| The glass curtain wall structure is widely used in modern cities,and the cable is a key component,so the monitoring of its cable force is very important.The frequency method is simple in operation and high in precision.It is a commonly used method for testing cable tensions at present,but most of them are applied to bridge engineering,and the curtain wall structure is less involved.This paper is based on the single-layer cable-stayed glass curtain wall cable tension monitoring project of T3 A terminal building of Chongqing Jiangbei International Airport,105 transverse cables are studied.It is found that there are some errors in the results of testing the glass curtain wall horizontal cable by frequency method,which needs further research.The main work and conclusions of this paper are as follows:(1)The two-dimensional and three-dimensional finite element models of the horizontal cable are established by using the LINK10 unit and the BEAM188 unit in ANSYS.The cross section of the cross cable is replaced by the circular cross section instead of the actual section,and the prestress is established in the horizontal cable by the cooling method.(2)Using the above finite element model,the horizontal cable of the non-steering device is completed(that is,the adjusting end at one end and the fixed end at the other end),and the horizontal cable of the tensioning section(that is,one end is the adjusting end and the other end is the steering device),and the fixed section is horizontally The vibration frequency simulation analysis of three types of horizontal cables,that is,one end is a fixed end and the other end is a steering device,and whether or not the influence of the anchor is considered is considered.(3)From the comparative analysis of the simulation analysis results and the measured results,it can be seen that: 1)Compared with BEAM188 element,the measured frequency of LINK10 element is closer to the simulated frequency of BEAM188 element considering bending stiffness,indicating that the bending stiffness of horizontal cables has some influence;2)The comparative analysis shows that there are adjusting end anchors at one end and fixed end anchors at the other end of the non-steering horizontal cable.Whether the LINK10 element or BEAM188 element is used,whether the anchorage is considered or not has a great influence on the simulation results.On the contrary,only one end of the tension section or the fixed section of the horizontal cable with steering device has an adjusting end or a fixed section anchorage,and the other end is steered by the steering device without anchorage.Whether using LINK10 unit or BEAM188 unit,the anchorage has less influence on the two types of horizontal cables with steering device;3)For the horizontal cable without the steering device,the measured frequency is between the simulation frequency of the fixed end of the BEAM188 and the simulation of the anchoring of the BEAM188.The actual constraint at both ends of the horizontal cable without the steering device is closer to Solid support;4)For the horizontal cable with steering device,two-dimensional and three-dimensional simulation analysis is carried out,and the two are mutually confirmed.The final result is the same,that is,the measured frequency is between the simulated frequency of the hinged ends and the simulated frequency of the fixed ends.Between,and the measured frequency is closer to the analog frequency with one end hinged and one end fixed,indicating that the actual constraint of the horizontal cable of the steering device is between the ideal hinge and the ideal solid support.(4)According to the analysis results of finite element software ANSYS,the measured and simulated frequencies are fitted by MATLAB software.Based on the different requirements for ease of use and accuracy in actual testing,the existing string theory formula and beam theory formula are modified.And the calculation formula of the cable tension of the fixed section of the known tension section and the calculation formula of the cable force of the estimated section frequency of the tension section are given.(5)The finite element software ANSYS was used to simulate the cable at different angles.It was found that the error between the cables at different angles was very small.Therefore,the modified string theory of the cable without the steering device horizontal cable was tested by the dynamometer tested by the bow dynamometer.The beam theory formula is corrected to verify that the verification results are good.The modified cable theory and the modified beam theoretical formula of the steering cable are verified by the design cable force,and the verification results are good.(6)The influence of elastic modulus change on cable force calculation is discussed.The analysis results show that the influence of elastic modulus on vibration frequency can not be ignored,and the smaller change of elastic modulus will cause a larger change in simulation frequency,thus increasing the deviation of simulation cable force calculation results.Therefore,it is necessary to test the elastic modulus of the cable before using frequency method to test and analyze the cable force,and to use different methods to detect the cable force in parallel.It can accurately determine the values of relevant parameters and improve the accuracy of cable force calculation. |
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