Television Tower Research Articles

Determination of the stress-strain state of models of steel cylindrical tanks using the “ANSYS” program

In the world, metal cylindrical shell constructions occupy a leading position in the construction of reservoirs for various purposes, bodies of water pressure generating towers, television towers, chimneys, lighting masts, tower cranes and similar engineering structures. In this direction, in developed countries such as the USA, Germany, Japan, and Russia, special attention is paid to increasing the load-carrying capacity of cylindrical shell structures, ensuring earthquake resistance and priority, reducing metal consumption, preventing the resulting deformations, and thereby ensuring their reliable operation. In this regard, one of the important tasks is to increase the priority of various construction structures, optimize their shape and size, improve existing calculation methods, and develop modern advanced methods of construction preparation and assembly.

CFD wind tunnel investigation for wind loads of steel television tower with grid structure

Television(TV) towers with grid structures serve as broadcasting frequency modulation or television transmission signals and provide sightseeing opportunities. Accurate wind load information is critical to the design of these towers to ensure their resistance to wind. Due to the scaling ratio of the test model, wind tunnel test can only determine the overall wind load, resulting in the loss of wind load information on specific rods. However, there is currently a lack of research on the wind loads of the specific rods of a core tube with a grid structure. This article focuses on this special topic. Computational fluid dynamics (CFD) technology, which was validated based on the Commonwealth Advisory Aeronautical Research Council (CAARC) model, was employed in simulation for a towering television tower with a grid structure. Wind load distributions of the grid structure and core tube were studied, including flow streamlines, velocity profiles and wind pressure distributions. The results indicate that the wind pressure distribution on the outer surface of the cross rods is similar at different heights. Net wind pressures of the rods in the flow separation zone are close to 0, which significantly reduces the across-wind load. Different wind direction angles significantly influence the wind load of the grid structure but slightly influence the core tube. The simulation results can provide a reference for wind load design of similar grid structures.

Evaluation of the stability of a two degrees-of-freedom dynamical system

This work studies a two degrees-of-freedom (DOF) dynamical system whose governing system is solved analytically using the multiple scales approach (MSA). The solvability requirements are obtained in light of the elimination of secular terms. All resonance states are classified to understand the equilibrium of the dynamical system. Two of them are examined in parallel to get the associated equations for the system’s modulation. All probable fixed points are identified at the states of stability and instability using the criteria of Routh-Hurwitz (RH). The curves of resonance and the system’s behavior during the motion are plotted and analyzed. The numerical solutions (NS) of the governing system are obtained using the method of Runge-Kutta fourth-order, and they are compared with the analytical solutions (AS). The comparison reveals high consistency between them and proves the accuracy of the MSA. To determine the positive effects of different parameters on the motion, stability zones are studied from the perspective of their graphs. The applications of such works are very important in our daily lives and were the reason for the development of several things, including protection from earthquakes, car shock absorbers, structure vibration, human walking, television towers, high buildings, and antennas.

Comparative evaluation of implementation options for partial radiators for antenna systems of urban radio centers under severe restrictions on placement conditions

In connection with the active development of urban infrastructure and the expansion of residential areas, it becomes necessary to provide corporate mobile radio communications with a large coverage area. In this regard, a number of problems arise, since in most cases special television towers and cellular communication masts are already occupied, and the location on high-rise buildings that are not adapted for antenna placement has rather severe restrictions. Calculation and study of the characteristics of PIFA type antennas placed on high-rise buildings under severe restrictions on placement conditions. Results. The results of calculations of antennas of the PIFA type are obtained, taking into account the environment. A technical solution for a dual-band PIFA VHF antenna is proposed. It is shown that with duplex operation isolation of at least 20 dBm, VSWR of no more than 2 with a bandwidth of 3 MHz is achieved.

Strength characteristics of load-bearing reinforced concrete structures of the Ostankino television tower

The article describes the design features of the Ostankino TV tower in Moscow. The main results of the earlier works of the load-bearing reinforced concrete structures of the TV tower column and foundations are presented in the article. The authors examined the internal and external surfaces of reinforced concrete structures of the entire height of the tower with selective defectoscopy and determined the actual strength of concrete by non-destructive methods. The figures of this work show the main structural reinforced concrete elements and a distribution graph of strength characteristics of the height of the structure. Despite the noticeable height changes, the concrete strength in all parts exceeds the value provided for in the project.

A Review of Complex Geometric High Rise Buildings According to TBDY 2018: The Case of Çamlıca Hill TV and Radio Tower

Deprem yönetmelikleri, yapıların deprem etkisi altında performanslarının değerlendirilmesi ve güçlendirilmesi için belirlenmiş kurallardır. Bu kurallardan yoksun tasarlanan yapıların dayanımlarının ne derece güçlü oldukları tartışma konusudur. Yanal yükler altında hassas davranışlar sergileyen yüksek yapılar bu bağlamda ön plana çıkmaktadır. Özellikle organik formlara sahip ya da fraktal geometrilerden türetilmiş olan (kompleks geometrili) yüksek yapılar için bu durum daha fazla dikkat edilmesi gereken bir konudur. Türkiye’de deprem yönetmeliklerine bakıldığında yüksek yapılara özel kuralların 2018 yılına kadar yönetmeliklerde bulunmadığı görülmektedir. Buna rağmen ülkemizde 2010 yılından itibaren 50 kat ve üzerinde farklı geometrilerde birçok yüksek yapının inşa edildiği görülmektedir. Üstelik bu yapıların çoğu deprem riski bölgelerinden birisi olan İstanbul’da bulunmaktadır. Bu nedenle bu çalışmada 2018 yılı öncesi inşasına başlanmış olan kompleks geometrili İstanbul Küçük Çamlıca Tepesi TV ve Radyo Kulesi örnek alınarak TBDY’nin 2018’de eklenen yeni kuralları ve sağlık izleme sistemi yönergesi üzerinden incelemeleri yapılmıştır. Bu değerlendirme aşamasında ilk olarak TBDY2018’den alınan düzensizlik tanımlarının hangi faktörler sonucu meydana gelebileceği ve buna karşı hangi önlemlerin alınabileceği sunulmuştur. Daha sonra bu faktörlerin örnek yapı üzerinde var olup olmadığı tespit edilerek, yapının mevcut yönetmeliğe uygunluğu tartışılmıştır. Kurallar ile uyumsuz olan uygulama tercihlerinde ise düzensizliklere karşı önlem alınıp alınmadığı incelenmiştir. İkinci etapta yönetmelik gereğince yüksek yapılarda şart koşulan yapı sağlığı izleme sisteminin yönerge kapsamı sunularak hangi maddeler ile yüksek yapıların incelenmesi gerektiği ortaya konmuştur. Daha sonra Çamlıca Tepesi TV ve Radyo Kulesi üzerinden bu kurallar doğrultusunda nasıl yaklaşım gösterilmesi gerektiğine dair örnek bir değerlendirme yapılmıştır. Yapılan değerlendirmelerde 2018 yönetmeliğine yeni eklenen sağlık izleme sistemi yönergesi kurallarının kompleks geometrili yapılar için hayati önem taşıdığı ve rüzgâr unsurunun yönetmeliklerde yeteri düzeyde bulundurulmadığı sonucuna varılmıştır. Bu çalışmanın amacı; mimari tasarım ve yönetmelik kavramlarının uyumsuz düştüğü noktalara örnekler vererek rijit ve estetik değere sahip yapı tasarımları için farkındalık yaratmak ve sağlık izleme sisteminin tasarımda bir faktör olarak değerlendirilmesini teşvik ederek literatüre katkı sağlamaktır.

Structural dynamic response reconstruction using self-attention enhanced generative adversarial networks

In structural health monitoring (SHM) of civil engineering structures, loss of measured structural responses inevitably occurs in practice, especially when structures encounter extreme loads. The loss of measurements severely undermines the completeness of the collected structural information and the reliability of structural condition assessment. Therefore, timely and accurate recovery of lost data is of paramount importance. This paper proposes a novel approach based on a self-attention mechanism enhanced generative adversarial network (SAGAN) for learning the intrinsic correlations between responses and reconstructing the lost data based on the accurately measured ones. SAGAN innovatively embeds the self-attention mechanism in the computational flow to facilitate the extraction of spatial and even temporal correlations among structural responses. In the experimental validations, the reconstructed responses of Guangzhou New Television Tower (GNTT) show great agreement with the true responses in forms of both time sequences and Fourier spectra. SAGAN is also versatile, demonstrating its effectiveness and robustness by reconstructing the responses competently under both ambient and typhoon excitations. In addition, by visualizing and analyzing the internal matrices and feature maps of SAGAN, it is found that the self-attention module benefits the learning of data features and improves the establishment of mappings between responses. The suitability of the proposed approach for SHM related tasks is validated by extremely consistent modal parameters. The identified natural frequencies from the reconstructed and the corresponding true responses are identical, and the Coordinate Modal Assurance Criterion (COMAC) value reaches to 99.98%.

Modeling and analyzing the motion of a 2DOF dynamical tuned absorber system close to resonance

This work investigates the planar motion of a dynamical model with two degrees-of-freedom (DOF) consisting of a connected tuned absorber with a simple pendulum. It is taken into account that the pendulum’s pivot moves in a Lissajous trajectory with stationary angular velocity in the presence of a harmonic excitation moment. In terms of the model’s generalized coordinates, Lagrange’s equations are used to derive the motion’s controlling system. The approximate solutions of this system, up to a higher order of approximation, are achieved utilizing the approach of multiple scales (AMS). Resonance cases are all classified, in which two of them are examined simultaneously to gain the corresponding equations of modulation. The solutions at the steady-state are studied in terms of solvability conditions. According to the Routh-Hurwitz criteria, all potential fixed points at steady and unsteady states are determined and graphed. The dynamical behavior of the motion's time-histories and the curves of resonance are drawn. Regions of stability are examined by inspecting their graphs in order to assess the favorable impact of various parameters on the motion. The achieved outcomes are regarded as novel because the used methodology is applied to a specific dynamical system. The importance of this model under study can be seen from its numerous applications in disciplines like engineering and physics. Furthermore, pendulum vibration absorbers are commonly employed to reduce the vibrations in engineering constructions such as chimneys, bridges, television towers, high buildings, auto-balancing shafts, and antennas.

Research on Wind Load Characteristics on the Surface of a Towering Precast Television Tower with a Grid Structure Based on Large Eddy Simulation

Local wind pressures on tiny rods of complex grid structures are difficult to obtain through wind tunnel tests due to their small sizes after scaling down, resulting in a lack of data support in wind load calculations for similar structures. However, local wind pressures on tiny rods can be obtained through numerical wind tunnel simulation using full-sized models. In order to investigate the wind pressure distribution of a grid structure and the influence of grid structures on the wind load of core tubes, three different television tower models are established based on an engineering example for large eddy simulations. A turbulence inlet generator (NSRFG) is adopted in the simulations while reproducing a portion of the wind tunnel test section including the mean and fluctuating pressures for validation. The results indicate that the mean wind pressures on the intersection of rods in the windward zone of the grid structure are higher than those on adjacent rods. Distinct reductions in the mean and fluctuating wind pressure of the grid structure are found in different zones. Moreover, resultant wind load forces and bending moments in the X and Y direction of the grid structure generally exceed 70% of the total wind loads. Based on simulation results, extreme net wind pressures of the grid structure and shape coefficients of enclosed regular octagonal cross-section buildings with the grid structure are provided for reference.

Influence of loading sequence on wind induced fatigue assessment of bolts in TV-tower connection block

Bolted connections are widely employed in structures like transmission poles, wind turbines, and television (TV) towers. The behaviour of bolted connections is often complex and plays a significant role in the overall dynamic characteristics of the structure. The goal of this work is to conduct a fatigue lifecycle assessment of such a bolted connection block of a 193 m tall TV tower, for which 205 days of real measurement data have been obtained from the installed monitoring devices. Based on the recorded data, the best-fit stochastic wind distribution for 50 years, the decisive wind action, and the locations to carry out the fatigue analysis have been decided. A 3D beam model of the entire tower is developed to extract the nodal forces corresponding to the connection block location under various mean wind speeds, which is later coupled with a detailed complex finite element model of the connection block, with over three million degrees of freedom, for acquiring stress histories on some pre-selected bolts. The random stress histories are analysed using the rainflow counting algorithm (RCA) and the damage is estimated using Palmgren-Miner's damage accumulation law. A modification is proposed to integrate the loading sequence effect into the RCA, which otherwise is ignored, and the differences between the two RCAs are investigated in terms of the accumulated damage.

Wind Load and Wind Vibration Response of a TV Tower Based on Force Measurement Test in a Wind Tunnel

Television towers have a complex aerodynamic shape and low damping characteristics. As such, the wind load and the wind induction response are key factors in their design and maintenance. To study these two parameters of high-rise TV towers, a wind tunnel force test was conducted at a height of 280 m using the Foshan TV tower as a model. The TV tower model was divided into seven detachable sections. Three wind fields with different turbulence intensities were simulated in the wind tunnel, corresponding to different sections, and lateral force tests were performed on each section using a high-frequency dynamic balance. The experimental results were used to calculate the wind-induced response when considering the modal (first three-order) coupled response and were compared with the wind-induced response calculated using the complete quadratic combination (CQC) method. The results revealed that equivalent static wind loads (ESQL) and CQC calculation methods were used in this study, and a higher degree of coincidence was observed, which may be useful in engineering practice.

Seismic Response Mitigation of a Television Transmission Tower by Shape Memory Alloy Dampers.

High-rise television transmission towers are of low damping and may vibrate excessively when subjected to strong earthquakes. Various dynamic absorbers and dampers are proposed to protect television transmission towers from excessive vibrations and damages. Up to now, the seismic damage reduction in television towers, using SMA dampers under seismic excitations, has not been conducted. To this end, the response reduction in a flexible television tower, disturbed by earthquakes using SMA dampers, is conducted in this study. A two-dimensional dynamic model is developed for dynamic computation at first. The mathematical model of an SMA damper is proposed, and the equations of motion of the tower, without and with, are established, respectively. The structural dynamic responses are examined in the time and the frequency domain, respectively. The effects of damper stiffness, service temperature, hysteresis loops, and earthquake intensity on control efficacy are investigated in detail. In addition, the power spectrum density curves, of dynamic responses and the energy responses, are compared to provide deep insights into the developed control approach. The control performance of SMA dampers is compared with that of widely-used friction dampers. The analytical observations indicate that SMA dampers with optimal parameters can substantially reduce the vibrations of TV transmission towers under seismic excitations.

A combined algorithm for denoising GNSS-RTK positioning solutions with application to displacement monitoring of a super-high-rise building

Given that global navigation satellite system (GNSS)-based real-time kinematic (GNSS-RTK) monitoring accuracy is easily interfered with by residual errors, a combined algorithm is proposed for signal denoising with application to the GNSS-RTK positioning solutions of a super-high-rise building; namely, the Tianjin Radio and Television Tower in China. The proposed denoising algorithm is a combination of the Butterworth high-pass filter and complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), after which the intrinsic mode function components are selected based on the effective coefficient, the correlation coefficient and the power spectral density. After signal filtering, the structural dynamic deformation is 36.0 mm in the horizontal directions and 48.4 mm in the up-direction. Two orders of natural frequencies of the Tianjin Radio and Television Tower are successfully identified (i.e. 0.1583 Hz and 1 Hz). In addition, the relative error of the fundamental frequency is less than 0.44% compared with previous studies. The results reveal the reliability of the combined Butterworth–CEEMDAN algorithms for dealing with GNSS-RTK measurements. Moreover, the improvement in the GNSS-RTK sampling frequency is conducive to extracting more helpful monitoring information. Furthermore, the dynamic deformation data in this paper indicate that the Tianjin Radio and Television Tower is operating normally.

Подавление узкополосных стационарных помех в телеметрическом комплексе на основе автокомпенсатора с удаленными каналами.

The problem of combating stationary interference in the areas of operation of ground-based telemetry systems is considered. One of the most annoying types of interference is high-power narrowband TV interference. They are emitted from television towers and their position is known in advance. A solution to this problem is proposed by using a multichannel auto-compensator with a non-standard arrangement of compensation channels. An analytical solution is obtained for the optimal weight vector of the auto-compensator of interference, based on the method of power vectors. This method does not require direct inversion of the interference correlation matrix. The computational complexity of the proposed method is estimated and it is shown that it has a much lower computational complexity compared to the method of direct inversion of the interference correlation matrix. The results of numerical simulation of the interference suppression coefficient are presented. Its effectiveness has been shown.

3D Reconstruction of a Complex Grid Structure Combining UAS Images and Deep Learning

The latest advances in technical characteristics of unmanned aerial systems (UAS) and their onboard sensors opened the way for smart flying vehicles exploiting new application areas and allowing to perform missions seemed to be impossible before. One of these complicated tasks is the 3D reconstruction and monitoring of large-size, complex, grid-like structures as radio or television towers. Although image-based 3D survey contains a lot of visual and geometrical information useful for making preliminary conclusions on construction health, standard photogrammetric processing fails to perform dense and robust 3D reconstruction of complex large-size mesh structures. The main problem of such objects is repeated and self-occlusive similar elements resulting in false feature matching. This paper presents a method developed for an accurate Multi-View Stereo (MVS) dense 3D reconstruction of the Shukhov Radio Tower in Moscow (Russia) based on UAS photogrammetric survey. A key element for the successful image-based 3D reconstruction is the developed WireNetV2 neural network model for robust automatic semantic segmentation of wire structures. The proposed neural network provides high matching quality due to an accurate masking of the tower elements. The main contributions of the paper are: (1) a deep learning WireNetV2 convolutional neural network model that outperforms the state-of-the-art results of semantic segmentation on a dataset containing images of grid structures of complicated topology with repeated elements, holes, self-occlusions, thus providing robust grid structure masking and, as a result, accurate 3D reconstruction, (2) an advanced image-based pipeline aided by a neural network for the accurate 3D reconstruction of the large-size and complex grid structured, evaluated on UAS imagery of Shukhov radio tower in Moscow.

Dynamic response reconstruction for structural health monitoring using densely connected convolutional networks

This article proposes a novel dynamic response reconstruction approach for structural health monitoring using densely connected convolutional networks. Skip connection and dense block techniques are carefully applied in the designed network architecture, which greatly facilitates the information flow, and increases the training efficiency and accuracy of feature extraction and propagation with fewer parameters in the network. Sub-pixel shuffling and dropout techniques are used in the designed network and applied to reduce the computational demand and improve training efficiency. The network is trained in a supervised manner, where the input and output are the measurements of the available channels at response available locations and desired channels at response unavailable locations. The proposed densely connected convolutional networks automatically extract the high-level features of the input data and construct the complicated nonlinear relationship between the responses of available and desired locations. Experimental studies are conducted using the measured acceleration responses from Guangzhou New Television Tower to investigate the effects of the locations of available responses, the numbers of available and unavailable channels, and measurement noise. The results demonstrate that the proposed approach can accurately reconstruct the responses in both time and frequency domains with strong noise immunity. The reconstructed response is further used for modal identification to demonstrate the usability and accuracy of the reconstructed responses. The applicability of the proposed approach for structural health monitoring is further proved by the highly consistent modal parameters identified from the reconstructed and true responses.

Broadcasting from the “Mediated Center:” Baltimore’s Candelabra Television Tower, circa 1959

ABSTRACTThe rise of post-WWII television markets around the world required new technical solutions for broadcast media. These solutions became novel examples of urban-scale infrastructure, including the “television tower” as a unique structure. Among early American examples is Baltimore’s three-mast “candelabra” television tower, completed in 1959. Although the project’s feasibility depended upon advances in structural design, its most significant innovation was institutional. As an early example of “infrastructure sharing,” Baltimore’s candelabra tower illustrates how innovative built form can engender a new relationship among technology, urban infrastructure, and the production of cultural capital.

Расчет динамических характеристик телевизионной башни

The paper considers the calculation of dynamic characteristics of a television tower exposed to wind pulsation. During the investigation, the tower outline shape was changed, as well as the material of the structure, then it was subjected to the wind load using the SCAD ++ computer complex.

A novel experience-based learning algorithm for structural damage identification: simulation and experimental verification

ABSTRACT A simple yet powerful optimization algorithm, named the experience-based learning (EBL) algorithm, is proposed in this article for structural damage identification based on vibration data. This algorithm is free from any algorithm-specific control parameters and requires only common control parameters. The natural frequencies and/or mode shapes are utilized in establishing an objective function. The efficiency and robustness of the proposed method are demonstrated by two numerical examples, namely a television tower and a functionally graded material beam. A set of experimental work on a cantilever beam is studied for further verification. Both numerical and experimental results confirm the superiority of the proposed EBL algorithm in terms of convergence and accuracy for structural damage identification, in comparison with particle swarm optimization, the cloud model-based fruit fly optimization algorithm, squirrel search algorithm and teaching–learning-based optimization.

Predictions on the dynamic behaviour of an aeroelastic model of a television tower in the boundary layer wind tunnel

This paper presents the process of making a set of vibration measurements on a model of a television tower in the boundary layer wind tunnel. The main objective of the study is to predict the dynamic behaviour of the full-scale structure under the turbulent wind action, specific for the Bucharest site, in Romania. Wind tunnel tests were performed on a 1:500 scale aeroelastic model, existing at the Aerodynamics and Wind Engineering Laboratory “Constantin Iamandi” from the Technical University of Civil Engineering Bucharest. As a result of the vibration measurements on the tower's model, the dynamic behaviour of the structure on the real scale could be determined by using the conditions and relationships of similitude established between the two, model and prototype (full-scale structure). The experimental analysis made in this study may be very important not only in assessing the dynamic response for a building of such importance, during the preliminary stages, but also can be very helpful for the decision makers involved in the design process to choose which is the best solution for such high and slender structures under the action of turbulent wind.