Method Of Damping Ratio Calculation And Seismic Analysis Of Suspended Converter Valve

Damping ratio,to select an accurate and reasonable value for a special engineering structural,will directly affect the authenticity of the structural response results and the correctness of the structural damage detection results,and it will also affect the reliability and economy of the actual engineering.The damping ratio of the suspended converter valve tower is calculated,and the damping forms in five methods of seismic analysis are compared and studied in this thesis.The main work and conclusions are as follows,(1)The damping ratio and frequency of a simplified suspension model are calculated using HHT Modal Parameter Identification and a simulation software.The results show that the HHT Modal Parameter Identification is suitable for the parameter identification of suspended converter valve in the calculation of damping ratio and natural frequency,because it is not subject to Heisenberg’s uncertainty principle and has self-adaptive characteristics,and the high-order mode damping ratios of the suspension model are larger than the low-order modes,which is consistent with the regulation of the mode damping ratio of general structural and the results of the simulation software.The above results show that the HHT Modal Parameter Identification is suitable for calculation of the damping ratio and frequency parameters of the suspended converter valve.(2)A finite element model of a suspended converter valve is established using ANSYS software,and the HHT Modal Parameter Identification is used to identify the damping ratios and frequency based on its response under non-stationary random excitation,and the effective IMF components are filtered through correlation coefficients,and the first six-order mode damping ratios and natural frequency of the valve tower are calculated.The results show that the calculation results of the natural frequencies are consistent compared with the ANSYS modal analysis results,and the damping ratios gradually increase from low to high.The calculation formula of the overall structure is used to obtain the damping ratio of the suspended converter valve.The structural damping ratio calculated in this thesis is 2.5%,which is relatively close to 2.0% suggested by the Code for seismic design of buildings.(3)The design acceleration response spectrum is adjusted in the view of low frequency characteristics of the suspended converter valve,and an artificial seismic wave is constructed based on the finite element model of the suspended converter valve in Chapter 3.The Full Method under Rayleigh damping,Response Spectrum Method,as well as Modal Superposition method under Rayleigh damping,constant damping and modes damping for seismic analysis of suspended converter valve are analyzed and compared.The results show that the artificial seismic wave constructed in this thesis has long-period characteristics and is suitable for seismic analysis of suspended converter valve which is contained abundant low-frequency components.The seismic response of suspended converter valve is quite different using different damping forms of seismic analysis methods,and the Mode Superposition method with calculating the first 30 modes’ damping ratios involves more low-frequency ranges compared with the Full method using Rayleigh damping which only contains the first two modes,and its response results of the converter valve are more severe.The Mode Superposition method using mode damping ratio can be used for seismic analysis of suspended converter valve,and it is more reasonable compared with the traditional Full method using Rayleigh damping.