a slightly higher natural frequency and stiffness than the self-anchored type.Vertical vibration of girder and transverse vibration of main cable appear more frequently,and torsional mode is backward,which proves that the stability of wind resistance is better.The increase of stiffness of cable and tower girder directly leads to the increase of stiffness of the whole bridge,the increase of dead load concentration,the increase of dead load concentration and the decrease of natural vibration frequency of the structure.(5)This paper expounds the key links involved in the construction stage of the bridge and the important work of construction monitoring,evaluates the construction links of the bridge based on the measured data collected from the construction site of the project.The construction quality of the main tower of the bridge is better,the main girder and cable shape are in good agreement with the design state,the construction of suspension tension and main cable saddle is more precise and controllable,and the construction and monitoring work of the bridge can be done.It provides a reference for the construction of similar bridges.