Tower Structure Research Articles

Optimal design of corona ring in composite insulator considering the effects of tower structure, conductor, hardware and mutual phases

One of the key elements in lowering the electric field intensity (EFI) on the creepage distance of composite insulators is the usage of the corona ring and its ideal design. First, using the Finite Element Method (FEM) in the 3D COMSOL Multiphysics program, this paper investigated and calculated the changes in the EFI of the creepage distance of the 230-kV composite insulator with and without taking into account the effects of the corona ring, tower structure, conductor, hardware, and mutual phases. Next, the ideal goal function is chosen in order to minimize the insulator creepage distance's maximal EFI. Nelder-Mead (NM) and Bound Optimization by Quadratic Approximation (BOBYQA), two optimization techniques, are used for the best design of corona ring parameters on the 230 kV insulator. Finally, the diameter, thickness, and installation position of the ideal corona ring are determined using the suggested methodologies and different restrictions. The obtained results demonstrate that, in contrast to previous studies that have only focused on a few of the aforementioned constraints, taking into account the tower structure, conductor, hardware, and mutual phases will have a significant impact on the distribution of the EFI on the insulator creepage distance.

Deformations of a three-dimensional model of a trihedral double lattice rod tower

Introduction. The calculation of deformations of spatial structures, as a rule, is carried out numerically on the basis of the finite element method. With the development of computer mathematical systems for regular systems an opportunity to obtain analytical solutions appeared. Such solutions can be used as test ones to evaluate numerical solutions and for preliminary calculation of a structure at design stage. The task has been set to derive deformation dependences of a spatial truss under various loads from its size and number of panels.
 
 Materials and methods. The truss of the tower structure is statically determined. The calculation of force values in the bars is performed by cutting out nodes in a Maple symbolic mathematics system. The Maxwell – Mohr formula is used to determine the displacement of a node at the top of the frame, considering only the longitudinal deformations of the rods. From the generalization of a series of analytical solutions for trusses with consecutively increasing number of panels onto an arbitrary number of panels the sought formula is derived by the induction method.
 
 Results. An algorithm of derivation of formulas for the deflections of a building along two mutually perpendicular horizontal axes under the action of lateral uniformly distributed nodal loads is presented. Effort distribution patterns are obtained for the truss rods and analytical stress dependences of some rods on the number of panels are found. Linear asymptotics of the solutions for the number of panels and the points of extremum are found and computed.
 
 Conclusions. The considered model of the spatial statically determined tower truss allows deriving exact formulas for deformations under the action of various loads within the limits of the adopted model. It is possible to use derived formulas for a preliminary estimation of designed structure and to apply as test ones for numerical calculations. The extremum points and analytical expressions for asymptotes allow the derived formulas to be used for solving stiffness optimization problems of a structure.

Undrained cyclic loading behavior of stiff Eocene-to-Jurassic plastic, high-OCR clays

Assessing foundation response to cyclic loading is vital when designing transport infrastructure, such as road pavements and rail tracks, as well as offshore, port, and tall tower structures. While detailed guidance is available on characterizing many soil types’ cyclic behavior, relatively few studies have been reported on stiff, geologically aged, plastic clays. This paper addresses this gap in knowledge by reporting cyclic loading experiments on three natural stiff UK clays that were deposited and buried between the Jurassic Age and Eocene Epoch before geological unloading to their currently heavily over-consolidated states. High-quality samples taken at relatively shallow depths were reconsolidated to nominally in situ K0 stresses in triaxial and hollow cylinder apparatus before imposing cyclic loading. The completely stable, metastable, or unstable outcomes invoked by different levels of undrained cyclic loading are interpreted within a kinematic yielding framework that is compatible with monotonic control experiments’ outcomes. The cyclic limits marking the onset of significant changes in permanent strain accumulation, pore pressure development, and stress–strain hysteresis demonstrate that the weathered Gault clay offers the lowest cyclic resistance. The experiments show that energy considerations provide a promising way of evaluating undrained pore pressure generation and stiffness degradation. They also provide a basis for developing cyclic constitutive models and analysis procedures for cyclic foundation design in stiff, high-OCR, plastic clay strata.

Data set from shaking table tests of a slender MDOF structure with base-rocking mechanisms

Numerical models of seismic-resistant structures are typically validated by comparing numerically predicted key seismic response parameters to those obtained from benchmark shake table experiments. However, studies have shown that for structures rocking on rigid foundations, the seismic response can be unrepeatable in experiments and deterministically unpredictable by numerical models. Therefore, researchers have proposed to validate rigid rocking models using statistical approaches, yet no experimental study has examined whether the same observations apply to slender multi-degree-of-freedom (MDOF) free-rocking structures or controlled rocking structures with positive post-rocking stiffness and dedicated energy dissipation. This data paper describes the now publicly available data obtained from a series of 254 shaking table tests of a slender MDOF tower structure with two base-rocking mechanisms, which can be used to examine the predictability of the seismic response of an MDOF rocking structure and to statistically validate different approaches aiming to model tall and slender structures that utilize base-rocking mechanisms to mitigate the dynamic response due to higher-mode effects.

Integration of high-precision UAV laser scanning and terrestrial scanning measurements for determining the shape of a water tower

This study was aimed at integrating surveys from terrestrial laser scanning (TLS) and high-precision scanning performed by a drone (ULS) for a tower structure. This will allow a complete point cloud to be obtained for the entire object. Integrated measurements will eliminate gaps in the point cloud, characteristic of TLS or ULS separate measurements. Existing studies report ULS accuracy of a few cm, but the precision may be about 10 mm. Assuming that the ULS point cloud will be matched to the TLS cloud, which has higher accuracy, the high accuracy of the whole integrated model can be expected. The integration of the surveys was carried out for the water tower and a coherent model of the structure was obtained, with a mean merge error of 13 mm. Detailed comparative analyses were carried out in selected cross-sections, obtaining mostly a several-millimetre compliance of the results in the analysed categories.

Modeling and modal analysis of the structure of long-span transmission tower

The structure of the long-span transmission tower is a typical nonlinear structure with the characteristics of great height, large line span, heavy overall weight and flexible tower body. The current design code only analyzes the traditional tower types, but the analysis of the truss structure of transmission tower is limited. Aiming at improving the design defects of the structure of long-span transmission towers, this paper uses the finite element software APDL to build the three-dimensional finite element model of a long-span transmission tower, to carry out the modal finite element analysis as well as to extract the specific parameters of each modal finite element mode: Modality, Natural frequency of vibration, Periodicity. The results show that the natural vibration period of the main machinery of this type of steel transmission tower is about 0.37–1.37 s; The structure of the long-span transmission tower has certain displacements in six degrees of freedom, in which the value of the X-dimensional displacement is the largest. There are some large displacements and local torsion in the high-order mode, combined with the results of modal analysis, so it is suggested to consider the structural improvement or external reinforcement of the weak parts of the long-span transmission tower.

How to Fold a Triangle: The Connection between the Grashof Fourbar Linkage and Pythagorean Triangles

Summary This paper presents two different methods for folding a triangle onto a flat line by converting it into a Grashof Special Case fourbar linkage. Foldable triangles have many applications, ranging from space structures to collapsible furniture. In the first method, a generic triangle with positive real side lengths is shown to be foldable inward and outward by adding a pin joint at a specific location to one of the sides. The second method shows how to create a collapsible linkage using a Pythagorean triangle; we demonstrate that all four links in the Pythagorean fourbar have integer length and can be easily built using rods with uniformly spaced holes (e.g., LEGO bricks, Unistrut, etc.). Next, the formulas for finding the interior angles of the Pythagorean fourbar are presented, for the purpose of plotting collapsible structures with mathematical software. We conclude with a demonstration of a sample application of Pythagorean fourbars to collapsible arch or tower structures and a surprising proof that some types of collapsible arch structures are unrealizable with Pythagorean fourbars.

Coupled analysis of monopile offshore wind turbine under modified three-dimensional seafloor ground motions

The safe operation of offshore wind turbines (OWTs) is significantly influenced by the combined effect of wind, waves, and offshore earthquakes. However, limited seafloor ground motion data have been used to determine the dynamic characteristics and responses of OWTs subjected to offshore earthquakes. Hence, synthetic seafloor ground motions are particularly important for seismic analysis of OWTs. This paper proposes a new method to simulate seafloor ground motions. In the study, the dynamic shear modulus of the water-bearing soil layer and the damping effect of the soil–seawater layers were introduced to modify the simple Crouse and Quilter (C-Q) model in seawater and P-SV and SH transfer function models at offshore sites. Further, three-dimensional seismic waves were synthesized based on the modified transfer function models at a typical offshore site with bedrock–soil–seawater layers, and a fully coupled numerical analysis model of OWTs, including the rotor nacelle assembly, tower structure, and substructure with pile–soil interaction (PSI) under wind, wave, and seafloor ground motion, was established by incorporating the earthquake module and PSI module into the updated FAST v8 software. Moreover, based on the established coupled OWT model, the measured seafloor ground motion records and the seafloor ground motions synthesized using the proposed method were compared, and a coupled analysis of the OWT under wind, wave, and offshore earthquake loadings was carried out. Furthermore, the coupled mechanisms of the OWT under synthesized and recorded seafloor ground motions were determined.

Health monitoring of ultra high fiber performance reinforced concrete communication tower using machine learning algorithms

Within the last decades, the needed for communication towers has accelerated with the requirements for effective communication, especially for radio, radar, and television. The complexity configuration of the tower and limit access to the structure body especially inner part of the tower with hollow section is led the health monitoring of tower as the main challenging issue to maintenance during its function. The change of natural frequencies can be considered as one of the prevalent damage detection methods in structural assessment procedures. Therefore, the main aim of present research is to develop health monitoring system for Ultra High Fiber Performance Reinforced Concrete (UHPFRC) communication tower based on frequency domain response. Since the frequency data of tower is mostly noisy and interpreting of frequency in different modes in variant case of tower damage. The hybrid algorithm based on the Adaboost, Bagging and RUSBoost algorithms are implemented to identify the damage in the UHPFRC communication tower using frequency domain data. The training samples for the algorithm are obtained from a finite element simulation and full-scale experiment testing is also performed to generate the testing samples. The finite element simulation dynamic frequency results are verified through conducting a full-scale experimental test on 30 m height UHPFRC communication tower. For this propose, frequency Response Functions (FRF’s), for healthy and damaged structures were obtained by exciting of tower by an impact hammer and the acceleration response recorded by three accelerometers sensors attached in suitable positions. The developed hybrid algorithm to identifying the damage is tested and verified by considering the part of tower segments 2–3 and conducting experimental testing on the healthy structure as well as a damaged structure which caused using dynamic actuator. The testing results proved the accuracy of the developed optimized hybrid algorithm to identify damage in the tower structure in variant condition.

Predicting the seismic behavior of multiblock tower structures using the level set discrete element method

AbstractIn this paper a modeling method is validated at multiple scales for the seismic performance of multiblock tower structure (MTS). MTS are a proposed concept for large‐capacity gravitational energy storage that will enable renewable energy sources. The structure modeled is a tower of 7144 nominally identical blocks arranged in a 38‐layered annular pattern with no adhesive mechanisms between the blocks or the blocks and the foundation. The level set discrete element method is used to model the dynamics of the tower structure experiencing a ground motion. Experimental determination of each model parameter is shown from the use of individual blocks before construction. Close comparisons to experimental results are shown for the dynamic motion of the tower over a full ground motion time history for multiple scales, materials and ground motions. When the tower was brought to failure, the two ground motions used produced distinct failure modes of the tower showing both a peeling and buckling behavior. Both the effect of the friction coefficient and unequal block heights are investigated. Friction coefficient has a noticeable effect on the amplitude of motion of the tower while the unevenness of the block heights affects mostly the structural speed.

Machine Learning-Based Prediction of Dynamic Responses of a Tower Crane under Strong Coastal Winds

With the rapid development of the construction industry, tower cranes are increasingly used in coastal engineering. However, due to the complexity of their operating environment, tower cranes are vulnerable to typhoons, thunderstorms, and other extreme natural disasters. Therefore, it is becoming increasingly important to carry out safety warnings for the tower crane structure under the action of strong winds. In this paper, a real-time monitoring system for tower responses based on the Internet of things (IoT), which realizes long-term monitoring of the whole process of tower crane operation, was built. Based on the long-term monitoring data and the machine learning algorithm, two tower response prediction models were established. During the transit of super typhoon In-fa, the maximum displacement of the tower structure was predicted in advance, based on the measured wind speed data at the site, which is in good agreement with the displacement data monitored by the IoT. The results show that under strong winds, the non-working tower has a response lag, resulting in the fact that its maximum displacement does not correspond to the maximum wind speed moment at the site. This is mainly due to the weathercock effect of the tower in the non-working condition. The prediction model proposed in this paper can provide timely and effective safety warnings for the tower structure. It also can provide useful engineering references and scientific structural safety warning suggestions for the same type of tower cranes that do not have IoT monitoring systems installed.

ON THE PROBLEM OF CLASSIFICATION OF BATTLE TOWERS 
 OF INGUSHETIA

The relevance of the problem under consideration, in addition to its epistemological interest, is also due to its practical significance. A large number of medieval archaeological and historical monuments of mountainous Ingushetia are disappearing, being destroyed before our eyes, and are in a dilapidated state. The state, having declared these objects of cultural heritage of the Ingush as its property, cares little about their preservation, practically does not allocate funds for their conservation and, moreover, restoration. Local teip communities are invited to finance these works themselves. However, even isolated cases of restoration work at the expense of sponsors cause a lot of disputes and questions. In particular, one of such pressing issues is the question of the restoration of combat towers according to one or another of their type, since they differ in their structural details, especially in their roofing part, which is most susceptible to destruction. Such controversial situations arose, for example, during the recent restoration of combat towers in the villages of Harp and Bisht of the Jeyrakh district of the Republic of Ingushetia. This problematic situation seems to be based on the imperfection of the existing classifications of Ingush combat towers.The purpose of the article is a critical analysis of the basic principles (bases) of the classification of combat towers and an assessment of their suitability for the reconstruction of the appearance of the latter. To achieve this goal, it is supposed to analyze and compare the classifications available in the literature (including types and types of combat towers and their distinctive features), identify their weaknesses and strengths, as well as assess the suitability of existing classifications as a possible scientific and theoretical basis for the restoration of Ingush combat towers.As a methodological basis for the research, this article uses a comparative analysis of the main classifications of Ingush combat towers, identification of possible classification principles and their assessment with the so-called suitability for the purposes of reconstruction of the appearance of the roofs of combat towers, as well as content analysis of the literary register of medieval tower structures of Ingushetia.

ON THE PROBLEM OF CLASSIFICATION OF BATTLE TOWERS 
 OF INGUSHETIA

The relevance of the problem under consideration, in addition to its epistemological interest, is also due to its practical significance. A large number of medieval archaeological and historical monuments of mountainous Ingushetia are disappearing, being destroyed before our eyes, and are in a dilapidated state. The state, having declared these objects of cultural heritage of the Ingush as its property, cares little about their preservation, practically does not allocate funds for their conservation and, moreover, restoration. Local teip communities are invited to finance these works themselves. However, even isolated cases of restoration work at the expense of sponsors cause a lot of disputes and questions. In particular, one of such pressing issues is the question of the restoration of combat towers according to one or another of their type, since they differ in their structural details, especially in their roofing part, which is most susceptible to destruction. Such controversial situations arose, for example, during the recent restoration of combat towers in the villages of Harp and Bisht of the Jeyrakh district of the Republic of Ingushetia. This problematic situation seems to be based on the imperfection of the existing classifications of Ingush combat towers.The purpose of the article is a critical analysis of the basic principles (bases) of the classification of combat towers and an assessment of their suitability for the reconstruction of the appearance of the latter. To achieve this goal, it is supposed to analyze and compare the classifications available in the literature (including types and types of combat towers and their distinctive features), identify their weaknesses and strengths, as well as assess the suitability of existing classifications as a possible scientific and theoretical basis for the restoration of Ingush combat towers.As a methodological basis for the research, this article uses a comparative analysis of the main classifications of Ingush combat towers, identification of possible classification principles and their assessment with the so-called suitability for the purposes of reconstruction of the appearance of the roofs of combat towers, as well as content analysis of the literary register of medieval tower structures of Ingushetia.

Directionally tailoring micro-nano hierarchical tower structured Mn0.6Ni1.4Co2Oy toward solar interfacial evaporation

Solar interfacial evaporation has been considered as a promising method to alleviate fresh water resources shortage. The shortage of freshwater resources requires advanced materials that can accelerate the evaporation of water by the sun. However, the simple structure of photothermal materials are vitally restricted by finite light absorption. Herein, this work presents a strategy for the synthesis of a spinel-type micro-nano hierarchical tower structure solar absorbent (Mn0.6Ni1.4Co2Oy) with the low forbidden band (=1.56 eV) and high absorption (97.88%). The products show great potential in solar-thermal energy conversion by creating a trapping effect. The prepared solar absorbent and epoxy resin are evenly mixed and then fully immersed in polyurethane (PU) sponge for water evaporation. The hydrophilic and porous Mn0.6Ni1.4Co2Oy @PU sponge can quickly deliver water upwards, suppress the heat loss, and concentrate the absorbed heat on the evaporation of water. The products exhibited an excellent evaporation rate of 2.261 kg m−2 h−1 and an impressive evaporation efficiency of 156% under a single sun exposure. Besides, the samples also can maintain the stability and recycling performance for a long time. These findings show that Mn0.6Ni1.4Co2Oy have great application prospects in the solar interfacial evaporation.

Comparative analysis of transmission line towers for angle section and square hollow section structural configuration in Indian context

With increase in the electric energy consumption, there has always been a need to reduce cost required to produce as well as transport it with least impact on the environment, the prime method of transferring the electric power being Transmission Line Towers. The most common and majorly dominating structural configuration used for Transmission Line Towers in Indian region is Angle Sections. This study is an attempt to introduce a new section configuration: Square Hollow Sections, having a notable impact in properties of Transmission Line Towers positively in comparison with the angle – section Transmission Line Towers. The guidelines for calculating member capacity of an Angle – section Transmission Line Towers is stated in Indian Standard Codal Provision, IS 802: 1995 (Part 1), Section 2. However, since there is no provision laid for the determination of same in case of a Square Hollow Section, IS 800: 2007 is used to determine the capacity of a Square Hollow Section – Transmission Line Towers. For carrying out the comparative study, a Twin – Conductor Tower is taken into consideration, located in Wind Zone V as per Indian Context. While conducting the analysis, all the other parameters remained constant, other than the legs of the structural configuration of transmission towers as they contribute a major impact in the overall properties of the towers. The analytical tool used for carrying out the analysis is STAAD Pro. Connect Edition. The loading conditions on the towers are applied as per the provisions laid in IS 802: 1995 (Part 1). The study yields that with an increase in Rv values of square hollow section, the overall redundancy of the tower structure had been reduced, thereby reducing the area of the application of wind loads on the structure, making the same an optimized solution for a comparative less – weight, economical with same power transmission, tower structural configuration.

Lightning Flashover Characteristics of a Full-Scale AC 500 kV Transmission Tower with Composite Cross Arms

Overhead transmission lines (OTLs) have always been the major means of power delivery. With the significant increase of transmission voltage and transmission capacity, the dimensions of transmission towers are increasing accordingly, resulting in extensive occupation of land resources. Towers with composite cross arms are a promising solution to this problem, considering the remarkable performance of composite line insulators. In this research, a full-scale alternating current (AC) 500 kV model of a transmission tower with composite cross arms is manufactured and applied under a lightning overvoltage of different polarities. The developing process of streamer-leader discharge is recorded with a high-speed camera, and the major path of the flashover is identified. The flashover voltages are measured and corrected to standard conditions while considering the air humidity and air density, and clearly confirm the polarity effect. The tower’s lightning-withstand level is calculated based on the tower structure and the flashover characteristics. Based on the results obtained from full-scale experiments, the feasibility of composite cross arms is confirmed, and a structural optimization is proposed.

Analysis of the Influence of UNMANNED Aerial Vehicles Stationed in Tower Airport on Tower Structure Safety

In order to solve the problems of uav inspection, such as limited endurance and difficulties in long-distance communication and control, it is proposed to set a steel structure platform on the tower as the airport of UAV. The installation of the tower airport will increase the permanent load and generate additional wind load, which may adversely affect the tower. In this paper, the tower of 220kV overhead transmission line is taken as an example to establish the finite element models of uav platforms at different positions of the tower and with different tower types. Considering the load effect of the tower and the platform, the maximum displacement and maximum stress of the initial model of the tower and the model after the installation of the platform are summarized and analyzed. The results show that the uav platform under the tower body has little influence on the safety performance of the tower, meets the safety operation requirements of the tower, and provides a new idea for the intelligent inspection of the transmission line uav.

Material Selection Analysis of UHV AC Double Circuit Steel Pipe Tower Cross Arm Structure

The cross arm of wire is an important part of the UHV tower, and the force and calculated length of the upper and lower main or inclined materials are smaller than the main or inclined materials of the tower, and the two types of section types, Angle steel, and steel pipe, have their own advantages and disadvantages. How to select materials reasonably and give full play to their advantages is an important content of the optimization design of the tower structure. In this paper, the double circuit steel pipe tower of the same UHV project tower is taken as an example, and the main material of the cross arm and the inclined material are selected Angle steel or steel pipe. The research shows that the main material of the cross arm is Angle steel, the main material of the cross arm is suggested to be steel pipe, the front inclined material of the cross arm is steel pipe, and the material selection principle of the cross arm can provide a reference for the future engineering design.

Influence of phase sequence arrangement on the electromagnetic environment of four-circuit AC line on the same tower

The paper predicts the power frequency electric field (PFEF), audible noise (AN), and radio interference (RI) of double-circuit 220kV and double-circuit 110kV four-circuit lines on the same tower erected on the same tower through the numerical calculation method of electromagnetic environment (EME) of AC transmission lines (TLs). Through a typical tower structure, the influence of the phase sequence (PS) on the EME is analysed, and the optimal and worst PSs are obtained. The optimal PS can significantly improve the EME, especially with a good confinement effect on the electric field’s power frequency. In addition, it also focuses on analyzing the influence degree of PS when the phase spacing, conductor-to-ground height and layer spacing change and establishes the applicable range of the optimal PS.

Finite Element Simulation and Experiment of Temporary Active Transverse Brace of Inward-inclined Bridge Tower Construction

For the bridge tower with large inclination angle, the beam element in Midas finite element software is used to model and analyze the bridge tower structure, and its accuracy is difficult to guarantee. In this paper, taking the construction of a suspension bridge’s inward-inclined tower as the research background, the finite element simulation of the inward-inclined bridge tower is carried out by using the two modeling methods of the beam element and the solid element. The calculation accuracy of the beam element model, the specific position and the jacking force applied by the active transverse brace of the inward-inclined bridge tower are determined, and the field test of the tower bottom stress during the construction process is performed. The results show that: when the inclination angle of the bridge tower is small (5 °), the beam element element is used for modeling and analysis, which has fast calculation speed and high calculation accuracy; When the inclination angle is 15 °, the error of the beam element model exceeds 30%, and it is recommended to use the solid model for calculation; the active cross brace plays a key role in controlling the stress at the bottom of the tower column before the lower cross beam is applied. And after the construction of the cross beam, the active cross brace forms a closed frame structure with the lower tower column, and the subsequent cross brace has little impact on the stress at the bottom of the tower column; Compared with increasing the number of temporary cross braces, increasing the jacking force can improve the stress at the bottom of the tower. And by adjusting the position of the active cross brace and applying the appropriate active jacking force, the stress at the root of the tower column can be greatly improved.