Parameter Identification And Generalized Modal Flexibility Theory Of Frame Structure Based On Dynamic Angle Measurement

When the structure identification algorithm was applied to practical engineering,the structure angle information was difficult to accurately measure and the degree of freedom of rotation was often neglected.The method of measuring dynamic signals with gyroscope sensor and the identification of structural physical parameters and modal flexibility under the dynamic rotation Angle measurement information were studied in this paper.This paper mainly studies the following aspects:(1)To solve the problem of difficult measurement of structural rotation angle response information,a commercial Micro Electro Mechanical Systems(MEMS)gyroscope sensor was proposed to measure the angular velocity and angle responses,the existing MEMS gyroscope sensors in the market were investigated,and the basic working principle of HWT901 B gyroscope sensor was introduced.Through numerical simulation and experimental research,based on the principle of fitting rotational response from translational response information,the static accuracy and dynamic accuracy of MEMS gyroscope sensors were verified by taking column members of portal steel frame structure as test objects,which provides support for subsequent static load tests and modal tests.(2)Under the condition of incomplete output information,the theoretical formulas of structural physical parameters identification method based on the least square recursive method were deduced.Taking a four-story frame construction as an example for analysis,two working conditions that the rotation angle reconstructed by the generalized inverse method and the adoption of the true value of rotation angle were set up,and the physical parameters was identified,it verified the correctness of the theoretical derivation.The results of physical parameters identified under two working conditions were compared,which reflected that the effects of physical parameter identification was not very ideal when the angular response was reconstructed.The measured dynamic test data and analysis results of a three-story and two-span steel frame model verified that using Micro Electro Mechanical Systems(MEMS)gyroscope sensor to directly measure the rotational response was better than using reconstructed rotational response for the time domain identification of the stiffness parameters of the bending-shear structure.On this basis,the damage of the steel frame was further identified by the least square method,and the damage range was accurately diagnosed.(3)Based on the multi-span plane frame structure model considering node rotation and different modal test information,the sensitivity method was used to identify the interlayer bending stiffness parameters and damage of the steel frame model.The results show that the anguler shape test information was supplemented.The accuracy of the structural physical parameters identified by the sensitivity method was improved,and the damage position of the frame structure was better indicated.Comparing the damage diagnosis results of the least squares recursive algorithm and the sensitivity method,the results show that the damage identification results of the sensitivity method were relatively more accurate(4)The concept of generalized modal flexibility was proposed by introducing angular information into modal flexibility.According to the method of extracting modal flexibility based on frequency response function intercept,the accuracy of modal flexibility algorithm was verified by comparing the displacement(Angle of rotation)of the structure under static load with the displacement(Angle of rotation)calculated by modal flexibility through static load test and modal test study on the steel frame model.The results show that the displacement modal flexibility was more accurate than the angular modal flexibility,and the main error was due to the insufficient participation of the modal order,and the contribution of the first three order displacement modes to the overall displacement modal flexibility was greater than that of the first three order angular modes to the overall angular modal flexibility.