| The self-anchored suspension bridge is a new type of bridge structure developed based on the traditional structure of the anchor suspension bridge.The biggest difference between selfanchored suspension bridges and ground-anchored suspension bridges lies in the different anchoring positions of the main cables.The anchored suspension bridge anchors the main cable in the huge anchorage,while the self-anchored suspension bridge anchors the main cable directly to the main beam.As a result,a self-balancing system consisting of a bridge tower,a main girder and a cable is formed.The overall force distribution and vertical stiffness distribution of the bridge are greatly changed with respect to the anchor suspension bridge.The beam will directly bear the horizontal component of the main cable and generate a large axial pressure in the beam,which is equivalent to the prestress applied by the main cable to the main beam.This prestress improves the bending stiffness of the main beam.The unique structural characteristics and stress characteristics of self-anchored suspension bridges have,to a certain extent,broadened the scope of application of suspension bridges.In recent years,self-anchored suspension bridges have been increasingly favored by bridge builders for their aesthetic,economical advantages and flexible location selection,and are widely used in practical projects.In this paper,with the Zhaojiang Xiangjiang Bridge in Hunan Province as the engineering background,the study of the stress distribution and vertical stiffness distribution of asymmetrical self-anchored suspension bridges with single-towers and different span-to-span ratios is carried out,which can be used for the comparison and structural design of the structural bridges.And structural optimization provides some valuable conclusions.Firstly,the main theory of current main cable shape of suspension bridge is introduced: the theory of segmented catenary,segmented parabola theory,piecewise linear theory,finite element theory and so on.Based on the theory of segmented catenary,based on ANSYS finite element analysis software,this paper divides the main beam system and cable system of selfanchored suspension bridge into two parts for analysis to obtain the main cable shape that meets the design requirements and uses APDL.Language programming for self-anchored suspension bridges;Then,by changing the cross-span ratio and keeping other parameters unchanged,bridge models with different span-to-span ratios were obtained,and the internal force variations of the towers,girders,cables,and other components under different cross-span ratios were analyzed and compared.The asymmetry of the span of the bridge will also affect the distribution of the internal forces of the main span and the side span,resulting in the asymmetry of the forces of the main span and the side span.However,the change in the ratio of the span to the span does not affect this kind of force.Symmetry will have a certain effect;Finally,due to the unique self-balancing system of self-anchored suspension bridges,the composition and distribution of the overall vertical stiffness of the self-anchored suspension bridge is very different from that of the ground anchor suspension bridge.The vertical stiffness of the self-anchored suspension bridge consists of two components: the gravity stiffness of the main cable under load and the geometric stiffness of the tower tower,main girder,and cable combination to resist vertical deformation.In this paper,the influence of the vector-to-span ratio on the gravity and geometrical stiffness of self-anchored suspension bridges and the respective proportions of the two stiffnesses in the overall vertical stiffness are studied using the control variable method. |
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