Parameters Of Mechanical Characters Of Large Flow Multi-tower Cable-stayed Bridge Sensitivity Analysis

As a critical node engineering project in water resource allocation,water pipeline bridges play a crucial role in the entire process of water transportation.In China,water resources are severely unequally distributed,accompanied by rapid development in industry and agriculture,which continuously increases the construction demand of various water diversion projects.The construction demand for large flow multi-tower cable-stayed pipe bridges is also continuously increasing.Currently,there is not much research literature and information available on large flow multi-tower cable-stayed pipe bridges.Therefore,it is necessary to conduct research on multi-tower water pipeline cable-stayed bridges.To comprehensively analyze the mechanical characteristics of a large flow water pipeline cable-stayed bridge,this paper relies on the Shaanxi Natural Science Foundation project,"Key Technology Research on Long-Span,Large-Flow,Multi-Tower Cable-Stayed Pressure Water Pipeline Bridge(2021JLM-47)," and takes the Weihe River water pipeline cable-stayed bridge as the research background.Firstly,a finite element model is established and the stress characteristics of the large flow multi-tower cable-stayed pipe bridge are summarized.Then,the orthogonal experimental method is used to select six structural parameters for structural static sensitivity analysis,screening the structural parameters that have a greater impact on the static characteristics of the large flow multi-tower cable-stayed pipe bridge.Finally,single factor analysis is conducted on factors such as constraint conditions,tower height,side span ratio,and tower stiffness,and recommendations are given for the selection of relevant parameters.The research conclusions are as follows:(1)For a multi-tower cable-stayed pipe bridge with a large flow,the constant load effect mainly arises from the water flow load,while the live load effect is mainly controlled by the temperature load.Under the influence of water flow load,the "sub-span effect" of the water pipeline bridge is significant.The connection structure of the pipe beams can effectively enhance the stiffness of the entire bridge structure.Under asymmetric load conditions,there is a great difference in structural response between the loading side and the non-loading side The water hammer effect should be considered for a large-flow water pipeline cable-stayed bridge.(2)When the water flow load acts alone,the parameters that have a significant impact on structural deformation are the constraints and cable quantity,followed by the bridge tower height and edge-to-span ratio.When the water flow load and structural dead load act together,changes in constraints and bridge tower height will have a greater impact on the internal forces of the structure,followed by cable quantity and edge-to-span ratio.(3)The mechanical characteristics of a water pipeline cable-stayed bridge are significantly influenced by the constraints,with a semi-floating system being the preferred choice.Compared to a semi-floating system,a floating system reduces the internal forces of the structure under temperature effects,but results in a significant increase in structural deformation.In contrast,compared to a semi-floating system,a rigid system shows no significant changes in structural deflection under a constant load,but experiences a significant increase in deformation and internal forces under temperature loading.(4)The height of the towers of water pipeline cable-stayed bridges should not be too high,with a tower span ratio of 0.292 to 0.375.The bending moment and axial force of the steel truss main beam decrease as the tower height increases.When the tower height is low,the change in internal force is significant,and the rate of decrease in internal force reduction decreases as the tower height increases.The effect of the change in the edge-to-middle span ratio is opposite for the secondary and middle spans.A smaller edge-to-middle span ratio can cause the structure to have negative support reactions on the unloaded side under partial load.Therefore,multi-tower cable-stayed pipe bridges should adopt larger edge-to-middle span ratios,with edge-to-middle span ratios not less than 0.5.