Research On Bending Behavior Of Parallel Steel Wire Cable

Steel cables are widely used in modern structures such as bridge construction,prestressed structures,cable-membrane structures because of their good tensile properties and lightweight shape.Generally,steel cables consist of steel wires twisted through a certain way,which can be divided into wire ropes,spiral strands,steel wire cable,steel rods and stiff cables.The bending performance of cables is one of the most important properties of cables,which has great influence on the measurement of cable forces and the active control of cables.At the same time,at present,scholars at home and abroad have studied the bending stiffness of cables more,but there has never been a unified calculation method of the bending stiffness of cables,which brings inconvenience to the application of engineering.Therefore,it is necessary to study and analyze the bending performance of cables and propose a unified calculation method of bending stiffness for engineering application.In this paper,experimental study,finite element simulation analysis and theoretical analysis are carried out for the bending behavior of parallel wire cables.First,the bending tests of parallel steel wire with different section types and lengths were carried out according to the mechanical model of simply supported beams,and some specimens were unloaded after secondary loading.The test results showed that the transverse load and deflection curves of parallel steel wire cable without prestressing force are roughly double folded lines,and all the specimens cannot return to the initial straight state after unloading,and have larger residual deflection.There are two kinds of curves between transverse load and displacement of steel wire bundles with pre-tension:straight line and double folded line.The shapes of the curves are related to the section and length of steel wire bundles.The three-dimensional model of steel wire cable is established by finite element software.After verifying the validity of the model,the variation laws of bending deformation,displacement,stress,strain and energy of steel wire cable are analyzed and discussed.Parametric analysis shows that the strength grade of steel wire has no effect on bending stiffness,while the friction coefficient has little effect on bending stiffness.The finite element analysis indicates that the steel wire is in bonding state when the bending deformation is small,and more and more steel wires are in sliding state with the increasing of the bending deformation.The change of the state of the steel wire makes the bending stiffness of the steel wire cable change.The steel wires of steel wires cables with and without pre-tension have the characteristics of bending around their neutral axes when the bending deformation is large.The effective bending stiffness EI₀ and the bending stiffness coefficient k of the specimens are calculated by the mechanical formula,and the calculation results showed that the diameter of the section,boundary conditions and span have great influence on the effective bending stiffness.After secondary loading,the bending stiffness decreases,and the effective bending stiffness is close to the sum of the bending stiffness of all steel wires EI_min when the bending deformation is large.Finally,the load and deflection curves obtained from the test are fitted by mathematical method and it is found that the difference of the formulas for calculating the bending stiffness is less than 15%when the transverse displacement is greater than 10 mm.