Research on Optimal Sag-to-Span Ratio of Main Cables of Highway Suspension Bridge Based on Engineering Economy
This study focuses on the selection of sag-to-span ratio of main cables for the highway suspension bridge that will bring maximum economic benefits.Multiple highway suspension bridges featuring concrete towers and single suspended spans in China were surveyed.Direct function models of engineering quantity of main cables,anchorages,and foundations as well as a nonlinear function fitting model of the engineering quantity of the concrete towers were established,by which suspension bridges of 952 structural configurations were collected to investigate the relationship between the sag-to-span ratio of main cables and engineering economy.The 952 structural configurations were statistically categorized in accordance with the span lengths(between 750 mm and 2 250 m),vehicle lanes layout(4 to 8 lanes on a single deck and 6+4 lanes of a double decker),and sag-to-span ratios(between 1/14 and 1/6).Two existing bridges were selected to analyze the influence of the sag-to-span ratio on the static and dynamic properties as well as wind resistance of suspension bridges.It is shown that the sag-to-span ratio of main cables is closely related to the engineering economy of a suspension bridge.Span length is a critical factor in the sag-to-span ratio of main cables of a suspension bridge,the influences of lane amount and load concentrations of the stiffening girder are relatively minor,and no obvious difference is found between the bridge having in-water components and the bridge having no in-water components.For the suspension bridges with main span lengths between 750 m and 2 250 m,the optimal sag-to-span ratios of the main cables should be between 1/6.5 and 1/8.5,much larger than the empirical values.As per the analysis of the two real bridges,increasing the sag-to-span ratio will lead to the increase of the deflection and live-load-induced stresses in the stiffening girder,and the enhancement of the wind resistance as well.It is suggested to enlarge the scope of the sag-to-span ratio study at the preliminary design stage and comprehensively compare the engineering economy and mechanical property of the bridge.
suspension bridgesag-to-span ratio of main cableengineering quantity modelengineering economymechanical propertybridge design
万方数据
维普
