Single Tower Research Articles

Study on Double-Deck and Four-Cable Stayed Bridge with Univalent Hyperboloid Column Tower

Aiming for the citywide deck cable-stayed bridge, a double separated deck and four-cable stayed bridge with univalent hyperboloid single column bridge tower was proposed. The bridge deck with double separated steel box girders replace the bridge deck wide steel box girder, the univalent hyperboloid single column bridge tower replaces the double column bridge tower, and the four-cable stayed bridge replaces the double-cable stayed bridge. The univalent hyperboloid single column tower bridge has a thick bottom, which can ensure the bearing capacity of the single column tower structure; the waist of the bridge tower is small and the driver’s vision is wide; the wider top of the bridge tower can facilitate the scattered anchoring of stay cables. Combined with the 200 m+420 m+200 m double separated deck and four-cable stayed bridge with the univalent hyperboloid single column tower, the engineering parameters are designed, the Midas finite-element analysis model is established, the static analysis and dynamic modal analysis are carried out, and the structural rationality of double separated deck and four-cable stayed bridge with the univalent hyperboloid single column tower is verified.

Characteristics of wind loads on Twin-Tower structure in comparison with single tower

To provide a general guidance for the wind-resistant design of super-tall twin towers, a study was conducted to investigate the aerodynamic and structural dynamic characteristics of twin towers in comparison with the isolated single tower. It was found that the mutual aerodynamic interference between two towers may have a beneficial effect of disrupting the regular shedding of vortices and causing the across-wind oscillation of the twin towers appreciably smaller than that of the single tower. This beneficial effect is a function of the relative spacing between two towers and the wind direction. When the twin towers are side-by-side to wind, the beneficial effect is apparent if the relative spacing is about 1.0 or less, but it becomes negligible when the relative spacing reaches 2.0. When the twin towers are in tandem configuration to wind, the beneficial effect will remain valid until the maximum tested relative spacing of 2.0. It is also found that wind forces applied to the twin towers may contain a large proportion of out-of-phase components, which act on the two towers in opposite directions, and the corresponding structural response can be well controlled by structural links between the two towers. Therefore, the role and effectiveness of structural links in controlling wind-induced structural responses can be evaluated by the percentage of the out-of-phase components over the total wind forces, which is again a function of the relative spacing, design wind speed, wind direction of concern, and reduced building frequencies. A case study of the 570 m super-tall twin towers verified the conclusions drawn from the general study, and the use of structural links was proved to be able to reduce the design wind loads and building accelerations by more than 20%.

Dynamic response analysis of cable-stayed bridge under random traffic flow and fleet

The vehicle-bridge coupling vibration (VBCV) theory is being applied in the safety evaluation of existing bridges, such as cable-stayed bridge. In order to study the dynamic performance and vibration response of urban long-span cable-stayed bridges under traffic flow, and provide reference for the design, construction and safety assessment of existing bridges, the urban cable-stayed bridge with single tower and double cable in service was taken as the research object. The dynamic response of bridges under vehicles with different number, distance, speed and weight was analyzed. And the VBCV of bridge under different vehicle density and speed was discussed. The traffic flow on the bridge was simulated by the cellular automaton (CA) model, a half car model with four degrees of freedom was established, and the bridge models were established by the ANSYS software. According to the displacement coordination and mechanical balance conditions, the two models were connected, and were solved by MATLAB software. The dynamic response of the vehicle-bridge system under the vehicle fleet and random traffic flow was investigated. The research results showed that the vertical displacement (VD) of the main span increased with the number of vehicles, conversely, the vertical vibration acceleration (VVA) decreased. As driving distance increased, the VD and VVA of main span decreased. The VD of main span was not sensitive to the vehicle speed, but the VVA increased with the vehicle speed. The VD and VVA of the main span increased with the vehicle weight, and the VD of main span was proportional to the traffic density. As the traffic density increased, the VVA increased first, then decreased.

Predicting wind-induced structural response with LSTM in transmission tower-line system

Wind-induced dynamic response of the nonlinear structure is critical for the structural safety and reliability. The traditional approaches for this response including observation or simulation focus on the structural health monitoring, the experiment, or finite element model development. However, all these approaches require high cost or computational investment. This paper proposes to predict the wind-induced dynamic response of the nonlinear structure with a novel deep learning approach, LSTM, and applies this in a structural lifeline system, the transmission tower-line system. By constructing the optimized LSTM architectures, the proposed method applies to both the linear structure, the single transmission tower and the nonlinear structure, the transmission tower-line system, with promising results for the dynamic and extreme response prediction. It can conclude that the layers and the hidden units have a strong impact on the LSTM prediction performance, and with proper training data set, the computational time can significantly decrease. A comparison surrogate model developed by CNN is also utilized to demonstrate the robustness of the LSTM-based surrogate model with limited data scale.

Modeled Surface‐Atmosphere Fluxes From Paired Sites in the Upper Great Lakes Region Using Neural Networks

AbstractThe eddy covariance (EC) method is one of the most widely used approaches to quantify surface‐atmosphere fluxes. However, scaling up from a single EC tower to the landscape remains an open challenge. To address this, we used 63 site years of data to examine simulated annual and growing season sums of carbon fluxes from three paired land‐cover type sites of corn, restored‐prairie, and switchgrass ecosystems. This was also done across the landscape by modeling fluxes using different land‐cover type input data. An artificial neural network (ANN) approach was used to model net ecosystem exchange (NEE), ecosystem respiration (Reco), and gross primary production (GPP) at one paired site using environmental observations from the second site only. With a mean spatial separation of 11 km between paired sites, we were able to model annual sums of NEE, Reco, and GPP with uncertainties of 20%, 22%, and 8%, respectively, relative to observation sums. When considering the growing season only, model uncertainties were 17%, 22%, and 9%, respectively for the three flux terms. We also show that ANN models can estimate sums of Reco and GPP fluxes without needing the constraint of similar land‐cover‐type, with annual uncertainties of 12% and 10%. These results provide new insights to scaling up observations from one EC site beyond the footprint of the EC tower to multiple land‐cover types across the landscape.

Automatic Detection of Transmission Line Dangerous Points Based on Point Cloud Tower Section Classification Mode

In the actual laser power inspection data processing process, the classification error of point cloud is inevitable. Some classification errors often need to be located with the help of dangerous points which is detected by mistake. Therefore, in the process of laser power inspection point cloud data processing, the detection of Dangerous points often needs multiple calculations. However, the dangerous point detection is often based on the whole line, and involves the data calculation of hundreds of tower section at the same time. The data magnitude is large and the calculation speed is slow, which seriously affects the efficiency of point cloud category correction. Aiming at the above problems, this paper divides the point cloud into tower segments, transforms the calculation unit of dangerous point detection from a whole line to a single tower segment, and records the modification of the point category in the tower segment. In the process of correcting the classification error and repeatedly calculating the dangerous points, only the tower segment with the modified category is recalculated. The practical application shows that this method can effectively speed up the data processing efficiency of laser power inspection.

Dual-tower CSP plants: optical assessment and optimization with a novel cone-tracing model

Solar tower systems show significant prospects based on their room for improvement in the solar thermal industry. Despite not being an entirely new concept, multi-tower systems have not been extensively studied in the literature yet. An optical optimization model is presented to evaluate the feasibility of dual-tower systems, where each heliostat can select the most convenient receiver. There is a number of optimization variables, which makes it essential to implement a fast optical algorithm capable of evaluating the field optical efficiency. Taking advantage of the tower central receiver's axial symmetry, an integration method is proposed to work out the individual spillage for each heliostat. As a result, an optimal design has been accomplished where 32 representative days (with several time-points each) have been taken into account to assess the yearly-averaged optical efficiency of the whole solar field. Thus, it can be concluded that a ∽1.5% increase in the annual optical efficiency can be achieved with respect to the analogous single tower system.

Analysis of tower foundation of long span single tower cable stayed bridge

The pylon is an important stressed structure in the single pylon cable-stayed bridge. The rationality of bearing platform and pile foundation of pylon foundation is one of the key research contents in the design of single pylon cable-stayed bridge. The main bridge of Tarim bridge in Xinjiang is a single tower double span cable-stayed bridge with span arrangement of (41 + 168 + 168 + 41) m and total height of cable tower of 125m. Arc shaped concrete tower columns are adopted. The stress of cable tower foundation is complex. The stress analysis of foundation scheme is one of the key problems of this project. In this paper, the geological conditions, structural stress, economic rationality, construction convenience and other factors are comprehensively considered, the different foundation types are compared and analyzed, the reasonable foundation type and layout type are determined, and the stress of the pile and cap structure of the main tower foundation is calculated and analyzed. Through the solid finite element model, this paper analyzes the influence of the stiffness deformation of pile cap on the stress of pile group foundation. The calculation results show that the stress of dumbbell shaped pile cap is more reasonable than that of rectangular foundation pile cap, and the number of pile foundation and the calculated pile length are reduced in varying degrees. By adjusting the pile foundation arrangement under dumbbell shaped foundation, the stress of pile foundation can be more uniform, which can be used as the foundation for similar projects. The foundation design provides reference and reference.

Influence of finite element structural modification on dynamic characteristics of transmission tower

Taking a 500kV dry type single circuit angle tower as the research object, the computational modal analysis of the established finite element calculation model is carried out. It is found that local vibration occurs at the bottom of the transmission tower. The weakness of the original structure lies in the intersection of the longest web, the deformation displacement of the joint is the largest, so the structure needs to be strengthened. There are two corresponding strengthening methods: Diamond reinforcement and positive cross reinforcement. Further analysis results show that the regular cross structure has a certain strengthening effect on the original structure.

Predicting single freestanding transmission tower time history response during complex wind input through a convolutional neural network based surrogate model

As the steel towers in the power system are vulnerable to intensive wind loads, it is essential to understand their dynamics response to estimate its potential failure. Conventional structural analysis methods like the finite element analysis or the field test are either computational heavy or cost expensive. Thus, this paper proposes a machine learning approach based on convolutional neural network (CNN) to predict the time history response of the transmission tower during the complex wind input. By preprocessing the time history of wind load and the tower’s dynamic response, a well-developed CNN can capture the time and spatial correlation of the wind load successfully and provide high accuracy results. CNN configuration, window size selection, and training data scale are carefully discussed to optimize the CNN design to maximize the prediction accuracy as well as minimize its computational time. Finally, to evaluate the performance of the surrogate model, the accuracy of the optimal CNN is tested in predicting the time history response of the transmission tower under 15 m/s to 70 m/s wind speed. The effectiveness of the CNN surrogate model is validated through a fragility model development, and its robustness is investigated using two wind inputs generated from a random wind profile and a random wind spectrum.

Structural analysis of a multi-tower building with a large chassis in a business district

A business district building consists of two tower structures with basements and common podium and is a multi-tower structure with large chassis. The structural layout of the two towers is identical, both adopt the frame-core tube structure system with a total structural height of 156.85m. The seismic response characteristics of multi-tower structure with large chassis were analyzed through comparing the calculation results of single-tower model by SATWE software and multi-tower model with large chassis by MIDAS software.The results show that the seismic shear force of the podium significantly reduces and the seismic shear force of the towers up the podium increases. The vibration mode of the two-tower structure contains the vibration of two single towers, but it is not a simple superposition of dynamic characteristics, which is more complex.

Research on Type Selection of Diving Tower in 110kV Single and Double Circuit Transmission Line

With the continuous development of EHV (UHV) transmission lines，new lines often need to drill through the built lines，so it is urgent to study the type of diving towers. Based on typical weather conditions and commonly used ground wire models, the basic type and tower type selection of 110kV single and double circuit overpass towers in high altitude areas are studied, and two single and double circuit overpass tower schemes are planned and arranged. And according to the pole tower structure design and optimization theory, the 110kV single-circuit diving tower and the 110kV dual-circuit diving tower are optimized from the structural optimization layout and the pole tower structure node optimization design. The research results show that the single-circuit diving tower adopts the wine glass tower, and the wires are arranged horizontally, and the double-circuit diving tower effectively reduces the height of the tower. The dish-shaped tower is used, and the single-circuit wires are arranged in a triangle pattern, which provides a certain practical guiding significance for the 110kV diving-across technology application.

Numerical investigation of dynamic behaviour of single and two hinged articulated towers in random sea

The present paper deals with comparative studies on hydrodynamic behaviour of Single and two hinged articulated towers in Random sea. The dynamic behaviour of towers is investigated under long crested Uni directional random sea and the wave force calculations are performed using Modified Morison equation. A visual based C + + program is developed to evaluate the response of the towers by taking into account non linearities like time variation of submergence, instantaneous tower orientation and hydrodynamic loading. Finally, the equations of dynamic motion are solved using New Mark integration scheme followed by Fast Fourier transform to obtain Power spectral densities. From results, it is observed that presence of intermediate hinges reduced the spectral energy coming on Two hinged articulated tower indicating its significance over Single hinged towers.

„Maestri muratori” și constructori transilvăneni, în cadrul programului arhitectural al „Episcopiei Greco-Catolice Gherla”, în perioada 1853-1918

"“Maestri muratori” and Transylvanian builders, within the architectural program of the “Greek Catholic Episcopate Gherla” between 1853 and 1918. In the second half of the 19th century, in Transylvania there was a demand for specialized labor, on construction sites such as the construction of railways, the construction of roads and bridges for which Italians came from areas with a recognized constructive tradition, such as those in the Trentino area, are encouraged and supported by the Austrian administration to emigrate. The Italian emigrants in Transylvania, mostly working in the field of construction, were a community poor in resources, but rich in human resources and entrepreneurship. In the alternative, these Italian builders, “master builders”, permanently established in Transylvania will contract smaller construction sites, proposals of wealthier rural parish communities, the case of former border villages able to financially support more elaborate constructions, morpho-stylistically and decoratively, regulated under the umbrella of the same imperial restrictions under which it was built in all Austrian provinces of the period. In the absence of relevant archival data on the paternity of the buildings discussed here, the priority tool of this study to identify the collaboration of Italian “master builders” is the stylistic investigation based on the certainty of their presence in the context of three church buildings related to the reference period: from Cășeiu, built by Antonio Baizero from Udine, the Roman Catholic church from Ileanda, built by Italian emigrants to serve their religious service and the church from Livada (Dengeleag), built by Lorenzo Zottich, possibly belonging to a second generation of emigrant builders Italians in Transylvania. All these constructions have common stylistic features, integrated into one of the three representative categories, identified within the “Greek Catholic Episcopate of Gherla”, namely the most elaborate architectural model agreed by the Austrian authorities: rural churches with a single tower on the facade, tower with a neoclassical baroque-inspired profiling that also involves the most complex local level of labor of the moment. In the context of the lack of relevant archival data on the constructive paternity in most of these buildings, the identification of the presence and participation of Italian builders on construction sites within the “Greek Catholic Diocese of Gherla” uses as main study tool, stylistic analysis of monuments, which results in the launch of hypotheses meant to be validated in the future through applied studies by the archive. Morpho-constructive characteristics similar to the churches in Cășeiu, Ileanda, Livada (Dengeleag) crowned by the presence of the neo-baroque tower, the corrugated cornice that integrates decorative clocks, with a high level of difficulty in terms of construction, indicate a possible presence of Italian emigrant builders: Orman, Cluj County (1865-1867), Livada - Dindeleag, Cluj County (1868), Buciumi, Sălaj County (1872), Rus, Sălaj County (1890-1894), Poieni, Cluj County (1892), Apahida (1892), Borșa (1900), Dobricul Mare, Bistrița Năsăud county (1902), Sâncraiu Almașului, Sălaj county (1902), Agrieș, Bistrița Năsăud county (1905-1906), Șieu Cristur (1906), Bistrița Năsăud county, Lunca Ilvei (1906-1910), Bistrița Năsăud county, Chizeni (1910), Bistrița Năsăud county, Urișor (inc. 1910), Cluj county, Rohia, Maramureș county (1911), Church from Sașa (1907-1911), Alba county, Diviciorii Mici, Cluj county, (1912), Surduc, Sălaj county (1913), Câțcău, Cluj county (1914). However, the final demonstration remains to be validated following documented related archival studies. Keywords: Italian emigrants, Greek catholic architecture, “Greek Catholic Episcopate Gherla”, Greek catholic church from Cășeiu, Italian Roman catholic church in Ileanda, Greek catholic church from Livada (Dengeleag), Lorenzo Zottich, Antonio Baizero da Udine "

Dynamic Response Study of a Single Tower Cable Stayed Bridge using Finite Element Method

Cable-stayed bridges are most widely used in modern bridge construction. The dynamic response of a single tower cable-stayed bridge is studied by performing nonlinear dynamic analysis using finite element method based software ANSYS. A three-dimensional bridge model was developed. Steel cables were simulated using a single element approach. Due to the coupling effects, the bridge exhibits complex modal shapes. The response of the bridge in the vertical direction is more elastic and flexible as compared to the longitudinal and transverse direction. The response of the critical sections of girder, tower, and cables was also studied by time-history analysis using the ground acceleration data of EI-Centro 1940. A 10-second ground data with 0.0001 second time step was used.

Dynamic Response Study of a Single Tower Cable Stayed Bridge using Finite Element Method

Cable stayed bridges are most widely used in the modern medium to long bridge construction due to their efficient response, economic viability, faster construction, and eye-catching aesthetics. The dynamic response of a single tower cable stayed bridge is studied by performing both nonlinear static and dynamic analyses using finite element method based software ANSYS. A three dimensional bridge model was developed using ANSYS. The steel cables were simulated using a single element approach to minimize the time and data use. Due to the complexity of cable stayed bridges, it is tried to avoid the convergence problems by adopting the displacement convergence approach. The bridge exhibits complex modal shapes due to the coupling effects for the free vibrations. The response of the bridge in vertical direction is more elastic and flexible as compared to the longitudinal and transverse direction. Response of the critical sections of girder, tower, and cables was also studied by time-history analysis using the ground acceleration data of the EI-Centro 1940 earthquake. A 10 second ground data with 0.0001 second time step was used. It was observed that stiffness in the vertical direction is a key player in the dynamic behavior of the cable stayed bridge. The response of the right and left span is similar which adds to the accuracy of the analysis. Time history analysis of the bridge shows that the largest displacements or peak responses are not related to the peak ground accelerations, rather they are dependent on many other factors like bridge stiffness, nature of the earthquake ground excitations and mass distribution. However, the results show the general trend of cable stayed bridges.

Revealing the Dynamical Transition of Anisotropy Behind the HOST by Koopman Analysis

AbstractThe hockey‐stick transition (HOST), which is depicted by the “local and global shear” assumption, about the turbulence kinetic energy with the averaged flow intensity is noticed widely. However, the intrinsic mechanism of averaged flow influences turbulence kinetic energy via shear and buoyancy is missing. In this research, we deploy the Koopman operator to expose invariant subspaces of the Ri series to identify the quasiperiodic coherent structures from the single tower observation. Analysis of turbulence fluxes and anisotropy demonstrates the mechanism, that is, horizontal kinetic energy coupled with vertical downward flux, whereby anisotropy evolution is changed. Examining the anisotropy invariants changing with kinetic energy reveals a dynamical transition that determines the threshold of HOST. Moreover, the mechanism about how the shear and vertical momentum influences the transition point of HOST is at first given by a group of a quadratic relationship when the anisotropy crossed over the transition point.

A method to obtain the wind field characteristics of super-large aperture radio telescope site based on single-point wind tower and numerical simulation

The influence of wind on the pointing accuracy of large aperture radio telescopes is becoming increasingly serious, especially at high observing frequency. Obtaining the wind field characteristics efficiently is very important to reduce the wind disturbance on antenna structure. In this paper, an error evaluation of numerical simulation method is established based on the measured data of single point wind tower, and the wind field characteristics are obtained from the evaluated numerical simulation results combined with the measured data for the 110 m aperture QiTai radio Telescope (QTT) site. According to the simulation results, compared with the measured data, the root mean square error (RMSE) of wind speed is less than 1 m s−1, and the minimum wind speed RMSE is 0.2 m s−1. An analysis of the wind field characteristics of the QTT site suggests that the active wind resistance design of the antenna periphery should focus on the SSW (south-south-west) direction.

The Single Gothic Towers of the Two Franciscan Churches of Bratislava and Sopron and Their Possible Connections to Vienna

The Single Gothic Towers of the Two Franciscan Churches of Bratislava and Sopron and Their Possible Connections to Vienna

Geospatial coherence of surface-atmosphere fluxes in the upper Great Lakes region

Surface-atmosphere fluxes are known to vary at multiple time scales, but uncertainty is high as to how fluxes change spatially within regions. With an increase in the number of eddy covariance towers, we are now able to examine the geospatial coherence of ecosystem fluxes, using time-series correlation. Eighteen sites from Michigan and Wisconsin were used in this study, ranging from 100 m to 600 km apart. Surface-atmosphere fluxes from a six-month period were used to quantify spatial coherence on a pair-wise basis. Using geospatial statistics, carbon and sensible heat (H) fluxes were found to be 95% correlated directly outside of their flux footprint and 56% correlated up to a distance of ~35 km. Latent (LE) and momentum (τ) fluxes were less correlated, 83% directly outside of their flux footprint and 40% at a distance of ~130 km albeit, at a much larger spatial distance than for the carbon and sensible heat fluxes. All fluxes showed strong spectral resonance at diel and seasonal timescales, with 1-, 2- and 3-month periods being common modes of variability among H, LE, and τ fluxes. Results based on Empirical Orthogonal Function show distinct transitions of net ecosystem exchange from fall to winter before photosynthesis or respiration while H and τ do not exhibit coherent trends. This work demonstrates the potential of quantifying geospatial coherence of surface-atmosphere fluxes in the Midwestern United States, with the ability to predict fluxes beyond the spatial limit of a single flux tower footprint. Ultimately, expanding the flux measurements to larger scales would allow better spatial scaling of terrestrial surface-atmosphere fluxes between tower footprint and modeling or remote sensing scales.