| Self-anchored suspension bridges have been developed rapidly due to their strong adaptability to terrain conditions and aesthetic features of their own structural modeling.However,due to its special mode of force,the stiffening beam itself has to bear the huge axial force caused by the main cable tension,so that the stiffening beam becomes an eccentric compression component,which is manifested in the static and dynamic characteristics,and makes the force of the whole bridge structure more complex.In this paper,the static and natural vibration characteristics of self-anchored suspension bridge are analyzed by finite element method.The main research contents,methods and results are as follows:(1)Based on the actual engineering background,this paper uses finite element software MIDAS/CIVIL to establish the spatial finite element discrete model of the whole bridge,and simulates the final bridge state finite element model by "one-time bridge completion" method.(2)By considering the structural dead weight,second-stage dead load,lane and crowd loads,wind loads and temperature loads,the effects of constant load,live load and combined load conditions under constant load are analyzed respectively.The results show that under different load conditions,the structural members of the whole bridge have good mechanical performance.Under the combined load,the static response values are larger,but they all meet the requirements of design specifications,which is of great significance to the safe operation of bridges.(3)Based on the spatial finite element model of static analysis,the self-weight and second-stage dead load are transformed into mass.The self-vibration characteristics of the whole bridge are analyzed by multiple Ritz vector method,and the main vibration characteristics of the whole bridge structure are obtained.The main mode shapes are transverse bending,vertical bending,torsion and transverse displacement of main cable.(4)By changing the main structural parameters such as stiffness of the main structural components,second-stage dead load concentration and the length of the extended span of the stiffening beam,the effects of single parameter and multi-parameter changes on the static and natural vibration characteristics of the structure are analyzed.The influence analysis of single parameter change shows that the change of main cable tension stiffness and stiffening beam flexural stiffness has great influence on the static and natural vibration characteristics of the structure;the change of second-stage dead load concentration of stiffening beam mainly affects the lateral and vertical stiffness of the structure;the change of bridge tower and suspension cable stiffness has little influence on the static and natural vibration characteristics of the structure;the increase of the extension span length is the main factor.The flexural moment and deflection of the structure under live load are greatly affected.In terms of the natural vibration characteristics,the change of the extension span length has little effect on the overall stiffness of the structure.(5)In the analysis of the influence of multi-parameter change,as an important structural component of self-anchored suspension bridge,the change of stiffness of main cable and stiffening beam at the same time has a greater impact on the static force and natural frequency of the structure.With the stiffness of the main cable and stiffened beam increasing at the same time,the main mode frequencies of the structure are increasing.It shows that the overall lateral and vertical stiffness of the structure is increased with the stiffness of the main cable and stiffened beam increasing at the same time.The stiffness of main cable and suspension cable and the stiffness of main cable,suspension cable and stiffened beam have similar effects on the static and natural frequencies of the structure,and the static control index values and vibration mode frequencies are similar.In the analysis process of this paper,according to the relevant calculation and analysis of the finite element model,it provides guidance for the part of the bridge construction.At the same time,the relevant conclusions drawn from the corresponding analysis results in this paper can provide corresponding reference for the design and calculation of the same type of bridge to a certain extent. |
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