Span Transmission Tower Research Articles

Design and characteristics analysis of a new vibration reduction system for in service long span transmission tower

The wind-induced fatigue is the main factor leading to reduction of the bearing capacity of long-span transmission towers. In order to reduce the harm of wind vibration, this paper takes the 500 kV Jiamusi region ISLSTT (in service long span transmission tower) as the research object, and a new kind of vibration reduction system is proposed based on a steel wire rope damping structure, with which the vibration characteristics of ISLSTT is analyzed. Firstly, the layout and components of the new vibration reduction system are described, and the damping performance of which is verified and analyzed by finite element method. Secondly, the nonlinear finite element dynamic simulation model of ISLSTT with the new vibration reduction system is established, and the multi-dimensional fluctuating wind speed time history satisfying Davenport wind speed spectrum is given by harmonic superposition method in the time domain. Based on the Bernoulli theorem, the corresponding time history of wind pressure is obtained, and the random wind load is applied to the finite element model to verify the feasibility and efficient of the new vibration reduction system. Finally, the aero-elastic wind tunnel test model of ISLSTT with the new vibration reduction system is built, and the time history curves of stress and acceleration at key points under different wind directions are obtained. By comparing with the un-damped system, it is demonstrated that the average damping efficiency of this method in the scale of stress and acceleration is 72.88% and 77.17%, respectively. The simulation and wind tunnel test results also demonstrate that the vibration reduction system based on wire rope damping structure can effectively reduce the vibration of ISLSTT caused by the non-uniformity of wind speed. The research results lay a solid foundation for the vibration reduction design of in service long span tower-line system in future.

Experimental and numerical analysis on the slope change joint of a quartet-steel-tube-column transmission tower

In this paper, a new type of multi-planar slope change joint (abbreviation SCJ) in a new type of long span transmission tower is presented. Difference between the new tower and regular ones lies in the tower leg. In the new tower, each leg is a built-up column constituted with four steel tubes. The SCJ is a complicated multi-planar connection in the tower. Three-dimensional loading of the joint was achieved in the experiment. Detailed configuration of the SCJ and the experimental system were introduced. Finite element models of the SCJ were established and validated against experimental results. Experimental and numerical analysis results, under different cases, indicated that the joint zone was within the elastic bearing capacity. Buckling failures appeared in the upper or lower tubes. Then parametric studies were carried out to study different factors that may have influence on the ultimate load. Axial load distribution among the four lower tubes in the joint was also analysed. Finally, some joint design recommendations were proposed.

Collapse simulations of a long span transmission tower-line system subjected to near-fault ground motions

Observations from past strong earthquakes revealed that near-fault ground motions could lead to the failure, or even collapse of electricity transmission towers which are vital components of an overhead electric power delivery system. For assessing the performance and robustness, a high-fidelity three-dimension finite element model of a long span transmission tower-line system is established with the consideration of geometric nonlinearity and material nonlinearity. In the numerical model, the Tian-Ma-Qu material model is utilized to capture the nonlinear behaviours of structural members, and the cumulative damage D is defined as an index to identify the failure of members. Consequently, incremental dynamic analyses (IDAs) are conducted to study the collapse fragility, damage positions, collapse margin ratio (CMR) and dynamic robustness of the transmission towers by using twenty near-fault ground motions selected from PEER. Based on the bending and shear deformation of structures, the collapse mechanism of electricity transmission towers subjected to Chi-Chi earthquake is investigated. This research can serve as a reference for the performance of large span transmission tower line system subjected to near-fault ground motions.

Comparative Analysis of Davenport Wind Spectrum and Kaman Wind Spectrum in the Towering Structural Design

To the Yangtze River a long-span transmission tower as an example, this paper makes a comparative analysis on the davenport wind spectrum and kaman wind spectrum, using two different wind spectrum calculation of wind-induced response of the structure. Obtained the conclusions that kaman wind spectrum of considering vertical correlation get greater wind-induced response in a large span transmission tower engineering.

Transmission Tower Collapse Analysis with Wind Load Based on LS-DYNA

Large span transmission tower is the lifeline of electricity transmission，Its collapse destroyed will causes adverse to the social and economic effects，The mechanism of the power transmission tower collapsed caused people's attention.The analysis is based on LS-DYNA program，explicit beam161 beam element is adopted to establish the finite element model for transmission towers，Analyses the collapse process of transmission tower and its failure mode with downburst load.

Research on Dynamic Characteristics of Large Span Transmission Tower in Icing Environment

The transmission tower with a big span in the freezing area is very sensitive to climate. When extreme weather approaches, the tower may collapse easily. The dynamic characteristics of transmission tower structure vary under different weather conditions. This paper, taking a 500kV long span tangent tower as the research subject, will demonstrate the dynamic characteristics of such structures when the weight of wires, the icing stiffness of tower structure and the thickness of ice are considered. The results show that icing has a great impact on the dynamic characteristics of the tower structure and it can not be neglected. When the ice is thick, the contribution of icing to the stiffness of the structure should be considered. This conclusion can provide a reference for the analysis and design of similar towers in high altitude area.

Seismic Performance Analysis of Tower Lines System under Multiple Support Excitation

In order to determine the calculational model of long span transmission tower structure under the multiple support excitation, tower-lines system are adopted. Seismic Performance of long span transmission tower lines system under Multiple Support Excitation were studied by time history analysis method. The seismic response difference of two kinds of excitation is analyzed from Dynamic Characteristics and the number of dangerous bar. It will offer the theory data for the seismic design of the kind of structure. Through analysis, the seismic response difference of the two kinds excitation is correlative to the apparent velocity; Therefore long span transmission tower structure should be considered the effect of multiple support excitation, otherwise the conclusion will be inclined to conservative or risk. Key words: tower lines system; seismic response; time history analysis,multiple support excitation

Rain-Wind-Induced Vibration Control for Long Span Transmission Tower

In this paper, multiple tuned liquid dampers control for rain-wind-induced response of long span transmission tower is investigated. Equations of motion for a structure-TLD system are derived. According to the mechanism of vibration control, rain-wind-induced vibration control for tower model with multiple tuned liquid dampers is carried out by using numerical simulation. Three-dimensional finite element model of tower based on a real project is established. Rain-wind load time history is simulated based on wind and rain theory. Time history curves and the maximum responses without and with tuned liquid damper under rain-wind excitation are analyzed and discussed. The results show that the tuned liquid damper could decrease the rain-wind-induced response of long span transmission tower, and the device could be installed in tower when the response too large.

Dynamic Response analysis of Long Span Transmission Tower under Tornado

To study the effects of tornado on long span transmission tower, a model of the tower is built and the features of the tornado are considered. Three different wind cases are discussed in dynamic analysis with finite element method. The analysis results show that dynamic response is more significant at 45° wind direction.

Dynamic Response analysis of Long Span Transmission Tower under Tornado

To study the effects of tornado on long span transmission tower, a model of the tower is built and the features of the tornado are considered. Three different wind cases are discussed in dynamic analysis with finite element method. The analysis results show that dynamic response is more significant at 45° wind direction.

Study on Long Span Transmission Tower’s Typical Malfunctions

In this paper, several typical malfunctions of the long span transmission tower are analyzed, such as the material stiffness reduced by atmospheric corrosion over a long time, the loose of bolt joint caused by accidental factors or man-made sabotages, and foundation settlement. And establish finite element models according to the characteristics of different malfunctions. By analyzing the models, we discuss the safety of the long span transmission tower at different malfunctions. It is shown that the proposed method is of efficiency and practicality.