Research On Wind Resistance Reliability Of Transmission Tower-Line System Based On Mixed Probability And Interval Uncertainty Analysis

As the physical carrier for transmitting high-voltage electrical energy in the power system,transmission lines are responsible for the basic responsibility of guaranteeing electricity for enterprises and residents.In recent years,wind-caused damage and collapse of transmission lines have frequently occurred in cities near the sea in China,seriously affecting the safe operation of transmission lines,and these accidents have directly or indirectly led to substantial economic losses and secondary disasters affecting the normal operation of cities.Therefore,it is necessary to make an accurate assessment of the transmission tower’s safety.The transmission tower’s safety is assessed by studying the transmission tower’s reliability,where the main quantitative index of the assessment is the transmission tower’s reliability index,therefore,it has important scientific value and engineering significance to study the reliability calculation method of the transmission tower system.Nowadays,the existing calculation methods of reliability of transmission tower system do not have effective measurement of uncertainty of interval parameters and subsequent structural reliability research,there is not much researchs on transmission tower’s failure mode,there is also little literature about reliability analysis based on the ultimate bearing capacity state.According to this,this paper combines the elastic modulus reduction method of structural ultimate bearing capacity analysis and the reliability calculation method of mixed probability and interval variables,and proposes a transmission line wind-resistance reliability calculation method to study the wind-resistance reliability.The main steps of the research method are as follows.(1)A wind load calculation program based on the equivalent random static wind load model is written in MATLAB to get the random wind load on the transmission tower line.(2)Calculate and analyze the transmission tower line’s ultimate bearing capacity under wind load by the elastic modulus reduction method,and obtain the failure mode,then establish the functional function of wind-resistance failure of the transmission tower line system based on the ultimate bearing capacity analysis.(3)Introducing multi-ellipsoidal convex set model and establishing the descriptive model of the transmission tower line system interval variables as horizontal and vertical gear distance.(4)Introducing the mixed interval and probabilistic uncertainty analysis methods,combining the equivalent extreme value event and elastic modulus reduction method to establish the wind-resistance failure function of the transmission tower line system,and proposing the wind-resistance reliability calculation method for the mixed interval and probabilistic uncertainty of the transmission tower line system under the two limit state assessment methods.The wind-resistance reliability of the transmission tower line system is analyzed by using the hybrid interval and probabilistic uncertainty of the wind-resistance reliability calculation method under the limit state assessment method proposed in this paper.The study shows that.(1)The failure mode of the transmission tower line system can be identified according to the size of the elastic modulus reduction,and the failure path of the angle steel rod in the transmission tower structure under the failure mode can be determined,and the failure mode of the transmission tower line system can be obtained,specifically the plastic failure will occur when the unit member reaches the ultimate bearing state,and the failure of the main material of the tower neck on the tension side,and the location of the main material of the tower neck on the compression side is the failure unit The main distribution position of the member,the main material of the tower leg has a small number of failed rods,compared with the tension side,the compression side has more failed units.(2)The interval convex set model and the multi-ellipsoidal convex set model are two models that can better describe the interval range,and the combination of one or more sets of these two models can establish the interval variable description model considering correlation.(3)The reliability calculation procedure of mixed stochastic and interval uncertainty analysis hai made in the reliability calculation method of the transmission tower line system,With this procedure,we can directly calculate the wind-resistance reliability results of the transmission tower line system,it will be very efficient and can ensure accuracy and applicability.(4)Wind speed and wind angle are the control parameters of the wind-resistance design of the transmission tower system,through which the wind-resistance reliability of the transmission tower can be evaluated,the horizontal and vertical file distance is the main control parameter that makes the transmission tower’s failure probability,and the maximum failure probability is gotten when the horizontal file distance is the maximum.