[REQUEST] Scitation and Sciencedirect/Elsevier JOURNAL

[ssobhan]

Here get these;
1. Effect of icing on the free vibration of guyed antenna towers
2. Evaluation of non-linear analysis of guyed antenna towers

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[giguni]

Dear members I need these papers:

Y-GUI: A Graphical user interface and pre-processor for the combined finite-discrete element code, Y2D, incorporating material heterogeneity.
Computers & Geosciences, Volume 36, Issue 2, February 2010, Pages 241-252.

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Joint inversion of high-frequency surface waves with fundamental and higher modes
Yinhe Luo et al.
Journal of Applied Geophysics
Volume 62, Issue 4, August 2007, Pages 375–384

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thanks in advance

regards.

[ssobhan]

Dear giguni
here get these;
Y-GUI: A Graphical user interface and pre-processor for the combined finite-discrete element code, Y2D, incorporating material heterogeneity

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Joint inversion of high-frequency surface waves with fundamental and higher modes

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[apocalipse]

Dear members I need these paper:

Modelling of steel lattice tower angle legs reinforced for increased load capacity

Authors:
Yan Zhugea, , , Julie E. Millsb, Xing Mab


Abstract
As a result of changes in design code requirements for wind loads, increased demand for electrical power, and the growing communication industry, retrofitting of existing steel lattice towers has become an important strategy in the transmission tower industry. At present there are two main reinforcing methods that are used in practice for lattice transmission towers. The first method involves adding a number of horizontal braces (diaphragms) to the mid-length of slender, inadequately braced members along the height of the tower; while the second method is focused on strengthening the capacity of the existing legs only by retrofitting them with additional members. In this paper, the most effective leg retrofitting method has been investigated through an experimental testing program using a one-panel angle leg retrofitting model and a nonlinear finite element (FEM) model. A 3D continuum element was developed to model the panels and bolted connections and the results are compared with those obtained from experiments, with good agreement. The model was then simplified using a simple locking system where a special technique was developed to simulate the bolt slip, which was found to be a critical issue from the experiments. The simplified model can then be extended to multi-panel modelling

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thanks and regards
apocalipse

---

Dear members I need these paper:

In-plane dynamic interaction between a tower and conductors at lower frequencies

Authors:
Shigehira Ozono , Junji Maeda

Abstract
Transmission line system can be represented by several analytical models composed of towers and conductors. The contribution of normal modes of a conductor to the dynamic tension force transmitted to a tower is obtained by using a frequency response function of tensions devised for the coupled systems. The in-plane dynamic interaction between a tower and conductors is investigated with varying support stiffness. A representation of the mechanism of the in-plane free vibration of transmission line systems is proposed which covers a wide frequency range.

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thanks and regards
apocalipse

[apocalipse]

Dear members I need these paper:

Analytical study on wind-induced vibration of power transmission towers

Authors:
H. Yasuia, H. Marukawaa, Y. Momomuraa, T. Ohkumab

Abstract
This paper describes a method for analyzing wind-induced vibrations of power transmission towers coupled with power lines and the results of two case studies. It also discusses the influence on response characteristics of differences in transmission support systems and differences between peak factors, computed from a time -series and from power spectrum density. The results of this study show that differences in the way power transmission towers support power lines have an influence on response characteristics, and peak factors computed from a time-series response are greater than those computed from power spectrum density.

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thanks and regards
apocalipse

---

Dear members I need these paper:

Dynamic analysis of guyed towers

Authors:
N. Ben Kahla

Abstract
A model is presented for the dynamic analysis of guyed towers. The model employs a numerical integration method together with an iterative procedure to allow computation of the displacements and internal forces at each node defined on the structure. The dynamic analysis of a guyed tower modelled as a guyed equivalent beam-column has been illustrated with two examples. Frequencies and mode shapes have been determined for both vibration about the structure undeflected position (no wind) and about its deflected position under average wind speed. Dynamic amplification factors for tension time histories at different nodes were computed as a function of variable wind frequencies. The possibility of galloping has been demonstrated even though no current node procedure addresses the problem.

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thanks and regards
apocalipse

[Badis]

to apocalipse
paper#1

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paper#2

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paper#3

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paper#4

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[giguni]

Generation of a pseudo-2D shear-wave velocity section by inversion of a series of 1D dispersion curves

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Pseudospectral modeling and dispersion analysis of Rayleigh waves in viscoelastic media

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Thanks in advance

[lisine]

Generation of a pseudo-2D shear-wave velocity section by inversion of a series of 1D dispersion curves

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Pseudospectral modeling and dispersion analysis of Rayleigh waves in viscoelastic media

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[apocalipse]

Dear members I need these papers:

A simplified model for buckling mechanism in lattice structures

Authors:
R.W. Hopkins, J.L. Meek, F.A. Al-bermani

Abstract
This paper presents a simplified model of buckling mechanism which occurs in slender steel column elements under compressive axial loading. This model has been used to predict buckling capacities of certain structures, and comparisons have been made with test results. The method presented is not as accurate as the current finite element methods which use complete large displacement elasto-plastic analysis. However, it provides a reasonable upper bound load very economically, and with reasonable accuracy. It will be argued that it is pointless striving for a 1% accuracy when material parameters and load target values themselves can only be accurate to, say, 10%. The study has used software developed by Meek [3DBUCKLE—eigenvalue analysis program for buckling of steel columns, University of Queensland (1973)], which uses eigenvalue analysis by iteration to determine the Euler (theoretical) value of the buckling load of a column structure. This program was adapted to include the possibility that, during buckling, a reduced modulus section develops at the central portion of the critical column length. The reduction in the second moment of area of the section over a given length ensures that the revised estimate of the failure load is less than that predicted by the Euler formula for the undamaged column. The program was used to predict the failure loads of structures previously tested in other research programs, and the results show reasonable agreement with experiment. The paper shows the potential of the method as a simple design tool.

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Failure analysis on collapsed towers of overhead electrical lines in the region Münsterland (Germany) 2005

Authors:
C. Klinger, , M. Mehdianpour, D. Klingbeil, D. Bettge, R. Häcker, W. Baer


Abstract
End of November 2005 strong south-west wind and heavy snowfall were predominant in the region Münsterland, north-western part of Germany. This led to accretion of a considerable quantity of wet snow to overhead electrical lines in form of snow rolls on the conductors. Eighty-two transmission towers failed catastrophically, most of them by buckling, however some by brittle fracture. As a consequence nearly 250,000 people have been cut off from electrical power supply for several days with major media attention.

This paper describes the forensic analysis in order to investigate the failure cause. Therefore extensive materials investigations, mechanical testing of original components and specimens thereof, estimations for the real wind and snow loads and their combinations, structural analyses as well as detailed evaluations on the basis of previous investigations, literature and regulations were conducted. It was revealed that some of the examined components were manufactured from Thomas steel which was partially in embrittled condition. The investigated towers fulfilled the design codes valid at the time of erection. However the present line loads of the wet snow rolls on the conductors exceeded by far the ones given in the design codes valid at that time.

The load case leading to failure was reconstructed by the derived positions of loads mainly caused by unequal and asymmetric distribution of snow rolls on left and right electrical system. The loads and corresponding stresses acting on the structure before failure were estimated. By comparison with the fracture forces from mechanical testing of original members of the collapsed tower the component that primarily failed was localised. The primary fracture occurred on a diagonal member under tension made of Thomas steel which was weakened by embrittlement. The failure cause was a combination of heavy weather conditions (storm, approx. 0 °C and wet snowfall leading to heavy snow rolls on conductors), asymmetric loading conditions and the usage of Thomas steel which was partially embrittled. Finally, recommendations for avoiding future failures are given.

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Investigation of transmission line tower failures

Authors:
N. Prasad Raoa, G.M. Samuel Knighta, N. Lakshmananb, Nagesh R. Iyerb

Abstract
This paper presents different types of premature failures observed during full-scale testing of Transmission line towers at Tower Testing and Research Station, Structural Engineering Research Centre, Chennai. Failures that have been observed during testing are studied and the reasons are discussed in detail. The effect of non-triangulated hip bracing pattern and isolated hip bracings connected to elevation redundants in ‘K’ and ‘X’ braced panels, on tower behaviour are studied. The tower members are modeled using beam-column and plate elements. Different types of failures are modeled using finite element software and the analytical results and the test results are compared with various codal provisions. The non-linear finite element analysis program NE-NASTRAN has been used to model the elasto-plastic behaviour of towers. Importance of secondary member design and connection detail in overall performance of the tower was studied. Non-linear finite element analysis is useful in understanding the system behaviour and for prediction of failure pattern and ultimate load. Based on the test results the importance of studying the failures is highlighted. The need for testing of transmission line towers is emphasized.

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Finite element modeling of transmission line under downburst wind loading

Authors:
A.Y. Shehataa, A.A. El Damattya, , , E. Savoryb

Abstract
Despite the fact that extensive research has been carried out on transmission lines subjected to normal wind loads, their behaviour under high intensity wind loads (HIW), such as downburst, is poorly defined. This paper describes a detailed numerical model that can be used to predict the structural performance of a transmission towers as part of a transmission line system under downburst loading. The time history of the downburst wind data is based on a previously developed and validated computational fluid dynamic model. The procedure used to scale the velocity wind data and to transform them to forces is described. Three-dimensional linear elastic frame elements are used to model the members of the towers while two-dimensional curved beam elements with geometric non-linearity included are used to model the conductors and the ground wires. A transmission line that suffered previously from significant damage due to a downburst event is then considered as a case study. Comparison between the results of the downburst analysis and those due to a normal wind that are typically used in the design reveals the importance of considering HIW loads when attempting the structural design of transmission towers.

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Wind response analysis of a transmission tower in a mountainous area

Authors:
Toshinaga Okamuraa, , Takeshi Ohkumab, Eijiro Hongoc, Hajime Okadad

Abstract
Since 1991, the authors have been observing wind in a mountainous area and wind responses of a large power transmission tower constructed in this area. The purpose of these observation is to clarify the wind characteristics and wind responses of power transmission towers. This paper describes the wind characteristics and the wind responses of this transmission tower obtained from full-scale measurements. A wind tunnel test was also conducted on a two-dimensional mountain to investigate the flow around it. Finally, a wind response analysis was conducted on the transmission tower on the basis of these examinations. The wind response analysis results for the blow-down flow on the leeward slope of the mountain corresponded closely with the measurements. This shows that the evaluation of the blow-down angle is also important in the wind response analysis of the transmission tower in the mountainous area.

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Design of angle trusses by codes and second-order analysis with experimental verification

Authors:
Man Fong, Suk-Han Cho, Siu-Lai Chan,

Abstract
Popular national design codes provide varied buckling formulae for design of trusses composed of angle members under different end conditions. The reliability of these design methods highly depends on the accuracy in estimating the effective length, slenderness modification equations and the interaction equations. To date, design method using the second-order analysis has become popular because it captures directly the behavior in analysis and eliminates the error in a linear analysis and design such as assumption of the effective length factor. In this paper, the predicted failure loads of the angle trusses by different codified method would be compared with test results. Further, a refined second-order analysis method is proposed here to the design of angle trusses composed of single angle members with accuracy verified by comparing the predicted and the test results.

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Single-equation yield surfaces for monosymmetric and asymmetric sections

Authors:
S. Kitipornchai, K. Zhu, Y. Xiang, F.G.A. Al-Bermani

Abstract
Single-equation yield surfaces are presented for channel, tee, single-and double-angle sections under combined axial force and biaxial moments. The equations give very good approximations to the accurate yield surfaces while maintaining smoothness, convexity and continuity requirements in three-dimensional space. The equations derived may be implemented in an elasto-plastic analysis program for modelling the nonlinear global behaviour of steel frame structures comprising one or more of these types of section.

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thanks and regards
apocalipse

[Badis]

to apocalipse

the 7 papers compressed in one rar file

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