| With the vigorous development of bridge construction in China,suspension bridges are becoming more and more popular because of their beautiful alignment,reasonable stress and integration with the environment,but the lifting and installation of stiffening girder is a difficult point in the construction of suspension bridge.For stiffening girders of suspension bridges across rivers,the traditional methods will have a certain impact on their navigation,especially in dry season,it is necessary to restrict the navigation and seal the navigation without affecting the construction period,which seriously affects the transportation of past ships and causes great losses to the economy.Cable hoisting system,as a kind of lifting device which can not only be lifted vertically but also be transported horizontally over a long distance,can overcome this point well.It has the advantages of easy operation,easy control,convenient construction,no need to erect brackets,strong adaptability to various environments and strong lifting capacity.Therefore,cable hoisting system is more and more widely used in the field of suspension bridge engineering.With the continuous progress of bridge construction technology,the span of suspension bridge is getting longer and longer,and the stiffening girder section is also getting heavier and heavier.Therefore,the design and research of cable hoisting system with long span and large tonnage is inevitable for the future development.Based on the engineering background of the cable hoisting system of Changshou Yangtze River Second Bridge,this paper analyses and studies the important components of the cable hoisting system.The specific research-work and results are as follows:1.This paper discussed the calculation theory of the main cable of the cable hoisting system.The calculation formulas of linear,Length of main cable and the skyline tension are deduced by the application of theory,which provides a theoretical basis for the subsequent calculation and analysis work.2.Comparing the parabola theory with the precise catenary theory,this paper analyzed the relative error of the two theories for the horizontal force of the main cable under the condition of long span,discussed the applieability of parabola theory in large span cable hoisting system.3.Studied and summarized the method of calculating the deformation of the main cable under the action of uniformly distributed load and concentrated load.Compared with the more accurate finite element method,the calculation accUracy of two kinds of main cable tension state equations in analytic method is analyzed,and its applicability in long span cable hoisting system is discussed.At the same time,MATLAB software is used to draw the vertical envelope diagram of several key working conditions.4.To comparison and analysis through the change of layout parameters by the means of control variable method,the influence of the angle of the edge span cable inclination and the vertical span ratio of the middle span design on the force of the main cable is studied,and the reasonable range of the design is obtained.5.With the changing of mid-span and the tensile strength of the main cable,the variation of the economy of the main cable with the span and the tensile strength is revealed.6.By setting a set of main cables with different sag of difference,the same pendulum is achieved under the load of maximum lifting and heavy working conditions,and the influence of installation error on the mechanical performance of the main cable is studied. |
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