| The long-span prestressed concrete continuous rigid frame bridge is favored by bridge engineers because of its simple structure,reasonable stress,beautiful appearance,convenient construction and many other advantages.With the requirements of the environment for the construction of the concrete beam bridge with a larger span,from the perspective of materials,the steel-concrete hybrid girder long-span continuous rigid frame bridge has gradually entered people’s vision.However,due to the lack of construction examples and the lack of research results on the design parameters of the large-span track continuous rigid frame bridge with hybrid girder at home and abroad,few of the Optimization Research on the design parameters is only carried out for the symmetrical hybrid girder continuous rigid frame highway bridge,while for the asymmetric side span hybrid girder continuous rigid frame and the more stringent requirements on the reasonable parameter design of the bridge rail transit load bridge beams are rarely involved.Therefore,based on the research of steel hybrid bridges at home and abroad,relying on the world’s largest continuous rigid frame bridge with steelconcrete hybrid beam track--Jiahua Jialing River track special bridge,this paper determines the corresponding analysis method for different design parameters and puts forward the simplified calculation model of the bridge The detailed analysis of the structural stress and deformation law of the continuous rigid frame bridge under different design parameters(parabola index at the bottom of the beam,side to middle span ratio,length setting of steel box girder,height to span ratio,etc.)determines the reasonable value range and reveals the change law of the parameter sensitivity.The main contents of this paper are as follows:1.By studying the common structural calculation and analysis methods,comparing the advantages and disadvantages of various methods,considering the particularity of the bridge structure in this paper,the structural optimization idea based on the search method is determined,the parabolic index and the height span ratio at the bottom of the beam are analyzed by the finite element method,and the span arrangement of the bridge is analyzed by the analytical method.2.In order to better analyze the design parameters of the rigid frame section,the paper analyzes the influence of the extension section of the continuous rigid frame composite bridge on the stress and deformation of the rigid frame section,neglects the factors such as the compression of the side piers and the axial deformation of the main beam,simplifies the moment unloading effect of the extension section on the rigid frame section,and puts forward a kind of research mainly aimed at the design parameters of the rigid frame section The simplified structure model of the analysis.3.Considering the dead load and live load respectively,the influence of the main beam self weight,the internal force and displacement of the key section when the parabola index of the beam bottom changes is analyzed in detail by using the finite element model,and the reasonable value of the parabola index of the beam bottom is discussed based on the obtained stress and deformation results.It is found that the selection of the parabola index value should be based on the consideration of the corresponding stress and deflection deformation safety reserve It is better to consider the smaller value.4.Set three parameter variables: the ratio of steel box girder length to main span and the ratio of unequal side span to main span.Solve the structure by analytical method,get the expression of internal force of key section,calculate its internal force value and analyze the influence rule of internal force value of key section in detail,get the reasonable value range of span layout,and be sensitive to three parameters based on the influence of internal force at the joint of steel and concrete It is found that the influence degree is: large side span > small side span > steel box girder length.5.Using the finite element method to analyze the deflection and rotation angle of the key section of the main beam when the height span ratio of fulcrum/midspan changes at the same time,and combining with the engineering experience to get its reasonable value range,and based on the deformation control,the sensitivity analysis of the height span ratio of fulcrum/midspan is carried out,and it is found that the height-span ratio of fulcrum has a more significant impact on the midspan deflection and more disturbance than that of midspan.The research results of this paper can provide a positive reference for the construction and further research of similar bridges in the future... |
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