УДК 621.315.177

Increasing the load-bearing capacity of overhead line structures

Научный руководитель Артамонова Екатерина Валерьевна – кандидат технических наук, доцент Казанского государственного энергетического университета.

Алиуллов Ильсур Ринатович – студент Института теплоэнергетики.

Abstract: Increasing the load-bearing capacity of overhead power transmission line structures is an urgent and important task of modern energy. With the constant increase in energy load and reliability requirements, it is necessary to develop new methods and technologies capable of providing higher stability and strength of such structures. One of the key factors in increasing the bearing capacity of structures is the optimal use of materials and the latest technical solutions. The use of reinforced racks and reinforced wires, as well as the use of composite materials, can significantly improve the bearing characteristics of structures. An important role is also played by the analysis and calculation of loads that occur on overhead power lines. Careful modeling and calculations using modern software tools make it possible to predict and analyze the behavior of structures under various conditions.

In addition, improving the methods of mounting and fastening structures can significantly increase their load-bearing capacity. The use of innovative technologies and modern equipment allows for more reliable and durable connections between structural elements. Thus, the paper describes an increase in the load-bearing capacity of overhead power transmission line structures, which requires an integrated approach, including the development of new materials and technologies, accurate calculations and analyses, as well as improving installation and fastening methods. This will make it possible to create more reliable and efficient power transmission systems that can work effectively in the face of modern energy challenges.

Аннотация: Повышение несущей способности конструкций воздушных линий электропередачи является актуальной и важной задачей современной энергетики. С постоянным увеличением энергетической нагрузки и требований к надежности, необходимо развивать новые методы и технологии, способные обеспечить более высокую устойчивость и прочность таких конструкций. Одним из ключевых факторов в повышении несущей способности конструкций является оптимальное использование материалов и новейших технических решений. Применение усиленных стоек и армированных проводов, а также использование композитных материалов может позволить значительно улучшить несущие характеристики конструкций. Важную роль играет также анализ и расчет нагрузок, которые возникают на воздушных линиях электропередачи. Тщательное моделирование и расчеты с использованием современных программных средств позволяют предсказывать и анализировать поведение конструкций при различных условиях.

Кроме того, усовершенствование методов монтажа и крепления конструкций может значительно повысить их несущую способность. Применение инновационных технологий и современного оборудования позволяет обеспечить более надежные и прочные соединения между элементами конструкции.

Таким образом, в работе описано повышение несущей способности конструкций воздушных линий электропередачи, которое требует комплексного подхода, включающего разработку новых материалов и технологий, проведение точных расчетов и анализов, а также совершенствование методов монтажа и крепления. Это позволит создавать более надежные и эффективные системы электропередачи, способные эффективно работать в условиях современных энергетических вызовов.

Keywords: overhead power lines, bearing capacity of the structure, supports of power transmission lines, energy supply, loads, operating conditions.

Ключевые слова: воздушные линии электропередачи, несущая способность сооружения, опоры линий электропередачи, энергоснабжение, нагрузки, условия эксплуатации.

In [1], detailed models of the towers being tested are modeled, and failure analysis is performed for comparison with full-scale tests. Stability coefficients are introduced into a user-defined material model to take into account the effect of the element's loss of stability during the modeling process. Based on the results of full-scale tests and numerical simulations, segments located near the crossbars are more prone to failure; these segments require more attention during the design and maintenance process.

In comparison with American, Chinese and European standards, the Riks analysis method is effective for obtaining stability coefficients of elements with different flexibility coefficients; this result is also confirmed by experiments on axial compression of steel corners.

The maximum bearing capacity and the failure mode of the tower obtained from the numerical simulation results are very similar to the results of field tests. Developed FE models and a user-defined material model are reasonable for modeling the actual behavior of a power transmission pole subjected to various loads.

Full-scale tests provide a valuable database for the design of power transmission poles exposed to various loads (broken lines, wind and ice), and the proposed numerical method is an effective alternative for checking the structure of the structure. The proposed method can also be used to evaluate existing towers or other similar structures.

The article [2] describes several models for representing joint effects, and numerical predictions are compared with experimental results. The main conclusions of the study are as follows:

Numerical results without taking into account the effects of joint slippage are insufficient to predict displacements during tower rocking. However, numerical models that take into account the effects of slippage of both diagonal elements and joints of the main supports can predict tower displacements with acceptable engineering accuracy.

Accounting for joint slippage will significantly increase the predicted deformation of the tower, but will not affect the modes and sequence of its destruction.

The effect of joint slippage on the ultimate bearing capacity of the supports will be determined by the magnitude of the applied vertical load, as well as the load trajectories and the associated failure mode of the tower.

After the destruction caused by typhoon Mujigae, an inspection of the facility was carried out in [3], during which malfunctions of the suspension tower were identified. One typical support for crossing the river, a 220 kV overhead support, has been analyzed. A static nonlinear analysis of the loss of stability is proposed, the maximum power and vulnerable panels of the tower under study are determined with a statistical wind force. The critical bending point of each element, including the support element and the diagonal element in the tower body, is calculated according to three codes, and the calculated strength of the element. Bending is taken into account when performing dynamic analysis. The results are in good agreement with the results of the site survey. The conclusions are based on two numerical methods as follows:

Nonlinear analysis of tower structure can predict the vulnerable panels in a rapid and simple way, the ultimate capacity evaluation results are also acceptable. But the determination of vulnerable member needs to be checked using dynamic analysis.

Dynamic analysis should be adopted to predict the tower behavior more accurately under wind load, the vibration of transmission line is notable that it changed the load pattern applied to the tower structure, fragile members determined by dynamic analysis is different with the ones predicted by the static nonlinear analysis.

Diagonal members are conventionally designed as lateral bracing for the leg members, however, according to the dynamic analysis, diagonal member turns out to be the fragile member, emphasis should be laid on designing of diagonal members.

A new experimental large-scale test facility in [4] is considered, which allows testing continuous, longitudinally limited strips of reinforced concrete slabs subjected to imitation of accidental destruction of the central support and subsequent vertical load until complete collapse. The details of this test facility were explained, as well as measurements related to the behavior of the load during movement. Within the framework of this study, it was found that the development of a chain reaction associated with the formation of large displacements significantly increases the maximum load-bearing capacity.

In [5], a study was conducted on changes in the maximum bearing capacity of a tower structure after corrosion. For this purpose, software with the finite element method was used to analyze the mechanical properties of the tower structure over a long service life. The results show that the wind direction at an angle of 45° is a control condition, and the overall rigidity of the tower decreases with increasing corrosion time and increasing movement of the upper part of the tower, the movement of the upper part of the tower reaches 7% after 12 years of corrosion. The corrosion-sensitive elements of the tower were clearly identified, and their stress coefficients increased from 0.78, 0.79 and 0.83, respectively, to 0.97, 0.98 and 0.99 over 12 years of corrosion.

Using the methodology in the work [6] will allow utility companies to better plan maintenance, whether it is an inspection or repair itself, minimizing the risk of structural failures OHTLS and/or allowing you to reduce costs. In other words, the methodology improves the efficiency of electricity supply services, which is very important. This methodology has been developed to provide a broader and more comprehensive understanding of the likelihood of progressive corrosion in certain locations in order to develop a method for planning more detailed inspections, whether intrusive, based on maintenance, replacement or repair. In this case, the results were found satisfactory with a success rate of about 80%.

Literature

Tian L. et al. Full-scale tests and numerical simulations of failure mechanism of power transmission towers //International Journal of Structural Stability and Dynamics. 2018. No. 09. P. 1850109.
Jiang W. Q. et al. Accurate modeling of joint effects in lattice transmission towers //Engineering Structures. 2011. No. 5. P. 1817-1827.
Zhang J., Xie Q. Failure analysis of transmission tower subjected to strong wind load //Journal of Constructional Steel Research. P. 271-279.
Gouverneur D., Caspeele R., Taerwe L. Experimental investigation of the load–displacement behaviour under catenary action in a restrained reinforced concrete slab strip //Engineering structures. 2013. P. 1007-1016.
Lin R. et al. Bearing capacity analysis of transmission tower structure considering corrosion damage //Journal of Physics: Conference Series. – IOP Publishing, 2022. No. 1. P. 012052.
Braga E., Junqueira R. M. R. Methodology for planning tower leg foundations corrosion maintenance of overhead transmission lines based on GIS //IEEE Transactions on Power Delivery. 2016. No. 4. P. 1601-1608.