Research On Method Of Measuring Cable Force Of Steel Strand Cable Based On Detailed Analysis

It is very important to calculate the alignment of stay cables and the force of stay cables during the construction of stay cables.The parameters such as stress-free length obtained by linear calculation have a guiding role in the fabrication and construction of stay cables.Considering the factors such as convenient operation and cost-saving,the vibration frequency method is often used in the calculation of cable forces,but the applicability of this method in parallel stranded stay cables needs to be studied.Based on the engineering background of Huaihe Bridge in Xinyang,this paper studies the alignment and cable force of cable-stayed cables.The main research contents and conclusions include the following aspects:(1)Introduce the deduction process of cable alignment theory,get the curve equation of cable shape and relevant parameters such as the length of stress cable,summarize the calculation model and theory of cable force measurement by frequency method,classify the errors caused by influencing factors in the process of testing cable force,and put forward the reduction measures in construction and the correction methods in calculation.(2)Based on the theoretical equation of cable type,the fundamental causes of the internal contact of parallel strand cables are analyzed,and the possible factors are analyzed one by one.The finite element model of cable shape is established by using ANSYS software to calculate the parameters needed in the construction and calculation process,such as the length of stressed cables.(3)Aiming at the complicated contact state and disordered spectrum of strand,the structure of cable-stayed cable is analyzed in detail.The internal effect of structure is divided into the mutual interference of internal steel bundles and the influence of external sheath on internal steel bundles.Based on the ANSYS software,the single strand model and the contact model of the internal steel bundle are established to study the influence of the interference between the internal steel bundles on the frequency method test.Aiming at the influence of the external sheath on the internal steel bundle,the two-beam coupling model considering the different physical parameters and mechanical characteristics is established,and the stiffness of the casing is considered to analyze the different contact areas,and the outer sheath of the cable is studied.The concrete influence of sheath on the natural frequency of internal steel bundle is analyzed,and the feasibility of vibration frequency method for parallel steel strand cable is analyzed.(4)Applying the theoretical analysis results to the construction of Xinyang Huaihe Bridge,the vibration consistency between the external sheath and the internal steel bundle is verified according to the measured results of different locations of the vibration picker,and the calculation formula is modified according to the influence of incomplete contact between the external sheath and the internal steel bundle.