Tower Structure Research Articles

Experimental study on the joint bearing behavior of segmented tower structures subjected to normal and bending shear loads

AbstractThis article deals with the analysis and evaluation of the structural behavior of segmented tower constructions in large‐scale experimental investigations. For this purpose, a tower model with dry horizontal joints on a scale of approximately 1:10 is constructed and loaded. The objective of these large‐scale investigations is to determine the load‐bearing behavior of concrete segment towers subjected to normal force (external prestressing), bending, shear force and torsion and to derive more efficient and realistic design models. The transfer of shear stresses between individual segments is ensured by frictional resistance in the horizontal joints due to prestressing. The current design models are based on plane flange surfaces at the top and bottom of the segments as well as their ideal circular ring shape. This assumes a constant normal stress distribution for the compression connection. Within the large‐scale experimental tests, findings for uneven force distribution in the horizontal joints due to prestressing and shear bending were obtained, that have a significant impact on the design models. However, for the evaluation of the results and the projection onto the real construction components, the scale effects must be urgently taken into account.

Design of an Origami Crawling Robot with Reconfigurable Sliding Feet

This paper presents a novel reconfigurable crawling robot based on an origami twisted tower structure. Compared with other origami structures, the twisted tower can achieve extension, contraction, and bending motions as the flexible body parts in robotic designs. The kinematics of a one-layer twisted tower were analyzed with rotation and bending angles. The mechanical properties of the one-layer, two-layer, and four-layer twisted towers were compared with compression experiments. A rope-motor-driven crawling robot was designed to realize forward, backward, left-turning, and right-turning motions. Two types of crawling robot with specific sliding feet were developed to adapt to different ground conditions: one made of rubber, and the other embedded with an electromagnet. The experimental results show that the proposed robots can move at an average forward speed of 0.48 cm/s on a wooden desk, and at 0.52 cm/s forward speed or 0.65 cm/s backward speed on an iron platform.

Vibration Control of a Wind-Excited Transmission Tower-Line System by Shape Memory Alloy Dampers.

To be typical electrical power infrastructures, high-rise tower-line systems are widely constructed for power transmission. These flexible tower structures commonly possess small damping and may suffer strong vibrations during external excitations. The control approaches based on various devices have been developed to protect transmission towers against strong vibrations, damages, and even failure. However, studies on the vibrant control of wind-excited tower-line systems equipped with SMA dampers have not yet been reported. To this end, the control approach for wind-excited tower-line systems using SMA dampers is conducted. The mechanical model of the tower-line system is established using Lagrange’s equations by considering the dynamic interaction between transmission lines and towers. The vibration control method using SMA dampers for the tower-line coupled system is proposed. The control efficacy is verified in both the time domain and the frequency domain. Detailed parametric studies are conducted to examine the effects of physical parameters of SMA dampers on structural responses and hysteresis loops. In addition, the structural energy responses are computed to examine the control performance.

Determining the Optimal Scalar Intensity Measure of Floor Communication Towers

Various structural types and ground motion characteristics lead to distinct intensity measures of structural seismic performance. For the lattice high-rise steel structure of communication towers, determining the intensity measures to adjust ground motion is critical. Additionally, a crucial problem is whether the ground motion intensity parameters of pulse-like ground motion and ordinary ground motion are consistent. In this study, a standard floor four-leg angle steeled communication tower was considered the study object, and 50 pulse-like ground motions and 50 ordinary ground motions were identified to form a pulse-like ground motion set and ordinary ground motion set, respectively. For comparative analyses, 15 ground motion parameters, including amplitude, spectrum, duration, and energy parameters, were selected. The results revealed that for the lattice towers, such as communication tower, under the action of pulse-like ground motion or ordinary ground motion, efficiency, practicability, and sufficiency should be considered. Furthermore, the most suitable intensity measure was the spectral acceleration corresponding to the natural period of the tower. This study provides a basis for selecting the ground motion for dynamic time history analysis of the lattice steel tower.

Structural Vibration Analysis of Historical Drum Tower Structure Caused by Underground Train Running

The vibration induced by underground metro operation could have significant impacts on the safety of building structures. In this study, the dynamic response of the Nanjing Drum Tower affected by the metro line four operation was investigated by a three-dimensional FEM coupling train-track-tunnel-foundation-soil-basement–Drum Tower model performed on a 64 CPU parallel computing cluster platform. The results show that the vertical vibration caused by the subway operation has a more serious impact on the historical structure of the Drum Tower than the horizontal vibration. The vertical vibration attenuates rapidly from the basement bottom to the top of the tower. The horizontal vibration amplifies along the height of the historical building. The truss roof significantly weakens the vibration. As the speed of the train increases, the amplitude of horizontal and vertical vibration increases gradually from the bottom to the roof of the Drum Tower despite a relatively smaller increase for the horizontal vibration. As for the double-track operation case, the vertical vibration amplitude is much greater than that for the single-track operation, and no significant difference is observed in the horizontal direction. The amplitudes of horizontal vibration velocity for the basement and Drum Tower are 0.131 and 0.060 mm/s, respectively.

Failure mechanism and vibration control for tower tube of wind generator under extreme climate

The wind power tower is sensitive to wind loads with high aspect ratio. The failure characteristics and failure mechanism of the wind turbine tower structure are analyzed under the extreme climate conditions. Based on the principle of tuned mass damper theory, the suspension damper application in wind turbine tower structure is designed. The appropriate typhoon wind speed spectrum is selected. With the finite element software, the 3D model for tower structure is established and the control effect of the damper structure is analyzed. The maximum displacement and acceleration of the structure under extreme climatic conditions are greatly reduced after the suspension tuned mass damper being given. The efficiency of vibration reduction is 80.26% and 54% respectively. The results show that the response of displacement and acceleration for the damper are obviously decreased, which is beneficial to the safety of the tower structure under the extreme climate condition.

Wind-induced collapse mechanism and failure criteria of super-large cooling tower based on layered shell element model

Many wind-induced collapse events of super-large cooling tower have been taken place in history. Existing norms are limited within local excessive strength or buckling failure of the tower body, but ignore the follow-up phenomena after the general continuous collapse caused by local damages. Hence, they are difficult to disclose the wind-induced collapse mechanism and failure mechanism of super-large cooling tower. A case study on the world highest (228 m) cooling tower under construction in Northwest China was carried out. Variations of multi-scale wall thickness and reinforcement ratio at different positions of the tower body were considered by the layered shell element modeling method. The wind loads on the cooling tower surface were acquired through a wind tunnel test of pressure measurement on the rigid body. Displacement and internal force responses of the tower body under typical wind speeds were analyzed by combining the incremental dynamic analysis (IDA), thus determining the critical wind speed. Three redistribution of internal forces mechanisms during collapse of tower body were extracted based on the stress variation indexes before and after the node failure. Moreover, the development paths of three collapse mechanisms among units with different thicknesses of the tower body were discussed. Finally, the wind-induced failure criteria of super-large cooling tower structure were proposed based on throat deformation of the tower body. Research results demonstrated that the layered shell element model could simulate the full process of collapse of super-large cooling tower effectively and a central damage area from the throat of windward side to the center of tower body was formed. Subsequently, a crack network was formed after diffusion of the damage area along the circumferential and meridian until the complete collapse. Three redistribution mechanisms of internal forces during the collapse of the super-large cooling tower were proposed, including the sliding surface mechanism, rotating hinge mechanism and slipping surface mechanism. The super-large cooling tower structure developed wind-induced failure and collapse when the deformation failure index is δ ≥ 1.5%. It is of great significance to the design and construction of super-large cooling towers.

A data-based model for condition monitoring and maintenance planning for protective coating systems for wind tower structures

The application of protective coating systems is the major measure against the corrosion of steel structures for onshore wind turbines. The organic coatings are, however, susceptible to atmospheric exposure and tend to deteriorate during the operation. At the same time, onshore turbines become more powerful and require taller and more resistant tower structures. The inspection and condition monitoring of protective coating systems on large onshore turbines (in excess of 120 m height) is a demanding and time-consuming procedure and requires high human effort. The rapid developments in digitization and data analysis offer opportunities to notably increase the efficiency of monitoring processes and to develop (semi-)automated standardized procedures. The paper describes a data-oriented approach to utilize digital data for the monitoring and maintenance planning of surface protection systems of large onshore wind turbines. The proposed approach includes the following steps: the segmentation of an existing wind power structure into a number of reference areas based on an In-situ Virtual Twin; the definition of a local deterioration degree for each individual reference area; the annotation of image data; the use of heterogenous multi-modal data (image data, geodetical data, meteorological data, profile scanning data) as the sources for condition assessment and monitoring. An example procedure is exercised for a tower structure of an onshore wind power turbine in order to illustrate the practical relevance of the approach.

Analysis of Wind-Induced Vibration Response of High-Rise Structure of Heat Sink Tower Based on Large Eddy Simulation

Analysis of Wind-Induced Vibration Response of High-Rise Structure of Heat Sink Tower Based on Large Eddy Simulation

Bearing Capacity Analysis of Transmission Tower Structure Considering Corrosion Damage

As an important part of power grid equipment, transmission towers are in direct contact with the external environment for a long time. As a coastal city in China, Fujian has been affected by marine environment and industrial pollution for a long time, which directly affects the safety of transmission towers in long-term service. In order to explore the changes of the ultimate bearing capacity of the tower structure after corrosion, this paper uses finite element software to analyse the mechanical properties of the tower structure during long-term service, and finds that the 45° wind direction is the control condition, and the overall stiffness of the tower decreases with the growth of corrosion time, and the increment of tower top displacement reaches 7% at 12 years of corrosion. The corrosion-sensitive members of the tower were clearly identified, and their stress ratios increased from 0.78, 0.79, and 0.83 to 0.97, 0.98, and 0.99, respectively, at 12 years of corrosion.

A STUDY OF BUILDING PERFORMANCE INSPECTION BASED ON A COMBINATION OF SITE-SPECIFIC RESPONSE ANALYSIS AND STRUCTURAL ANALYSIS (A CASE STUDY OF THE LIGHTHOUSE VIEW TOWER IN BENGKULU CITY, INDONESIA)

This paper presents the implementation of site-specific analysis in observing the performance of a monumental building in Bengkulu City, Indonesia that is called the Lighthouse View Tower. This building was inaugurated in 2012. So far, it is still necessary to present the issue related to the performance of the building after 10 years. The objective of this study is to observe the performance of the building after the strong earthquake occurred. This study is first conducted by performing a site investigation. The information related to the soil profile; ground motion of the strong earthquake that occurred in Bengkulu City is collected. Furthermore, the site-specific response analysis is conducted on the site where the building stands. The results from site-specific response analysis, i.e. the actual spectral acceleration is obtained. The spectral acceleration is then used as the input parameter for finite element analysis to observe the performance of the building. The main goal of this study is to observe the structure health condition. The results show that during the strong earthquake, the structure of the view tower is still reliable and in good condition. Concern regarding the building maintenance should be emphasized. In general, the method implemented in this study could be used as the method to assess the performance of structures in other areas.

Design and analysis of building in different seismic zone & wind

It is uneconomical to design and build a structure in such a manner that it minimizes damage during an earthquake. This is because an earthquake may or may not occur during the structure's life time and is a rare phenomenon, making the construction of the structure uneconomical. The current investigation looks at a variety of existing RCC - framed structures. Because of the wind's dynamic character, it is also important in the building of towering structures, such as skyscrapers. Tall buildings and other large structures are susceptible to significant wind forces, which vary based on their location with respect to one another and their height. Using the equivalent static approach, the researchers were able to estimate wind loads on structures with a range of ratios, and the findings are shown in the following tables. When it comes to wind loads on buildings, STAAD. Pro V8i was used to calculate them and design them. It has been built to resist earthquake forces in diverse seismic zones across the world in accordance with the International Standard IS 1893 (Part 1):2002. Numerous major objectives of the research include comparing the variation in steel percent, the maximum shear force, the maximum bending moment, and the maximum deflection in different earthquake zones. The amount of uncertainty increases significantly when one moves from zone II to zone V. Increasing the percentage of steel in each zone up to zone V results in increases in the maximum shear force, the maximum bending moment, and the maximum deflection, all of which are proportional to the increase in zone V.

A 4 kV/120 A SiC Solid-State DC Circuit Breaker Powered By a Load-Independent IPT System

This article introduces a 4 kV&#x002F;120 A solid-state dc circuit breaker (DCCB) based on discrete SiC <small>mosfet</small>s. The DCCB is designed in a five-layer tower structure. Each layer consists of a circular main conduction branch and an attached gate driver. There are two primary benefits of the proposed DCCB. First, it reduces conduction loss with multiple devices in parallel. Second, it achieves an ultrafast response speed with SiC <small>mosfet</small>s. Moreover, the gate drivers of the DCCB are powered by a domino inductive power transfer (IPT) system. It achieves the load-independent constant-voltage output characteristics, which means the outputs are immune to load variations. An IPT system prototype is implemented to test the power transfer performance. At 500-kHz frequency, the total output power reaches 15.73 W, which is sufficient to power on five gate drivers, with a peak transfer efficiency of 75.4&#x0025;. The IPT system is tested to power a 4 kV&#x002F;120 A DCCB prototype. It validates that the DCCB is effective to turn off 120 A current within 3.5 <i>&#x03BC;</i>s.

Calculation method of stability bearing capacity of transmission tower angle steel considering semi-rigid constraint

Abstract The angle steel member is the most commonly used component form of the transmission tower structure. Considering its connection characteristics, we must deal with its stability analysis under semi-rigid constraint conditions for the proper study of the overall structure’s mechanical performance. Therefore, in order to establish a simple and high-precision method suitable for the ultimate bearing capacity analysis of the transmission tower, we build the refined finite element models of typical steel tower joints, analyze its moment-rotation curve and utilize simulation technique of spring elements to acquire the calculation method of its single angle stability bearing capacity, which is considering initial imperfection and residual stress. Furthermore, we analyze its bearing capacity under different constraint conditions such as rigid, semi-rigid and articulated connection. The results show that it is necessary to consider joint stiffness in the bearing capacity analyses. Finally, it’s confirmed that the calculation results of this method agree well with the experimental data, which validates its high accuracy. Therefore, the method provides technical support for high efficient component stability simulation in overall stability analyses of the transmission steel tower.

Analisis Pengaruh Faktor Dominan Terhadap Kinerja Kontrak Pelaksanaan Konstruksi Jaringan Transmisi dari Aspek Biaya, Waktu dan Mutu

The construction of 150 SUTT Transmission Line Jatigede Incomer is located in Sumedang Regency, West Java. The problems that exist in this project are: (1.) Procurement of Materials, (2.) Land acquisition, (3.) Design Changes, and (4.) The Covid-19 pandemic. As a result of these problems, the project was delayed and required an extension of 442 days (245% of the initial contract which was only 180 days) and 4.89% additional cost of the initial contract. This research aims to study the efforts in order to improve contract performance from cost, time and quality aspects. The analysis was carried out using the method of fishbone diagram analysis for two conditions, which were the initial conditions and its improvement efforts in terms of cost, time and quality, while the concept of earned value was to determine the dominant factor that caused the increase in costs and time. From the results of the analysis, it can be said that the dominant factor that affects the increase in costs is design changes which is 95% of the total amendment cost and causes an extension time of 73% of the total additional time for contract amendments. The impact of the covid-19 pandemic which resulted in the termination of the project for approximately 120 days was the dominant factor in the contract amendment (approximately 27% of 442 days). Regarding problems related to material procurement, it only causes 1.36% additional cost of the total cost amendment, which caused by transportation costs. Land acquisition carried out in stages does not result in additional time or additional contract costs. The quality of the foundation and tower structure work can be maintained in accordance with the requirements in the contract.

The role of learning style in engineering design thinking via project-based STEM course

ABSTRACT Engineering design thinking is at the core of engineering competence. Project-Based learning (PjBL) about Science, Technology, Engineering, and Mathematics (STEM), which is based on engineering design, has brought enormous success in students’ gaining and applying knowledge about STEM subjects. However, there are few studies on the perceived improvement in engineering design thinking and the possible role that learning style (LS) plays. We implemented PjBL-STEM classes to enable students to design and build a water tower using a truss tower structure that can withstand earthquakes. Constraints such as height, load weight, tower weight, and degree of earthquake withstanding were included. A total of 137 Taiwanese students participated in this course and employed a Gregorc learning style delineator to determine their learning preferences. A pre-test and post-test on perceived engineering design thinking performance was also undertaken. Students demonstrated significant improvements in their perceived engineering design thinking. Additionally, abstract-type learners had greater perceived improvement than concrete-type learners from the PjBL-STEM course. We suggest that different pedagogical methods should be utilized to provide equal opportunities for each student.

Lightning trip-out risk assessment and differential lightning protection of 35 kV transmission lines in mountain wind farm

Lightning trip out of collecting line has become a serious threat to the safe and reliable operation of mountain wind farm. It is urgent to carry out lightning trip out risk assessment and differential protection of 35kV collecting line of mountain wind farm. In this paper, considering the mountain terrain, tower structure, insulation configuration, grounding resistance and other factors, an accurate calculation model of lightning trip out rate is established, and the lightning trip out distribution law of each tower in wind farm is obtained. In this paper, the lightning trip risk of collector lines is classified according to the improved analytic hierarchy process of ”base-by-base tower – tower section – whole line”. Finally, considering the economy of wind farm lightning protection, three kinds of wind farm collector line differential protection schemes are proposed. The results show that the lightning trip-out risk assessment of the line I and line II of a wind farm is carried out by using the improved chromatography analysis method. The lightning trip rates of the line I and line II are 2.299 times/100 km⋅a and 1.740 times/100 km⋅a, respectively. This shows that the wind farm’s circuit is faced with serious lightning trip risk. Considering the effect of lightning protection and economy of lightning protection, scheme 2 is adopted to carry out the lightning protection transformation of line I and line II. The risk of lightning trip out of line I and line II is reduced by 55% and 62.7% respectively, and the technical economy of lightning protection of scheme 2 is the best. Therefore, it is suggested to adopt scheme 2 as the lightning protection transformation measure of the collection line of the wind farm. The above research can provide technical reference for lightning protection of wind farm collector lines in the future.

Aerodynamic Behavior and Stability of the Tall and Slender Brasilia Telecom Tower

The 192 m tall Brasilia Telecom Tower was designed in 1958 as part of the infrastructure of the new capital of Brazil. During its more than 55 years in service, a great number of accessories and antennas have been attached to the upper third of its height altering the lumped mass distribution and the wind loading on the tower structure. To evaluate the effect of such alterations, a comprehensive study of the aerodynamic behavior and structural stability was performed with the aid of a 3D computational model of the complete tower structure and short-term dynamic monitoring. This procedure allowed the structural model to be validated through the correlation between theoretical and experimental vibration frequencies and aerodynamic displacement amplitudes. The computational model was then used to obtain time-domain responses of the tower structure under the action of turbulent wind loading for various wind directions. It was found that the existing antennas and their supports caused a considerable increase in the aerodynamic forces and consequent response amplitudes. Two alternative solutions were then considered: structural reinforcement of elements and the installation of dynamic control devices. Both alternatives are described briefly, and their efficiency is discussed in light of the numerical results obtained.

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.

A Digital Twin concept for the prescriptive maintenance of protective coating systems on wind turbine structures

The application of protective coating systems is the major measure against the corrosion of steel for tower sections of wind turbines. The inspection, condition monitoring and maintenance of protective coating system is a demanding and time-consuming procedure and requires high human effort. The paper introduces for the first time a Digital Twin concept for the condition monitoring and prescriptive maintenance planning for surface protection systems on wind turbine towers. The initial point of the concept is an in-situ Virtual Twin for the generation of reference areas for condition monitoring. The paper describes the integration of an online image annotation and processing tool, a maintenance model, corrosive resistance parameters, structural load parameters, and sensor data into the Digital Twin concept. The prospects of the concept and its practical relevance are shown for tower structures of large onshore wind turbines.