Tower Type Research Articles

Dynamic responses of thin-walled FRP-concrete-steel tubular wind turbine tower under horizontal impact loading: Experimental study and FE modelling

Thin-walled FRP-concrete-steel tubular towers (TW-FCSTs), composed of an outer FRP tube, an inner hollow steel tube, and an interlayer of concrete, represent a novel type of wind turbine tower with promising application prospects. Given their potential risks to potential vehicle or vessel collisions, this study investigates the dynamic responses of five cantilevered TW-FCSTs using a horizontal impact device. These TW-FCSTs possess significantly large void ratios (i.e., φ=0.73or0.82) and practical large column sizes (i.e., Dc = 300 mm, Hc = 1500 mm). The experimental programme of this paper investigates several key parameters, including FRP thickness, steel thickness, and void ratio of TW-FCSTs, as well as the velocity and numbers of impact loading. Experimental findings demonstrate the following insights: (1) cantilevered TW-FCSTs exhibit an overall flexural failure mode after the horizontal impact loading; (2) the increase in steel thickness or FRP thickness contributes to greater energy dissipation and reduced localized dent deformation; (3) the higher void ratio results in more pronounced localized dent deformation and less overall deformation in specimens; (4) the proportion of energy dissipation caused by localized dent deformation increased with impact velocity, signifying more severe localized dent deformation at higher impact velocities. The utilization of FE models in LS-DYNA effectively simulates the dynamic performance of cantilevered TW-FCSTs, offering reliable predictions. Parametric studies were conducted to analyze influences of impact mass, impact height, concrete strength, and steel yield strength.

Life cycle assessment of typical tower solar thermal power station in China

In light of the growing environmental awareness and the sustainable development consideration in energy policies, the environmental impacts of concentrating solar power (CSP) have attracted significant attention. Considering that the site selection of CSP stations and databases used for evaluation has an important impact on the environment, the objective of this study is to assess the impact of concentrating solar power tower (CSP-T) station with thermal storage devices in the geographical context of China from environmental perspective by the life cycle assessment (LCA) method. To achieve this goal and ensure the reliability of the research results, a 2 × 50 MW capacity, double tank solar nitrate energy storage, and 12-h energy storage time CSP-T station in Dunhuang, Gansu, was selected. In addition, its model was constructed using the eFootprint online platform, assessing the environmental impacts of the CSP-T station according to the cradle-to-grave system boundary. Moreover, the impact assessment was performed in terms of key metrics, such as energy payback time (EPT), carbon cost of electricity (CCOE), carbon flow analysis, and environmental benefits of energy conservation and emission reduction. The results showed that the production stage is the most significant source of environmental impact in the life cycle of the CSP-T station, with the condensing system and heat storage system contributing 50.17 % and 47.64 % respectively. It can be found that the EPT of the CSP-T station is estimated at 4.88 years, accounting for 16.25 % of the operation cycle of the thermal power station, and varies depending on the station's location. It can be reduced to 3.19 years in places such as North Africa with abundant light intensity. Furthermore, the CCOE of the CSP-T station is 0.04 kg CO2/kWh. Overall, CSP-T station has over 95 % environmental benefits for energy conservation and emission reduction for most indices compared to thermal power station. Although the Chemical Oxygen Demand (COD) index is slightly lower, it still reaches 82.67 %. To promote the ecological development of the CSP-T station in China, this study usually includes a brief comment or relevant improvement recommendations after each comparative analysis.

Some Common Fixed Point Results of Tower Mappings in (Pseudo)modular Metric Spaces

In this paper, we prove the existence and uniqueness of common fixed point of tower type contractive mappings in complete metric (pseudo)modular spaces involving the theoretic relation. However, the newly introduced contraction in this paper further characterize and includes in their full strength several existing results in metrical fixed point theory. Some nontrivial supportive examples were given to justify our result. Our results generalize, improve, and unify some existing results.

Design and experimental research of a new type of power transmission tower climbing robot

There are a series of problems in the maintenance of transmission towers. In this paper, based on the existing structure, a climbing robot that can be applied to the transmission tower is designed, and the reliability of the grasp is analyzed. Key parts are optimized with Ansys analysis software and planning for climbing gait is completed with Adams simulation software; Robot control system is designed based on hierarchical and decentralized control architecture and the paw position adjustment decisions are optimized, and the fuzzy control algorithm is used to realize the gait adjustment of the robot The experiment result shows, the robot can complete the task of climbing and crossing the obstacle of the steel surface of the tower angle.

Effective Bounds for Induced Size-Ramsey Numbers of Cycles

The induced size-Ramsey number r^indk(H)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hat{r}_\ ext {ind}^k(H)$$\\end{document} of a graph H is the smallest number of edges a (host) graph G can have such that for any k-coloring of its edges, there exists a monochromatic copy of H which is an induced subgraph of G. In 1995, in their seminal paper, Haxell, Kohayakawa and Łuczak showed that for cycles, these numbers are linear for any constant number of colours, i.e., r^indk(Cn)≤Cn\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hat{r}_\ ext {ind}^k(C_n)\\le Cn$$\\end{document} for some C=C(k)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$C=C(k)$$\\end{document}. The constant C comes from the use of the regularity lemma, and has a tower type dependence on k. In this paper we significantly improve these bounds, showing that r^indk(Cn)≤O(k102)n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hat{r}_\ ext {ind}^k(C_n)\\le O(k^{102})n$$\\end{document} when n is even, thus obtaining only a polynomial dependence of C on k. We also prove r^indk(Cn)≤eO(klogk)n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hat{r}_\ ext {ind}^k(C_n)\\le e^{O(k\\log k)}n$$\\end{document} for odd n, which almost matches the lower bound of eΩ(k)n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^{\\Omega (k)}n$$\\end{document}. Finally, we show that the ordinary (non-induced) size-Ramsey number satisfies r^k(Cn)=eO(k)n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hat{r}^k(C_n)=e^{O(k)}n$$\\end{document} for odd n. This substantially improves the best previous result of eO(k2)n\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$e^{O(k^2)}n$$\\end{document}, and is best possible, up to the implied constant in the exponent. To achieve our results, we present a new host graph construction which, roughly speaking, reduces our task to finding a cycle of approximate given length in a graph with local sparsity.

Performance prediction of a novel solar power tower system based on spectral beam splitting

Photovoltaic technology is currently the most widely used solar generation technology in engineering. The particular spectral response band of PV cells cannot convert all solar radiation into electricity. Meanwhile, some radiation will become heat, leading to an increase in cell temperature and a decrease in the conversion efficiency of photovoltaic cells. Spectral splitting technology is an effective technology to improve electrical generation efficiency and can achieve full spectrum utilization of solar energy. The current work involved (1) proposing a novel solar power tower comprehensive utilization system based on spectral splitting; (2) developing a spectral splitting thin film configuration by using the Needle method whose transmittance is higher than 90% against the band range of 510 nm-1, 020 nm; (3) setting up a spectral splitting PV panel whose cover glass is coated the developed film, and replacing the heliostat of SPT system by using such spectral splitting PV panels; (4) predicting the electrical power generation of the spectral splitting-based tower type concentrating solar power system. The results demonstrate that the power generation efficiency of the proposed system is 5.5% and 3.46% higher than PV power generation and SPT systems respectively.

On the design of deep learning-based control algorithms for visually guided UAVs engaged in power tower inspection tasks.

This paper focuses on the design of Convolution Neural Networks to visually guide an autonomous Unmanned Aerial Vehicle required to inspect power towers. The network is required to precisely segment images taken by a camera mounted on a UAV in order to allow a motion module to generate collision-free and inspection-relevant manoeuvres of the UAV along different types of towers. The images segmentation process is particularly challenging not only because of the different structures of the towers but also because of the enormous variability of the background, which can vary from the uniform blue of the sky to the multi-colour complexity of a rural, forest, or urban area. To be able to train networks that are robust enough to deal with the task variability, without incurring into a labour-intensive and costly annotation process of physical-world images, we have carried out a comparative study in which we evaluate the performances of networks trained either with synthetic images (i.e., the synthetic dataset), physical-world images (i.e., the physical-world dataset), or a combination of these two types of images (i.e., the hybrid dataset). The network used is an attention-based U-NET. The synthetic images are created using photogrammetry, to accurately model power towers, and simulated environments modelling a UAV during inspection of different power towers in different settings. Our findings reveal that the network trained on the hybrid dataset outperforms the networks trained with the synthetic and the physical-world image datasets. Most notably, the networks trained with the hybrid dataset demonstrates a superior performance on multiples evaluation metrics related to the image-segmentation task. This suggests that, the combination of synthetic and physical-world images represents the best trade-off to minimise the costs related to capturing and annotating physical-world images, and to maximise the task performances. Moreover, the results of our study demonstrate the potential of photogrammetry in creating effective training datasets to design networks to automate the precise movement of visually-guided UAVs.

Bayesian uncertainty quantification of modal parameters and RRF identification of transmission towers with limited measured vibration data

The resonant response factor (RRF) sensitive to modal parameters, including the damping ratio and frequency, is a critical parameter for wind-resistant design of extra high voltage (EHV) transmission towers, because it directly affects the calculation of the wind vibration coefficient. However, the research on operational modal analysis (OMA) of in-service EHV transmission towers is limited due to the high risk of field monitoring. Therefore, it is critical to determine the size of sufficient data samples or minimum monitoring duration for the OMA of a transmission tower. In this study, an investigation of uncertainty quantification in Bayesian OMA of EHV transmission towers with small data samples from the ambient dynamic test is carried out. The uncertainty of the resonant component factor for wind-resistance design is proposed and quantified, which could provide engineering designers with a reference for confidence levels. Firstly, a field test system is installed on a multipurpose EHV transmission tower with a closed-loop cat head and a pair of cross-arms, to gather the acceleration responses. Then, the OMA for the transmission tower is carried out by the fast Bayesian FFT (FBFFT) method to determine the modal parameters as well as the associated posterior uncertainty. The small sample analysis of OMA for the transmission tower is further performed to obtain sufficient data samples and minimum monitoring duration. Finally, the distribution of the RRF is presented with the different confidential levels. It is found that a sampling length of 600 s could fulfill the basic needs of accuracy in Bayesian OMA and the determination of RRF. The outcomes of this study may provide a reference for the wind-resistance design parameter selection of the similar type of transmission towers.

Experimental study on the aerodynamic characteristics of combined angle transmission tower subject to skew wind

The transmission towers served as crucial carriers in the process of power transmission. The combined angle transmission tower of dual-angle steel with cruciform section are relatively a novel type of angle tower, which is being more widely used in transmission lines. The studies on aerodynamic characteristics of combined angle tower in skewed wind are limited. In this paper, the wind tunnel tests are conducted to investigate the aerodynamic characteristics of the combined angle tower, and the high frequency force balance (HFFB) test is introduced to obtain the transverse and longitudinal forces on the tower using the direct force measurement (DFM) method. The drag coefficients and wind load-distribution factors of the combined angle tower are obtained from the wind tunnel tests, and the effects of interference and tower leg spacing on the wind loads of the tower legs are fully explored. It can be found that the aerodynamic coefficients and drag coefficients of the combined angle steel tower leg tend to decrease with the increase of interference members and it also decreases with the decrease of the tower leg spacing. The test wind load-distribution factors of the isolated leg are generally larger than those defined by seven typical codes (e.g., US, EU, Japanese, and Chinese codes) and significantly exceed the code-specified values under partial wind angles. The observations obtained from this study may provide helpful guidance on the wind-resistant design of this relatively novel type of combined angle tower.

Model development of bond graph based wind turbine

<span>Just recently, wind energy continues to be one of most important renewable energy resources, by cause of its production is ecologically friendly; for that reason, the technology built for the renewable energy production by way of wind turbines takes excessive challenges in the study. Due to several physical domains prevailing in wind turbine, namely aerodynamical, mechanical and electrical, the modeling of wind turbine is problematic; thus, modeling based on physical techniques has a superior reliability in these circumstances. One of these approaches is bond graph modeling that model system evolved from conservation law of both of mass and energy comprising in the structures. This study presents modeling the parts of bond graph-based wind turbine. Then, sub models are connected together to attain the entire model of wind turbine for simulation based on 20-Sim software. The proposed wind turbine is 2.5 kW of variable velocity wind turbine with three blades, gearbox, tower, and doubly-fed induction generator type. The effectiveness of bond graph modeling system on wind turbine has been proven in simulation results.</span>

Örgüt Kültürü ve Yeşil Uygulamaların İçselleştirilmesi: Yabancı Alt Kuruluşlarda Karşılaştırmalı Bir Araştırma

This study aims to reveal whether organizational culture has an impact on the internalization of green practices. In this respect, the aim of this study is to show how structural practices arising from organizational culture are reflected in environmental practices developing at the organizational level. In line with the research purpose, a multiple case analysis was conducted on 3 subsidiaries that invested in the context of Türkiye. Eight interviews were conducted by following a semi-structured interview form to collect data on what kind of organizational culture three companies have and to what extent green practices are internalized. Subsequently, the collected data has been subjected to content analysis and research findings were obtained in this way. It was observed that the companies included in the research had an Eiffel tower and/or family type organizational culture. In the Company 1, which has an Eiffel tower culture, it was observed that green practices were adopted at a low-medium level. While it was observed that green practices were internalized at a high level in the Company 2, which incorporated eiffel tower culture and family-type culture elements, it was observed that green practices were internalized at a low-medium level in the Company 3, which adopted the same type of organizational culture as Company 3. Although the research findings show that there is no identical pattern in the adoption of green practices and organizational culture, the findings also shed light on how the elements of organizational culture should be in the context of required or volunteerism in the internalization of green practices in organizations.

Analysis and Design of Transmission Tower using Staad-Pro

A transmission tower, also known as an electrical power tower or utility pole, is a tall structure used to support overhead power lines for the transmission of electrical energy. Transmission towers play a critical role in the reliable and efficient transmission of electricity from power generation plants to distribution networks and ultimately to consumers. This abstract provides an overview of transmission towers, including their purpose, types, components, and key considerations in their design and construction. Transmission towers are designed to withstand various environmental and loading conditions, such as wind, ice, and seismic forces while maintaining the integrity and stability of the overhead power lines. Different types of transmission towers, such as lattice towers, tubular towers, and pole towers, are used based on factors such as voltage level, span length, and terrain conditions. Analysis of this transmission tower is administered using STAAD PRO The present work describes the analysis and design of a transmission line tower of 31 meters in height and 220KV double circuit viz. various parameters. The components of a transmission tower typically include tower legs, cross-arms, insulators, and hardware for attaching conductors and ground wires

Analysis of Spatial Characteristics Contributing to Urban Cold Air Flow

To mitigate the urban heat island phenomenon at night, cool, fresh air can be introduced into the city to circulate and dissipate the heat absorbed during the day, thereby reducing high urban air temperatures. In other words, cold air flow (CAF) generated by mountainous and green areas should be introduced to as wide an area as possible within the city. To this end, it is necessary to first understand the characteristics of urban spatial factors that impact CAF, and to conduct concrete and quantitative analyses of how these urban spatial characteristics are contributing to air temperature reduction. In this study, the following are conducted: (1) an analysis of the relationship between cold air volume flux (CAVF) and the amount of air temperature reduction; (2) urban spatial categorization; (3) an analysis of the relationship between CAVF and the amount of air temperature reduction by urban spatial type; (4) a regression analysis between the amount of air temperature reduction and urban spatial characteristic factors that affect CAF; and finally, (5) the use of CAF to reduce urban air temperatures in urban planning and a design is proposed. Urban space was categorized into nine types using the results of the tertile analysis of CAVF and urban temperature reduction. It was determined that building height (BH) has a positive (+) influence on all urban spatial types, while building area ratio (BA) has a negative (−) effect. However, in the case of wall area index (WAI), the direction of influence varied depending on the development density; relatively low BA areas should focus on development that increases height to increase WAI, while relatively high BA areas should focus on development that reduces BA to reduce WAI by targeting development types closer to the tower type. And even in areas with similar development density, influence varies depending on the terrain elevation. Moreover, it is necessary to prepare improvement measures to increase the factors with CAF that positively influence air temperature reduction and decrease those with negative influence according to the characteristics of urban spatial types. Such results quantitatively and specifically confirmed the effects of spatial factors that affect CAF by urban spatial type on air temperature reduction. The results of this study can be used as useful information for the efficient use of CAF, a major element of urban ecosystem services.

Method for extracting the free vibration response of transmission tower

The analysis of the free vibration in transmission towers is aimed at better evaluating their health status. Due to the non-stationarity of the height of non-uniform wind-induced vibration, there is a sustained forced vibration response in the vibration signal of transmission towers. This will lead to a decrease in the stability of vibration characteristics, which brings great difficulty to transmission tower status identification. In order to solve this problem, this paper proposes a method for extracting the free vibration response of transmission towers. By using Void–Kalman filtering (VKF) and generalized demodulation transform (GDT) for modal frequency tracking and pseudo-peak elimination, the signal is maximally cleaned while retaining all modal information. In addition, this paper combines variational theory and time-frequency domain features to decompose all effective modal orders in the vibration response. This not only solves the errors that exist when GDT and VKF directly process the original signal, but also makes the extraction of frequency parameters of each modal orders more convenient. The effectiveness of this approach is demonstrated by extracting the free vibration response of a 110 kV cat-head type tower. And by comparing it with existing mainstream signal processing methods using the example of bolt loosening faults. The results show that the signal processed by this approach can more stably and accurately capture the fault characteristics, providing a new idea for the extraction of free vibration response in the field of transmission tower health monitoring.

A Comprehensive Study of Different Types of Cooling Towers

Abstract: Cooling towers are essential components in a wide range of industries and processes, designed to dissipate excess heat generated during various operations. The efficient cooling of water or other heat transfer fluids is crucial for maintaining the optimal performance of machinery and equipment. This project presents a comprehensive study of different types of cooling towers, aiming to provide a thorough understanding of their functions, applications, and advantages. The study begins with an introduction to the fundamental principles of cooling towers, emphasizing the importance of heat exchange in industrial processes. It then digs into the various types of cooling towers, which include natural draft cooling towers, mechanical draft cooling towers, and hybrid cooling towers. Additionally, this study addresses showcasing successful applications of different cooling tower types in industries such as power generation, chemical manufacturing, and HVAC systems. Ultimately, the comprehensive study of different cooling tower types presented in this paper aims to provide engineers, industrial professionals, and researchers with valuable insights into selecting the most appropriate cooling tower design according to their needs

Numerical simulation of atmospheric transmittance between heliostats and heat receiver in Tower-Type solar thermal power station

Based on the Simple Model for Atmospheric Transmission of Sunshine and meteorological observations, a simulation method for atmospheric transmittance between tower solar thermal power heliostats and heat receivers is developed. This method is verified by the vertical radiation observations in Tianjin, China. The results indicate remarkable differences between the simulated global horizontal irradiation (GHI) and the observations under different weather types, and the magnitude of the difference is mainly influenced by near-surface visibility and cloud cover. However, the ratios of the simulated GHI at the altitude of 40 m to that of 200 m are basically consistent with the observations, with deviations of less than 0.02 for more than 97 % of the moments, indicating this method is applicable to simulating the ratio of GHI at different heights. Results show a 20-m increase in altitude leads to an increase of 0.009 % in atmospheric transmittance within 200 m above the ground. Due to the influence of meteorology, the atmospheric transmittance shows obvious diurnal and seasonal variations. Assuming the vertical altitude of a heat receiver is 200 m and its horizontal distance from a heat receiver is 50 m, the average atmospheric transmittance between them is 94.72 %, and the transmittance drops to 76.49 % at the horizontal distance of 1000 m. This method estimates atmospheric transmittance between heliostats and heat receiver, and provides reference for the design of tower type solar thermal power station and the evaluation of the operation status.

Study of the influence of the parameters of modern grounding wires on the value of power losses in them for overhead power lines of 330-750 kV

Introduction. The problem of estimating power losses in grounding wires with built-in fiber optic cable for overhead power lines of voltage class 330-750 kV is relevant, while it is obvious that the amount of losses depends on the chosen brand of wire. Problem. In the article, an analysis of the influence of the parameters of grounding wires on the amount of losses that occur in them in the normal mode of operation of the overhead power lines is carried out. Goal. The purpose of the work is to determine the criterion for the selection of grounding wires with a built-in optical fiber cable under the condition of increasing the energy efficiency of electricity transmission. Methodology. To calculate power losses in grounding wires, the methods of electromagnetic field theory were used, while taking into account the location of phase conductors on various types of towers of operating 330-750 kV overhead power lines and the possible current load of such lines. Results. The paper analyzed the dependence of losses in the grounding wires of the overhead power lines on the ratio of its active and reactive resistances, determined in which range of this ratio the losses will be close to the maximum. It is shown that the amount of specific power losses in the grounding wires of 330-750 kV overhead power lines in its normal operating modes can range from 1.6 kW/km for the 750 kV lines to hundreds of W/km for the 330 kV power lines. Originality. For the first time, it is recommended to use grounding wires with built-in fiber optic cable with running active resistance in the range of no more than 0.25 Ohm/km, which will minimize power losses and increase the energy efficiency of the 330-750 kV overhead power lines. Practical value. The obtained results can be applied at the stage of designing new or modernizing existing overhead power lines in order to reduce losses and increase the energy efficiency of lines.

Failure mechanism of a Q690 steel tubular transmission Tower: Full-Scale experiment and numerical simulation

The failure mechanism of a Q690 steel tubular transmission tower is investigated through full-scale experiment. The tower is mainly subject to the influence of the wind and the loads from the transmission lines. The displacements and the strains of the key positions as well as the ultimate bearing capacity of the tower are thus obtained. The final collapse is induced by the buckling instability of the compressed main member of a tower leg. A finite element model is established, whose validity is verified by the experimental data. Then, the numerical model is used for further analysis on the structural responses of the tower. It is found that once plasticity occurs at a certain point on the main member, its lateral displacement would be much accelerated, thus amplifying the second-order effect thereof. The horizontal auxiliary members, connected to the bottom of the compressed main member, are initially under tension. While the deformation of the main member is aggravated, they gradually undergo the transition from tension to compression, constituting a lateral support to the main member. This support then enforces the plasticity to develop towards the middle section of the main member, resulting in the final failure at the same location as observed in the full-scale experiment. These findings are crucial for a progressive understanding of the failure mechanism of this type of high-strength steel tubular towers, and they have contributed to the optimization of the design method to prevent the collapse of transmission tower under similar circumstances.

Not your typical Tower of Sauron

Not your typical Tower of Sauron

Segmental instability failures in transmission line towers

This paper presents the results of the detailed studies conducted on premature failures of transmission line towers during full-scale testing. Configuration and proportioning of base width, hamper width, the height of each segment and selection of bracing patterns play a vital role in providing geometric stability to the tower. In the present study, three towers of different voltage clauses failed during testing, investigated and found that geometric instability caused the premature failure. In the case of a 500 kV tower with a rectangular configuration, the staggered bracing pattern continuously for multiple segments for about 20 m height without a diaphragm bracing in between caused geometric instability in the tower. Nonlinear FEA results of the tower modelled with diaphragm bracing showed that tower failure can be prevented by introducing diaphragm bracing at different heights. The 400 kV double circuit dead-end type tower with a 15 m height bottom segment and 161 kV suspension towers analysed based on the conventional static analysis ignoring geometric instability failed prematurely and FE analysis clearly shows the failure due to geometric instability. It is recommended to divide the single segment into two segments such that the included angle between the leg and primary bracing member can be increased, and thereby additional moments in the leg members are reduced by making the bracing member contribute to sharing the shear. The code recommended minimum included angle of 15° between the leg and primary bracing member is only a guiding parameter for the designers. Based on this study, it is recommended that the designers shall check the tower geometry for segmental / panel instability by modelling and nonlinear FE analysis of the tower with beam elements in place of conventional space truss elements.