Experimental Study And Stress Analysis Of Suspension Angle In Tower

With the increase of electricity consumption in various fields,the speed of electric power construction in China is gradually accelerating,and the transmission tower line,as the most important component of power system,is becoming more and more large and complicated with its voltage level and scale,and the uncertainty factors of transmission tower structure and its dynamic characteristics gradually increasing.This paper relies on a DC transmission line project,in which the ZAJ151 overhanging corner tower has many working conditions,complicated node structure and lack of mature engineering experience.The tower of this paper is calculated by TTA3.0 software written by Northeastern Institute,the ANSYS software is used to establish the beam-column hybrid structure for numerical simulation.In order to verify the reliability of the calculation,the true test of ZAJ151 tower is carried out.In this paper,the testing scheme of tower is introduced in detail,through calculation,representative working conditions are selected for the test,and the load is converted into a node load,the load is applied to the corresponding nodes of the tower by wire rope.Then determine the position of displacement and strain observation points.Collect technical data on the strength,deformation and stability of the main members under different control conditions.This transmission line passes through the karst landform,there are caves and voids underground,and the foundation of the transmission tower will be settled,inclined and slipped.This paper simulates the settlement of the foundation by releasing the degree of freedom of the tower foot joints and exerting displacement on the tower foot,and then analyses the difference of the internal force and deformation of the tower legs in different joint modes.According to the principle that the strength of the main material and the stable bearing capacity are equal,the optimal calculation length of the main material of the tower body is derived.The dynamic effect of fluctuating wind on the tower can not be neglected,for convenience in engineering,only static wind load is considered,the concept of wind vibration coefficient is introduced.Kaimal wind speed spectrum is used in this paper,the wind speed simulation program was written with Matlab software to convert the wind speed into wind pressure,and get the wind load applied to the tower,for the test tower,the rationality of the wind vibration coefficient of the tower is discussed.The following is a brief description of the main work and research results of this paper:(1)By comparing the difference of measured displacement,internal force and theoretical calculation value,the reasons for different values are analyzed,the attribute definitions of some members in the finite element model are modified to make the analysis results closer to the true type test and an accurate dynamic analysis model of the tower is established.(2)Through the study of the foundation settlement,it is found that even if a small vertical displacement of a single leg of the tower occurs,the tower loses stability.When the foundation settlement method is different,the force tendency of tower legs is similar with the legs in different joint modes.But the maximum deformation of foundation allowed by the public leg is better than the ordinary leg.(3)Through modal analysis,the calculation formula of the natural vibration period suitable for this tower type is deduced.Through the study of wind-induced vibration coefficient,it is concluded that the wind-induced vibration coefficient of HVDC transmission tower is larger than the calculated value of the regulation because of its long cross arm.The value of wind-induced vibration coefficient should be increased appropriately in design.When optimizing the weight of the tower,the front and side can be calculated with different wind vibration coefficients.