| The single-tower mixed beam self-anchored suspension bridge has a novel structure and beautiful appearance.With the development of modern productivity and the improvement of people’s demand,the span requirements of various types of bridge are also increasing.Therefore,it is necessary to study the ultimate span of single-tower mixed beam self-anchored suspension bridge,the reasonable length of steel beam and the range of reasonable structural parameters.Based on the engineering background of a single-tower mixed-beam selfanchored suspension bridge in Guangdong Province,this paper studies the ultimate span,reasonable length of steel beam and reasonable range of structural parameters of the singletower mixed-beam self-anchored suspension bridge.(1)Based on the material strength requirements of the main beam and cable during the operation of the single-tower mixed beam self-anchored suspension bridge,the ultimate span formula of the single-tower mixed beam self-anchored suspension bridge is derived,considering the influence of the parameters such as the beam span ratio,the span ratio of the main side span,the height span ratio of the tower beam,the length ratio of the main span concrete beam to steel beam and the distance between the suspender.The correctness of the formula is verified by comparing the theoretical ultimate span of the main beam with the corresponding finite element model.Combined with the material characteristics and structural parameters used in self-anchored suspension Bridges with single-tower mixed beams,the effects of length ratio of main span concrete beam to steel beam,main span vector span ratio,tower beam height span ratio and side span span ratio on ultimate span in single-tower mixed beams are illustrated by numerical examples.Based on the beam theory and the pressure bar theory of elastic foundation,the calculation formula of the stability of the main beam is derived,and the relation curve between the stability of the main beam and the span is obtained.On this basis,the relationship between the span and the stability of the main beam is explored.(2)Using finite element software and single variable method,the internal forces and deformation data under different lengths of steel main beams are obtained,including internal forces of suspender,internal forces of main cable,bending moment of main beam and deflection of main beam,etc.By analyzing the finite element model data,the reasonable length of steel beam is about 352 m.(3)The reasonable range of parameters of single-tower mixed beam self-anchored suspension bridge was explored by using the finite element software simulation analysis with the distance of boom,tensile stiffness of main cable,vector span ratio and dead load concentration as the research parameters.By changing the distance between the suspender,the tensile stiffness of the main cable,the ratio of the span and the degree of dead load in turn,the internal forces and deformation data of the structure under different parameters were obtained through the finite element analysis.Through the analysis and summary of the finite element data,the reasonable parameter range of the self-anchored suspension bridge with single tower mixed beam was obtained: the reasonable distance between the suspender should be between 10.5m and 12 m.The reasonable range of tensile stiffness of main cable is 1.0-1.3times.The reasonable range of vector span ratio is between 1/11.5 and 1/12.5.The dead load concentration of self-anchored suspension bridge with single tower mixed beam is designed and distributed safely according to the mechanical performance of the structure.The research results can supplement the calculation theory of the ultimate span of this kind of bridge,and provide a certain reference for the reasonable length of steel beam and the range of structural parameters. |
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