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In order to reveal the galloping mechanism of ice-coated conductors on transmission lines, the galloping wind tunnel test of ice-coated conductors was carried out. The galloping characteristics of flexible ice-coated conductors were studied by changing wind speed, wind direction, sag and other parameters. Research shows that the ice-coated wire deforms to an equilibrium position under wind load, and vibrates in multiple modes around the equilibrium position. The average deformation and amplitude of the ice-coated wire in the downwind direction are the largest, and increase with the increase of wind speed. A three-tower four-line coupled system model is established by numerical simulation, and the galloping response of the tower-line system is given. The calculation results show that the icing wire begins to dance at the equilibrium position at 2 m from the initial position, the wire amplitude continues to increase, the trajectory of the dance is elliptical, and the vertical amplitude of the wire is significantly greater than the horizontal amplitude. At the same time, based on the fatigue cumulative damage criterion, the galloping fatigue damage and fatigue life of the key nodes of the transmission tower are further evaluated. The study found that the intersection of the upper and lower curved arms of the wineglass tower line system is the key node that is most prone to fatigue failure during the galloping process. The fatigue damage of the components at the intersection of the upper and lower curved arms should be fully considered in the design process of the transmission tower. Finally, the galloping fatigue life of the main key nodes of the transmission tower is given. [ABSTRACT FROM AUTHOR]

To solve the problems of poor tensile performance and long construction period of traditional pile-tower foot cast-in-place joint, a new type of precast high-strength concrete pile (PHC) pile-tower foot mechanical joint was proposed. The minimum thickness of cylinder and web in the new joint was determined by theoretical analysis, and then finite element analysis of axial performance was carried out by ABAQUS and compared with the traditional cast-in-place joint. The results show that when the thickness of the cylinder is 10 mm and the thickness of the web is 10 mm, it can meet the single load capacity requirement, the overall load capacity requirement and the economic requirement. Under the compressive load, the traditional cast-in-place joint will be damaged by buckling in the whole area of the tower foot. The mechanical joint will be damaged by buckling in the whole area of the cylinder and web in the main body of the joint, which can meet the compressive design bearing capacity requirements of the same type of pipe pile-tower foot, and can choose to increase the thickness of the cylinder and web to improve the overall compressive bearing capacity. Under the tensile load, the cast-in-place joint eventually breaks due to the lack of anchoring force between the anchor bar and concrete in the pre-built parts, and the tensile displacement is all rigid displacement of the pre-built parts, and the joint has very poor ductility. The mechanical connection joint is eventually damaged by the excessive tensile deformation of the connection pin in the engagement type connection joint, and its tensile bearing capacity is much larger than the cast-in-place tensile bearing capacity and has better ductility. [ABSTRACT FROM AUTHOR]

In order to improve the ability of transmission towers to resist extreme meteorological disasters in service and ensure the safe and stable operation of transmission lines, a typical 220 kV transmission tower is taken as an example, and the finite element method is used to study its wind resistance ultimate load bearing capacity and analyze the collapse mechanism and damage mode of transmission towers under strong wind. In view of the failure mode of the transmission tower, a non-destructive reinforcement scheme is proposed. By establishing finite element models of angle steel members with different length to slenderness ratios of the main material, the axial compression load capacity of the main material before and after reinforcement is numerically simulated, also the reinforcement design is carried out for the main material of the weak part of the transmission tower, and the ultimate wind bearing capacity of the reinforced transmission tower is studied. The results show that the reinforced main material angle bearing capacity is greatly increased, up to 37.2%. The local stiffness of the weak parts of the transmission tower is improved, the top displacement and the maximum stress of the tower are significantly reduced compared with those before reinforcement, the ultimate bearing capacity of the tower is greatly increased, and the design importance factor of the transmission tower is increased from 1.15 to 1.35. The proposed reinforcement method can provide an important reference for the wind resistance reinforcement design of the same type of transmission tower. [ABSTRACT FROM AUTHOR]