Applied Mechanics and Materials Vol. 680

Abstract: To meet the needs of the economic development, the transmission power, which is the key part of Power transmission and transformation system engineering , needs to be improved on quality and quantity. Yet the design method of the transmission power has not been improved today. The outdated way of designing has many disadvantages. They don’t benefit to carry out the work of making the transmission power, and they have an enormous influence on the quality and production cost as well. Therefore, optimizing the structure, reducing the consumption of steel and improving the design level is of great significance. This article mainly uses SAP2000Nonlinear analysis of transmission tower after dao heng gradient optimization in engineering software thus reducing the consumption of steel and it can be used as a reference in a real project.

Abstract: The mechanism of soil liquefaction and the principle of enclosure method treating subgrade liquefaction are elaborated in this paper.It proves that the grid type cement soil mixing pile enclosing foundation can eliminate liquefaction based on amounts of datum and engineering case.And the means of design and construction are summarized.

Abstract: In order to study the damage problem caused by the transmission tower fatigue cracks and bolt pretightening force loss ,this paper proposes a transmission tower damage identification method based on concurrent multi-scale model, namely establish solid model on nodes of fatigue crack and bolt looseness based on large scale model., subdividing elements size. Take a practical engineering 500kV transmission towers as an example to establish a concurrent multi-scale models. This paper simulates 8 kinds of conditions including bolt pretightening force loss and angle steel crack, research shows that the sum of wavelet packet energy curvature difference can effectively identify minute damage, and then get the function relation between damage level and damage index with no noise interference, also this provides a theoretical basis for it as actual damage monitoring indicators index.

Abstract: To have a comprehensive summary of existing methods for damage identification of transmission tower so as to provide systematic and effective information, from aspeces of data sources and analytical methods, the existing methods of damage identification were summarized to sort out the technical evolution of the various damage identification methods including the static and dynamic damage identification and inversion and pattern recognition methods.Then, the application status, advantages and disadvantages of various methods were analzed, and the improvement ideas and methods were summarized. Finally, establishment of four-in-one multi-system damage identification method was proposed based on construction monitoring, loads tsets, health monitoring and artificial patrol, which is the development trend of the transmission tower structure damage identification.

Abstract: In order to analyze the mechanical properties of UHVDC transmission tower joint accurately, a multi-scale finite element model of the transmission tower is established with the interface between solid element model and beam element model. The model is applied to the nonlinear analysis of a key joint in a test condition .The results show that the tower destruction is caused by buckling behavior of the cross bracing member and the multi-scale model can simulate the force state of gusset-plate and the connected members realistically, which is superior to traditional large scale models. The analysis coincides with the experiment well and provides references for the transmission tower design.

Abstract: In this paper, the use of overhead ground wires as tension line of bearing cable .Using ANSYS and ADAMAS software ,To establish the dynamic model of power transmission line tension stringing,Considering the force of tension stringing process overhead bearing cable of ground wire. The study of tension stringing of transmission line show that the overhead ground wire as bearing cable of ground wire can meet the requirements of the tension line.

Abstract: In order to study the mechanical properties of the angle variable cross-section transmission tower against the corner of a 500kV transmission line tower, it becomes a node by node plate tower slope at a single angle and dual angle connected to a total of ten bars, dozens of bolts. The entire tower was built finite element model, the model is modal analysis, the results of the analysis of compliance with regulatory requirements. In the most unfavorable conditions, the tower each node variable slope rod internal forces are extracted, come times of stress accounted main material angle of principal stress ratio is large, need to be considered in the design.

Abstract: In order to study the residual fatigue life of 500 kv transmission tower under load conditions, a multi-scale finite element model of transmission tower is established. By simulating time course of wind load, using Miner fatigue cumulative damage theory and linear S-N curve, the calculation method of transmission towers fatigue life is established. The research shows that the multi-scale model can better simulate the stress and strain state of the transmission tower, and can predict the remaining service life of the transmission tower .The research has important significance and application value for the safe operation of the transmission lines.

Abstract: Compared with normal transmission towers, the multiple-circuit tower was higher and heavier,it also had a longer crossarm. Response spectral method was taken to analysis the transmission tower-line’s response under earthquake.The results obtained from single tower and tower-line system under the earthquake were compared with each other，such as the tower members’ axial stresses and horizontal shears on supports .In addition,this paper discussed seismic load effects on the transmission tower-line system and some useful results were derived.

Abstract: This paper analyzes a fractured lightning rod on a tower structure at a 500kV substation. By examining the residues of the rods, and utilizing simulation test and finite element analysis, the causes for this incident are discussed in detail, and a technical rationale is provided for preventative measures of incidents of this type.