Study On Reliability Analysis Of UHV Transmission Tower–Line System With Wind Action

The line system of UHV transmission tower, as an important large and complexlifeline project, compared with the line system of ordinary transmission tower, ischaracterized by high tower body, large span and high voltage grade and etc, belongingto typical wind load sensitive structure, therefore, the research of the reliability of linesystem of UHV transmission tower under the action of wind load is coming to be moreand more imperative. However, compared with the architecture modeling and analysisof tower-line coupling system, the study of its wind resisting reliability theory is just inearly stage. This paper, on the basis of development of reliability theory, makes asystematic research on the issues such as the wind vibration static reliability, windvibration dynamic reliability and tower body reliability based on the performance level,of the line system of UHV transmission tower, mainly including the following aspects:1) In this paper, the time-history analysis based on the wind vibration response ofwind load random model to the line system of transmission tower is made. First, theharmonic synthesis method based on random Fourier spectrum is adopted to fit the windload time-history suitable for the wind vibration response analysis of tower line, beforeverifying the coincidence of simulated time-history power spectrum with targetspectrum by means of numerical example; then using finite element program to maketime-history analysis of single tower and tower-line system respectively so as to verifythe reasonability of simplified treatment of each rod piece in finite element model oftower line, and provide favorable tool for subsequent reliability analysis.2) This paper puts forward a adaptive response surface method based on theanalysis of variable structure and sets up a thought, combined with the principle ofequivalent extreme events, for analyzing the system reliability, based on responsesurface method; at the same time, on the basis of equivalent static wind load randommodel, this paper gives a suggestion of the frame for analyzing wind vibration staticreliability of the line system of transmission tower, and furthermore, constructs areasonable high order response surface form by judging each variable item according tothe result of univariate analysis and sets up a corresponding actual algorithm bycombination with the scheme of the selecting points in number theory; and convertssystem reliability problem to a simple reliability problem of sing performance functionby use of the principle of equivalent extreme events, then adopts the adaptive responsesurface method to reconstruct the equivalent single performance function so as to set up a system reliability analysis method based on response surface; then, combined thesuggested method with equivalent static wind load random model to study the windvibration static reliability of tower line system.3) In this paper, based on the equivalent extreme events and the adaptive responsesurface method, the method for analyzing the dynamic reliability of tower line system isset up. According to the principle of equivalent extreme events, the dynamic reliabilityof structural system is converted to a simple reliability problem only involving singleperformance function and combined with adaptive response surface method and therandom Fourier spectrum synthesis of wind load, the method for analyzing the dynamicreliability of general structural system is set up. Based on this solution, this paper putsforward the method for calculation of the reliability of wind vibration of tower linesystem.4) Using for reference of the seismic design theory based on performance, thispaper proposes wind resisting performance level of the line system of UHVtransmission tower, and further, starts a research of the reliability of the line system ofUHV transmission tower based on performance. First, combined with the example ofdisasters, it analyzes the destruction form and failure rules of transmission tower intower line system, taking the displacement and partial deformation of tower top forperformance objectives, gives out a qualitative description of the4thstage level of windresisting performance of tower body structure; the paper confirms the quantitativemodel of performance level of power transmission tower according to test and standard,using finite element method to establish a mechanical model for examination of whetherquantitative value is reasonable or not, before synthesizing the both to give out thequantitative model of performance level of power transmission tower, not only meetingstandard requirements but also convenient for the needs of engineering design; thispaper makes systematic analysis of the performance reliability of different tower modelsby the analysis of the methods of wind vibration reliability of tower line systemsuggested as above.