共查询到20条相似文献,搜索用时 31 毫秒
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本文利用虚功原理,基于修正的拉格朗日列式,得到桅杆结构增量形式的非线性有限元动力方程。在此基础上,以地震波为激励,计算了桅杆结构受地震作用的非线性位移、加速度动力响应,并对桅杆结构在纤绳初应力变化下的抗震性能进行了分析。 相似文献
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S. Ali Ghafari OskoeiGhyslaine McClure 《Engineering Structures》2011,33(5):1764-1772
Telecommunication structures are essential components of communication and post-disaster networks and critically important facilities require reliable earthquake-resistant design procedures in seismically active regions. Calculation of the nonlinear seismic response of tall guyed masts using detailed time-step finite element methods is far more complex than linear response spectrum analysis that is routinely used in structural engineering practice. It is recognized that detailed computational procedures are not always necessary, in particular when the goal of the analysis is to provide a global earthquake-resistant design check on a regular structure with predictable response: this is when rational simplified methods are called upon to calculate the seismic demand. However, up until now, no such method exists for tall guyed masts that can account for the dynamic cable-mast interactions which dominate seismic effects in these structures. In the study reported here, the writers explore the dynamic behavior of guy cables under harmonic and seismic support ground motion through detailed computational modeling and propose a novel frequency-dependent method to evaluate the equivalent dynamic stiffness of guy clusters. This development will contribute efficiently towards a new robust rational model of general applicability for simplified seismic analysis of tall guyed telecommunication masts.Detailed numerical simulations involving 57 guy cables from eight existing towers with varying heights of 150-607 m were used in the study. A mathematical procedure was developed to replace the nonlinear time-variant cable stiffness with an equivalent linear frequency-dependent spring/mass system, based on the response spectrum of individual guy cables and the frequency content of the seismic excitation. Comparison of the main response indicators of these equivalent models and the detailed nonlinear finite element analysis results confirmed the reasonable and consistent engineering accuracy of the proposed simplified method with considerable savings in analysis effort. 相似文献
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Ahmet Can Altunişik Alemdar Bayraktar Barış Sevim Fatma Birinci 《Civil Engineering and Environmental Systems》2013,30(3):247-259
This research presents finite element modelling, vibration-based operational modal analysis, and finite element model updating of a restored historic arch bridge. Mikron historic bridge, constructed on F?rt?na River in Rize, Turkey, is the subject of this case study. The General Directorate for Highways of Turkey repaired the bridge's main structural elements, arches, sidewalls, and filler material in 1998. To construct a 3D finite element model of the bridge, ANSYS finite element software estimated the analytical dynamic characteristics. Induced ambient vibrations such as human walking and wind excited the model bridge to allow measurement of the bridge's responses. Enhanced frequency domain decomposition in frequency domain and stochastic subspace identification in time domain methodologies extracted experimental dynamic characteristics. A comparison of the analytical and experimental results showed significant agreement between mode shapes, but some differences in natural frequencies appeared. Consequently, updating the finite element model of the bridge by changing boundary conditions minimised the differences between analytical and experimental natural frequencies. After the finite element model updating process, the differences between natural frequencies declined from 7% to 2%. 相似文献
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基于频域的桅杆结构风振疲劳分析 总被引:2,自引:0,他引:2
本文基于随机振动理论对实测的桅杆结构风洞试验数据进行处理,分析了桅杆结构风振响应的频谱特性,并且从频域着手通过简单的数值运算求得足够精确的等效应力用于计算桅杆结构的风振疲劳寿命,避免了雨流点法极大的工作量。 相似文献
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通过研究与思考,提出了两种适用于张拉索的找形方法,给出了这两种方法的原理与具体实施步骤,并分别以简单索结构和桅杆结构为计算实例进行了验证和比较,有效的解决了桅杆结构的找形问题。 相似文献
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推导了弹性结构体系在任意动力荷载作用下的动力稳定性判别准则,用此准则对实际桅杆结构在随机风载下的动力稳定性进行分析,并在总结桅杆结构动力失稳的特性和规律的基础上,提出了简化的位移判别准则。 相似文献
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为了给桅杆结构的健康监测研究提供一个较为准确的有限元基准模型,采用规划优化算法作为桅杆结构模型修正的基本工具,同时将优化算法与大型有限元分析软件相结合,首先,利用ANSYS软件仿真得到桅杆结构的一组动力响应数据,并将它作为模拟的实测数据,用以作为有限元模型修正的基准。其次,以桅杆结构结构的杆端联结刚度可调的杆件有限元模型为对象,以杆端的节点连接刚度为修正参数,以结构模型的节点位移作为修正目标,建立了目标函数从而修正了结构的有限元理论模型。 相似文献
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基于桅杆结构拉耳表面应变对其焊缝裂纹扩展长度的敏感度分析,提出了桅杆结构拉耳焊缝损伤的两级模糊模式识别方法,并通过试验研究进行验证。采用有限元模拟建立了拉耳索力 关键点应变 焊缝裂纹扩展长度的模糊模式库;对16个不同裂纹长度的拉耳模型进行试验,以实测拉耳表面关键点应变为待识别样本,采用模糊模式识别方法对索力及焊缝裂纹扩展长度进行分步识别。结果表明:模糊数据库中的模拟数据能够反映拉耳的实际受力状态,识别焊缝裂纹扩展长度与实际裂纹长度具有较好的吻合度;对于不同索力及裂纹长度,识别焊缝裂纹扩展长度的误差在1 mm之内,最大隶属度均大于0.8,识别峰值明显;该识别技术具有可行性,是实现桅杆结构损伤智能识别的一种有效手段。 相似文献
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Alemdar Bayraktar Bari Sevim Ahmet Can Altuniik Temel Türker 《The Structural Design of Tall and Special Buildings》2010,19(3):257-273
This paper describes a Turkish style reinforced concrete minaret, its finite element model, modal testing, finite element model updating and earthquake behaviour, before and after model updating. The minaret of a mosque located in Trabzon, Turkey is selected as an application. A three‐dimensional (3D) model of the minaret and its modal analysis is performed to obtain analytical frequencies and mode shapes using ANSYS finite element program. The ambient vibration tests are conducted on the minaret under natural excitations such as wind effects and human movement. The output‐only modal parameter identification is carried out by Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods in Operational Modal Analysis software and in doing so, dynamic characteristics (natural frequencies, mode shapes and damping ratios) are determined. A 3D finite element model of the minaret is updated to minimize the differences between analytical and experimental modal properties by changing some uncertain modelling parameters such as material properties and boundary conditions. The earthquake behaviour of the minaret is investigated using 1992 Erzincan earthquake before and after finite element model updating. Maximum differences in the natural frequencies are reduced from 21% to 8%, and good agreement is found between analytical and experimental natural frequencies. In addition to this, it is realized that finite element model updating is effective on the earthquake behaviour of the minaret. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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He Yan-li Ma XingWang Zhao-min 《Journal of Wind Engineering & Industrial Aerodynamics》2003,91(4):513-525
Based on the idea of the discrete analysis method of random vibration, the paper studied the wind-induced response of guyed masts, the Gaussian close assumption is adopted to close the mean square equations when taking into account the nonlinearity of cables. The wind load is generated from spatially correlated filtered white noise. The discrete random vibration method can calculate accurate mean and mean square responses, the wind responses analysis for a numerical example demonstrate this point, and the results of discrete random vibration method is close to the results of experiment through wind-induced response analysis of a wind tunnel experiment model. 相似文献
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M.J. Lambert M.H. Ogle B.W. Smith 《Journal of Wind Engineering & Industrial Aerodynamics》1988,30(1-3):55-65
This paper describes full scale instrumentation and analysis of tall guyed lattice masts to correlate wind speed and direction with structural stresses, particularly in welds. It outlines a method of predicting residual fatigue life from past meteorological records, where regular inspection is difficult. 相似文献
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Monika Matuszkiewicz 《Engineering Structures》2011,33(6):2044-2048
Selected problems concerning designing of guyed masts with lattice shaft in accordance with the “EN 1993-3-1: Design of steel structures. Part 3-1: Towers, masts and chimneys-Towers and masts” European standard have been described in this paper. The method of application of the mast shaft geometrical imperfections in calculations has been discussed. Based on the performed comparative analysis of a certain mast, the influence of such imperfections on the ultimate values of internal forces in the mast shaft has been demonstrated. 相似文献
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H. Nohutcu A. Demir E. Ercan E. Hokelekli G. Altintas 《The Structural Design of Tall and Special Buildings》2015,24(13):821-834
This paper presents the results of model calibration conducted on a historical mosque called Hafsa Sultan in Manisa, Turkey. The finite element model of the mosque was calibrated by the use of the results obtained from ambient vibration tests of the structure. In order to develop a solid model of the structure, the dimensions of the structure, defects such as cracks and material degradations in the structure, and the materials used in different parts were identified. For the evaluation of the material properties of the structure, nondestructive and destructive testing methods were used. The numerical and experimental modal parameters of the structure were obtained by finite element method (FEM) and Operational Modal Analysis (OMA), respectively. The natural frequencies and corresponding mode shapes were obtained from both FEM and OMA and compared with each other. While a good compatibility was achieved between mode shapes, some differences between natural frequencies occurred. It was thought that the differences resulted from variations in the Young's modulus of masonry, cracks in elements or boundary conditions. Therefore, the finite element model was calibrated by changing material parameters. Finally, a more realistic numerical model of the mosque was put forward and the results were discussed in detail. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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《Journal of Constructional Steel Research》2011,67(12):1912-1921
This paper describes a full scale arch type steel highway bridges, its finite element modelling and Operational Modal Analysis. Eynel Highway Bridge which has arch type structural system with a total length of 336 m and located in the Ayvac?k county of Samsun, Turkey is selected as a case study. The bridge connects the villages which are separated with Suat U?urlu Dam Lake. The three dimensional finite element model is constructed using project drawings and an analytical modal analysis is then performed to generate natural frequencies and mode shapes in the three-orthogonal directions. The ambient vibration tests on the bridge deck under natural excitation such as traffic, human walking and wind loads are conducted using Operational Modal Analysis. Sensitive seismic accelerometers are used to collect signals obtained from the experimental tests. To obtain experimental dynamic characteristics, two output-only system identification methods are employed namely, Enhanced Frequency Domain Decomposition method in the frequency domain and Stochastic Subspace Identification method in time domain. The correlation between the finite element model and experimental results is studied. Good agreement is found between dynamic characteristics in the all measurement test setups performed on the bridge deck. It is demonstrated that the ambient vibration measurements using Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods are enough to identify the most significant modes of steel highway bridges. It is seen that there are some differences between analytical and experimental natural frequencies and experimental natural frequencies are generally bigger than the others. 相似文献