Fragility analysis of a long-span transmission tower–line system under wind loads

2020 ◽  
Vol 23 (10) ◽  
pp. 2110-2120
Author(s):  
Li Tian ◽  
Xin Zhang ◽  
Xing Fu
Keyword(s):  
Damage Index ◽  
Element Model ◽  
Attack Angle ◽  
Fragility Analysis ◽  
Wind Loads ◽  
Collapse Mechanism ◽  
Ultimate Capacity ◽  
Transmission Tower ◽  
Line System ◽  
Long Span

Numerous transmission towers have collapsed due to experiencing strong winds; therefore, the purpose of this article is to investigate the collapse mechanism and the anti-collapse performance of a long-span transmission tower–line system. The detailed finite element model of a typical tower–line system is established in ABAQUS. A global damage index is proposed to quantitatively estimate the overall damage of the structure and define the collapse criteria. An incremental dynamic analysis is performed to obtain the collapse mechanism and the ultimate capacity of the structure. Subsequently, a fragility analysis for evaluating the anti-collapse performance is conducted due to the uncertainty of wind loads. Eventually, the influence of the wind attack angle and the length of the side spans on the fragility is discussed. The results demonstrate that the proposed global damage index is capable of quantitatively reflecting the overall damage and assessing the ultimate capacity of the structure. In addition, the uncertainty of the wind load has a significant influence on the ultimate capacity and the failure position. Furthermore, the results reveal that the wind attack angle and the length of the side spans have an apparent effect on the fragility of the structure.

scholarly journals Wind-induced collapse analysis of long-span transmission tower–line system considering the member buckling effect

2018 ◽  
Vol 22 (1) ◽  
pp. 30-41 ◽  
Author(s):  
Li Tian ◽  
Haiyang Pan ◽  
Canxing Qiu ◽  
Ruisheng Ma ◽  
Qiqi Yu
Keyword(s):  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Bending Moment ◽  
Element Model ◽  
Collapse Mechanism ◽  
Transmission Tower ◽  
Line System ◽  
Long Span ◽  
Collapse Analysis ◽  
Three Dimensional Finite Element

The collapse problem of transmission tower upon strong winds was well noted in past few years. This article analyses the wind-induced collapse problem of a long-span transmission tower–line system. The member buckling effect was particularly considered. In doing so, a three-dimensional finite element model of the long-span transmission tower–line system was established in ABAQUS based on a practical project. The transmission tower and line were simulated by the frame and truss elements, respectively. The nonlinear behavior of a compressive member was simulated using the Marshall model, and the nonconvergence of numerical calculation was set to be the collapse criterion. The critical wind speed, damage position, and collapse probability were obtained from a collapse analysis of the long-span transmission tower–line system under different wind attack angles. The collapse mechanism of the long-span transmission tower–line system under a wind attack angle of 45° was investigated, and an incremental dynamic analysis was performed to evaluate the collapse-resistant capacity of the transmission tower. The study reveals that the interaction between bending moment and shear deformation is critical to the collapse of transmission tower.

Wind-Induced Response of UHV Guyed Single-Mast Transmission Tower-Line System

2014 ◽  
Vol 501-504 ◽  
pp. 533-537 ◽  
Author(s):  
Wen Gang Yang ◽  
Bo Wen Zhu ◽  
Zhang Qi Wang
Keyword(s):  
Time History ◽  
Element Model ◽  
Wind Loads ◽  
Induced Response ◽  
Transmission Tower ◽  
Typical Structure ◽  
Line System ◽  
Mean Values ◽  
Axial Forces ◽  
Fluctuating Wind

Ultra-high voltage guyed tower is typical structure of tall and slender, with the character of nonlinear and more sensitive to wind loads. Wind load is one of the most important control loads during design phase. A single-mast guyed tower recommended by a UHV DC transmission line was set as an example in this paper. The finite-element model of transmission tower-line system was built, based on Davenport, fluctuating wind velocity time-history was simulated, the result of wind-induced response was analyzed. The result indicates that, as for displacements of the nodes on guyed tower, the mean values of wind-induced response are greater than the displacements under the static equivalent wind loads. As for axial forces of the leg members on guyed tower, the axial forces under the static equivalent wind loads are less than the max values of wind-induced response.

scholarly journals Collapse Analysis of a Transmission Tower-Line System Induced by Ice Shedding

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaxiang Li ◽  
Biao Wang ◽  
Jian Sun ◽  
Shuhong Wang ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Transmission Lines ◽  
Progressive Collapse ◽  
Element Model ◽  
Transmission Tower ◽  
Line System ◽  
Finite Element Software ◽  
Transmission Towers ◽  
Ice Shedding ◽  
The Impact

Ice shedding causes transmission lines to vibrate violently, which induces a sharp increase in the longitudinal unbalanced tension of the lines, even resulting in the progressive collapse of transmission towers in serious cases, which is a common ice-based disaster for transmission tower-line systems. Based on the actual engineering characteristics of a 500 kV transmission line taken as the research object, a finite element model of a two-tower, three-line system is established by commercial ANSYS finite element software. In the modeling process, the uniform mode method is used to introduce the initial defects, and the collapse caused by ice shedding and its influencing parameters are systematically studied. The results show that the higher the ice-shedding height is, the greater the threat of ice shedding to the system; furthermore, the greater the span is, the shorter the insulator length and the greater the dynamic response of the line; the impact of ice shedding should be considered in the design of transmission towers.

scholarly journals The Effect Analysis of Strain Rate on Power Transmission Tower-Line System under Seismic Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Li Tian ◽  
Wenming Wang ◽  
Hui Qian
Keyword(s):  
Strain Rate ◽  
Power Transmission ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Seismic Excitation ◽  
Transmission Tower ◽  
Base Shear ◽  
Effect Analysis ◽  
Line System

The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A three-dimensional finite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis and numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate the effect of strain rate on the nonlinear responses of the transmission tower and line. The results show that the effect of strain rate on the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear forces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect of strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines considering strain rate effect are larger than those of the conductors. The results could provide a reference for the seismic design of the transmission tower-line system.

Gust Response Factor of a Transmission Tower Under Typhoon

2020 ◽  
pp. 2150001
Author(s):  
Xing Fu ◽  
Wen-Long Du ◽  
Hong-Nan Li ◽  
Wen-Ping Xie ◽  
Kai Xiao ◽  
...  
Keyword(s):  
Wind Speed ◽  
Field Measurements ◽  
Element Model ◽  
Structural Safety ◽  
Transmission Tower ◽  
Response Factors ◽  
Line System ◽  
Transmission Towers ◽  
Synoptic Wind ◽  
Gust Response

The gust response factors (GRFs) of transmission towers in current standards are reviewed for synoptic winds. The collapse of most transmission towers has occurred under the high-intensity wind (HIW) caused by events such as typhoons, hurricanes, and downbursts. Thus, this paper studies the GRF of a transmission tower under the typhoon. First, the definition of GRF and its extended form for the transmission towers are developed. Then the wind speed simulation of a typhoon event is introduced. Based on the structural health monitoring (SHM) system installed on tower #32, the measured GRFs under the super typhoon Mangkhut are calculated. Then the finite element model (FEM) of the transmission tower-line system is established to simulate the dynamic response to further calculate the GRFs, which agrees well with the field measurements. Both the field measurement and simulation results show that the GRFs under the typhoon are larger than those under the synoptic wind and that the recommended GRFs in the Chinese standard underestimate the peak responses. Finally, a parametric analysis is performed, which demonstrates that the turbulence intensity, wind speed, and power-law exponent all have great effects on the GRFs of transmission towers. In the HIW-prone areas, it is recommended that the characteristics of the HIW can be considered in improving the GRF values to guarantee the structural safety of transmission towers.

A Bidirectional Pounding Tuned Mass Damper and Its Application to Transmission Tower-Line Systems under Seismic Excitations

2019 ◽  
Vol 19 (06) ◽  
pp. 1950056 ◽  
Author(s):  
Li Tian ◽  
Kunjie Rong ◽  
Kaiming Bi ◽  
Peng Zhang
Keyword(s):  
Element Model ◽  
Tuned Mass Damper ◽  
Seismic Intensity ◽  
Design Parameters ◽  
Seismic Responses ◽  
Transmission Tower ◽  
Control Effect ◽  
Seismic Excitations ◽  
Line System ◽  
Mass Damper

Failures of transmission tower-line systems have frequently occurred during large earthquakes. It is essential to control the excessive vibrations of transmission tower-line systems to ensure their safe operation in such events. This paper numerically investigates the effectiveness of using a novel bidirectional pounding tuned mass damper (BPTMD) to control the seismic responses of transmission tower-line system when subjected to earthquake ground motions. A finite element model of a typical transmission tower-line system with BPTMD is developed using the commercial software ABAQUS, with the accuracy of the results verified against a previous study. The seismic responses of the system with and without BPTMD are calculated. For comparison, the control effect of using the conventional bidirectional tuned mass damper is also calculated and discussed. Finally, a parametric study is performed to investigate the effects of the mass ratio, seismic intensity, gap size and frequency ratio on the seismic response of the system, while optimal design parameters are obtained.

Dynamic Stability and Ultimate Capacity of Suspended Dome under Earthquakes

2013 ◽  
Vol 639-640 ◽  
pp. 875-881
Author(s):  
Yong Mei Li ◽  
Kun Hu ◽  
Wei Jing Zhang
Keyword(s):  
Dynamic Stability ◽  
Structural Parameters ◽  
Single Layer ◽  
Element Model ◽  
Ultimate Capacity ◽  
Maximum Displacement ◽  
Structural Dynamic ◽  
Long Span ◽  
Small Ratio ◽  
Lattice Shell

Suspended dome is a reasonable and novel type of long-span hybrid spatial structures based upon single-layer spherical lattice shell and tensegrity system. Based upon the structural force-bearing characteristics, the combined finite element model of beam elements, truss elements and cable elements is set up. A method taking the maximum displacement on nodes under earthquake acceleration of each level as dynamic response representative parameter is proposed to study the dynamic stable ultimate capacity of suspended dome by application of the incremental dynamic analysis in combination with B-R kinetic criterion. Furthermore, considering suspended dome has the clear advantage over Single-Layer Spherical Lattice Shell for a structure with a long span and a small ratio of rise to span, the influences of factors such as structural parameters, geometric parameters, and different earthquake input are investigated on dynamic stability for a kiewitt-type suspended dome with a long span and a small ratio of rise to span. Finally of suspended dome some conclusions are obtained such as the initial defects can clearly reduce dynamic stable ultimate capacity, and since the rise-span ratio, pre-stressing level and cross section area are not monotonous as variety to the structural dynamic stability, they should be optimized to enhance or improve the structural dynamic stability, which can be rules for engineering design.

Wind-Induced Vibration Control for Transmission System Using Steel-Lead Viscoelastic Damper

2014 ◽  
Vol 597 ◽  
pp. 376-379 ◽  
Author(s):  
Feng Lin Gan ◽  
Hai Long Jiang
Keyword(s):  
Time History ◽  
Element Model ◽  
Transmission Tower ◽  
Viscoelastic Damper ◽  
Line System ◽  
Type Steel ◽  
New Type ◽  
Auto Regressive ◽  
Working Principle ◽  
Wind Induced Vibration

For wind-induced vibration of transmission tower-line system, the vibration reduction effects are studied based on a new type steel-lead viscoelastic damper. Firstly, Calculate damped coefficient basing on the test of the new type steel-lead viscoelastic damper under slow reversed cyclic horizontal loads. Then, a finite element model of transmission tower was built by using ANSYS. And the time history samples of random fluctuating wind load is obtained with the linear auto-regressive filter law principle. Next, three installation plans of dampers on tower were proposed based on analyzing the working principle damper and the structure of tower. Finally, a wind-induced vibration transient response simulation was performed respectively for the different plans. The influences of SLVD dampers on the displacement and on the acceleration of the controlled nodes were compared. SLVD damper can reduce the top node displacement by about 37.89%. The results indicated that the SLVD damper can suppress the wind-induced vibration. And through comparison, the optimal installation scheme of SLVD dampers is obtained.

Fracture and Damage Mechanism of RC Pile Group Foundation under Low Reversed Cyclic Loading

2010 ◽  
Vol 452-453 ◽  
pp. 665-668
Author(s):  
Mi Zhou ◽  
Yue Zhang ◽  
Wan Cheng Yuan
Keyword(s):  
Damping Ratio ◽  
Damage Model ◽  
Damage Index ◽  
Pile Group ◽  
Element Model ◽  
Damage Mechanism ◽  
Loading Path ◽  
Bond Slip ◽  
Long Span ◽  
Pile Cap

This document explains and demonstrates experimental activity on 4 scale-models of elevated pile cap foundation belonging to a long span continuous bridge. The foundation was composed of 9 piles, pile cap and pier and the special soil box was built to consider soil-pile-superstructure interaction. According to the test result, the development rule of the failure mode, the failure form, the load-displacement hysteretic loops and the plastic hinges mechanism etc. for specimens were summarized. Moreover, the energy dissipation capacity and the viscous damping ratio were gained. The test also provided the data to quantitatively assessment the positive effect of steel protective pipe for RC pile. Fiber beam-column finite element model considering the modified Park-Ang damage index was built in OpenSees. This damage model was proposed to consider the loading path, the pronounced pinching effect of concrete and bond-slip of the reinforcing bars in the paper. In calculation strength degradation and stiffness degradation effects were both embodied. The skeleton curves of test and numerical analysis are both consistent by comparing.

scholarly journals Parametric Study of Tuned Mass Dampers for Long Span Transmission Tower-Line System under Wind Loads

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Li Tian ◽  
Yujie Zeng
Keyword(s):  
Frequency Ratio ◽  
Damping Ratio ◽  
Vibration Reduction ◽  
Tuned Mass Damper ◽  
Reduction Ratio ◽  
Transmission Tower ◽  
Tuned Mass Dampers ◽  
Line System ◽  
Long Span ◽  
Mass Damper

A parametric study of tuned mass dampers for a long span transmission tower-line system under wind loads is done in this paper. A three-dimensional finite element model of transmission tower-line system is established by SAP2000 software to numerically verify the effectiveness of the tuned mass damper device. The wind load time history is simulated based on Kaimal spectrum by the harmony superposition method. The equations of motion of a system with tuned mass damper under wind load excitation are proposed, and the schematic of tuned mass damper is introduced. The effects of mass ratio, frequency ratio, damping ratio, the change of the sag of transmission line, and the robustness of TMD are investigated, respectively. Results show that(1)the change of mass ratio has a greater effect on the vibration reduction ratio than those of frequency ratio and damping ratio, and the best vibration reduction ratio of TMD is not the frequency ratio of 1;(2)the sag-span ratio has an insignificant effect on the vibration reduction ratio of transmission tower when the change of sag-span ratio is not large; and(3)the effect of ice should be considered when the robustness study of TMD is carried out.

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