| Transmission towers are the support points of overhead lines and are a vital component of power transmission lines.Older transmission towers generally have a reduced load-bearing capacity due to their long operating life,and have an increased risk of collapse in typhoons.A large number of transmission tower collapse accidents show that transmission tower damage in typhoons mainly comes from the internal component destabilization damage,so it is necessary to study the transmission tower reinforcement from the perspective of stability.The existing reinforcement solutions for transmission towers have disadvantages such as installation difficulties and openings in the original tower material.In this paper,the buckling restrained bracing principle is applied to the transmission tower reinforcement,and an angle buckling restraint reinforcement scheme is proposed.This is a reinforcement method for the original angles of transmission towers.This scheme improves the bearing capacity of transmission towers and does not open holes in the original towers,which can effectively control the failure of transmission towers due to the overall instability of the poles,which is of great help to the overall stability and significantly improves the deformation capacity of the towers.It has great application prospects.The main research content and results of this paper are divided into the following three parts:(1)Design four kinds of flexural restraint structure and carry out the angle steel flexural restraint member test research,based on 8 angle steel static test,the angle steel members in different length and slenderness ratio of the four kinds of angle steel flexural restraint reinforcement scheme mechanical performance research,analysis of the member damage pattern,ultimate bearing capacity and overall stability,research shows that: according to the test results to obtain the ultimate bearing capacity of all test pieces,four kinds of structure relative to the original The ultimate bearing capacity of transmission tower is increased by 101.3%,57.04%,49.80% and 27.74% respectively.The strains of all members when reaching the ultimate load capacity as the overall strain increase rate,the four configurations increased by 61.69%,30.24%,38.79% and 20.44% respectively compared with the original transmission tower material.(2)Based on the test,ABAQUS finite element model was established to compare the test and finite element results to verify the accuracy of the model in terms of damage pattern and ultimate bearing capacity.Based on the test data,we established four overall buckling constraint principal structure models and used them to establish simplified finite element models,which can more accurately simulate the mechanical properties of the test members and improve the speed of finite element calculation,providing a reliable basis for the subsequent dynamic calculation of the transmission tower-line system.(3)On the basis of component level analysis,a tower-line system finite element model with two lines is established,and wind vibration analysis is performed on the tower-line system.The AR method is used to simulate the pulsating wind load and to clarify the ultimate wind speed and damage mode of the transmission tower under strong wind.The accuracy of the simplified model is verified by three aspects: modal analysis,tower top displacement and rod axial force.And on this basis,the simplified model is used to strengthen the transmission tower,and the local weak position strengthening scheme is adopted for the transmission tower.A total of three types of angle buckling restraint reinforced transmission towers are designed for analysis,and the results show that: the ultimate wind speed increases from 34m/s to 38m/s after the transmission tower-line system reinforcement,which verifies that the angle buckling restraint reinforcement method has good reinforcement effect. |
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