Civil Engineering Association

1. Ductile knee braced frames with shear yielding knee for seismic resistant structures
2. Preliminary studies into the behaviour of knee braced frames subject to seismic loading
3. Pushover tests on steel X-braced and knee-braced RC frames
4. Seismic behaviour factor, R, for steel X-braced and knee-braced RC buildings

5. Evaluating response modification factors of concentrically braced steel frames

6.Non-linear analysis of disposable knee bracing

Progressive collapse analysis of seismically designed steel braced frames:

Dear members,

I am looking for the following papers:

Geometric and material non-linear behaviour of beam-columns

Authors:
J.L. Meek, S. Loganathan

Abstract:
The present study is concerned with the geometric and material non-linear behaviour of space frame structures comprising thin walled circular and square hollow sections. For the realistic prediction of the non-linear behaviour of a structure, the numerical analysis must incorporate the effect of both geometric and material non-linearities. A simple and efficient formulation of beam-column elements for the large displacement analysis of elasto-plastic frame structures is presented. An incremental-iterative method based on the arc length method combined with the Newton-Raphson method was employed for the solution of the non-linear governing equations. Iterations were not suppressed at any stage of the present scheme. The simplicity, accuracy and efficiency of the proposed method is demonstrated through various numerical examples.



Design of circular and rectangular hollow section columns

Author:
K.S. Virdi

Abstract
An analytical method for computing the ultimate failure loads of inelastic columns subjected to axial thrust and uniaxial bending moments is presented. As part of the computational procedure, a rapid method of calculating the moment thrust curvature relations is described. The procedure uses the well known Gauss quadrature formulae. With the aid of a mapping device, any quadrilateral part of the cross-section can be considered including any arbitrary residual stress pattern. This enables the analysis of a wide variety of cross-sections, including circular and rectangular hollow sections. The ultimate failure loads are obtained by finding the highest load for which an equilibrium deflected shape can be calculated. A generalised Newton-Raphson method has been adopted for the calculation of the deflected shape of the column. The computer program developed has been used to examine the validity of the newly proposed design curves in ECCS Recommendations as well as he draft BS 5400 : Part 3 applicable to circular and rectangular hollow sections. it is concluded that the ECCS recommendations are safe, but the proposals in BS 5400 : Part 3 are found to be unduly conservative.



Geometric and material nonlinear analysis of structures comprising rectangular hollow sections

Authors:
S. Kitipornchai∗, F.G.A. Al-Bermani

Abstract:
This paper presents a nonlinear finite element analysis of structures comprising thin-walled rectangular hollow sections. Nonlinearities due to both the change of geometry and material yielding are included, incorporating also the effects of strain-unloading. The geometry and the stiffness of the elements are modified and used to update the structure tangent stiffness matrix. An iterative numerical procedure combining the arc-length and the work methods is employed for the solution of the incremental equation of equilibrium. The method has been applied successfully to predict the nonlinear load-deflection behaviour of isolated cold-formed SHS columns, fabricated RHS parabolic fixed end arches, and double chord SHS trusses having different joint configurations.



Geometrically nonlinear analysis of elastic framed structures

Authors:
M.B. Wong, F. Tin-Loi

Abstract:
The development of a method for the elastic nonlinear analysis of framed structures is presented. It is capable of providing solutions up to and including any existing limit point. The effects of both member and structure deformations are accounted for. The solution strategy proposed rests on a judicious combination of the well-known Newton-Raphson iterative scheme and a novel modification of the arc-length method within a finite element based partially updated Lagrangian description. The proposed variation of the arc-length technique enables a solution at the limit point to be calculated. Very accurate results can be obtained as demonstrated by three examples, all solved using the computer program developed.



Nonlinear analysis of lattice structures

Authors:
S. Kitipornchai, F.G.A. Al-Bermani

Abstract:
The paper describes a nonlinear analytical technique developed by the authors in recent years for predicting the structural response of large scale lattice structures. This type of structure is generally more sensitive to imperfections; hence, the analysis method needs to consider the various nonlinear effects. Sources of nonlinearity affecting the ultimate behaviour of lattice structures include geometric nonlinearity, material nonlinearity, joint flexibility and slippage. Geometric nonlinearity can be accounted for by incorporating the effect of initial stress as well as geometrical variations in the structure during the loading process. For large scale lattice structures, the material nonlinearity can be incorporated by using the lumped plasticity model, while the effect of joint flexibility can be incorporated by modifying the tangent stiffness of the element using an appropriate moment—rotation relation for the joint. The nonlinear formulation has been applied to a number of example problems selected to demonstrate the applicability and versatility of the method.



Advanced analysis of steel building frames

Authors:
M.J Clarke, R.Q Bridge, G.J Hancock, N.S Trahair

Abstract
The paper describes advanced analysis as defined in the Australian limit states design specification, AS 4100-1990. Advanced analysis may be used for the second-order inealstic analysis and design of frames in which the members are compact and have full lateral restraint. Some aspects of the inclusion of residual stresses, geometrical imperfections and capacity factors in advanced analysis are discussed. An advanced analysis based on the finite element method and utilising a distributed plasticity formulation has been developed at the University of Sydney and is used to perform numerical studies of the behaviour of simple structural elements and frames, including the effects of residual stresses and geometrical imperpections. Based on the results of the analyses, some observations on the importance of including imperfections in the advanced analysis of steel building frames are made.



Performance of tuned mass dampers under wind loads

Author:
K.C.S. Kwok

Abstract
The performance of both passive and active tuned mass damper (TMD) systems can be readily assessed by parametric studies which have been the subject of numerous research. The results of those parametric studies are invaluable in the selection of optimum TMD parameters. Few experimental verifications of TMD theory have been carried out, particularly those involving active control, but the results of those experiments generally compared well with those obtained by parametric studies. Despite some serious design constraints, a number of passive and active tuned mass damper systems have been successfully installed in tall buildings and other structures to reduce the dynamic response due to wind and earthquakes. The results of extensive full-scale measurement programs conducted on a significant number of these clearly show the effectiveness of the systems.



The Effect Of Shear Deformation On The Critical Buckling Of Columns

Authors:
J.R. Banerjee, F.W. Williams

Abstract:
Starting from equations analogous to those that are widely used for vibration of axially loaded Timoshenko beams, insights are obtained into the buckling behaviour of columns which deform in shear. These insights help in explaining and recognizing those combinations of end conditions for which a simple formula, originally derived by Engesser for clamped-free columns, can be used to predict exactly the effect of shear deformation on the lowest critical buckling loads of columns. The formula is Pc = P0 /(1 + P0/kAG), where Pc is the required buckling load, P0 is the buckling load if shear deformation is ignored and kAG is the shear rigidity. Illustrative results are given for metal columns, but these are intended primarily as an introduction to the principal result. This consists of a single curve which can be applied to metal or composite columns. It represents Engesser's equation, and is expressed in terms of the effective length ratio of the column obtained by ignoring the shear deformations. The combinations of end conditions for which this curve is valid are explored and it is shown to be valid for many standard cases, including hinged-hinged, clamped-free and clamped-clamped columns. It is also valid if the hinged-hinged column has rotational springs of equal stiffness added at its ends. However, the curve is not valid for the common clamped-hinged case (or if the hinged-hinged column has rotational springs of unequal stiffnesses at its ends) for which it can give 20% or greater discrepancy from the correct curve. Such large differences occur in ranges which are of relevance for many composite columns, which is the context in which the results presented are expected to be most useful.



An interactive buckling theory for built-up beam-columns and its application to centrally compressed built-up members

Authors:
Tong Geng-Shu, Chen Shao-Fan

Abstract
By modelling the built-up beam-column as a member with a sandwich cross-section and introducing the concept of reduced axial stiffness of an imperfect bar, this paper establishes an interactive buckling theory for built-up beam-columns which can be used to determine the ultimate strength of the member taking account of various adverse influences of imperfections (residual stress, member's and chords' initial deflections and load eccentricity).

A centrally compressed built-up column is analysed by the Finite Integral Method to illustrate the application of the theory. It is found that the chord's critical stress is the upper limit of the column's critical stress and can be used as the ‘compressive yield stress’ of the column; there exists a very unfavourable interaction between the bending of the chord and of the column. A Q-factor design method similar to that adopted in cold-formed steel is suggested for the built-up column. A simple shear force formula is presented which is in reasonable agreement with the current available test results.


regards,
apocalipse

Dear apocalipse,

All the requested papers:

Dear members,

I am looking for the following papers:

Digital simulation of random processes and its applications

Authors:
M. Shinozuka and C.-M. Jan

Abstract:
Efficient methods are presented for digital simulation of a general homogeneous process (multidimensional or multivariate or multivariate-multidimensional) as a series of cosine functions with weighted amplitudes, almost evenly spaced frequencies, and random phase angles. The approach is also extended to the simulation of a general non-homogeneous oscillatory process characterized by an evolutionary power spectrum. Generalized forces involved in the modal analysis of linear or non-linear structures can be efficiently simulated as a multivariate process using the cross-spectral density matrix computed from the spectral density function of the multidimensional excitation process. Possible applications include simulation of (i) wind-induced ocean wave elevation, (ii) spatial random variation of material properties, (iii) the fluctuating part of atmospheric wind velocities and (iv) random surface roughness of highways and airport runways.



Digital simulation of environmental processes with respect to fatigue

Authors:
M. Bílý, J. Bukoveczky

Abstract:
To estimate the service fatigue life of dynamically loaded components and structures, fatigue tests with simulated loads must be carried out. This paper presents various methods of on-line digital simulation of real environmental processes, representing inputs of fatigue machines. According to the method of analysis adopted, this simulation can be based either on sinusoidal amplitudes in the form of blocks or individual cycles, or on random processes. The random process simulation can reproduce the probability density of amplitudes, the power spectral density, or both of them, depending on the fatigue damage hypothesis and philosophy of testing accepted.


On the normality and accuracy of simulated random processes

Author:
J.-N. Yang

Abstract
Efficient methods of simulating stationary and non-stationary random processes and envelopes, by using a series of sine or cosine functions or by using the fast Fourier transform, have been proposed previously. Without applying the central limit theorem, it is shown in this paper that the simulated random processes are asymptotically Gaussian processes as the number of terms, N, of sine or cosine functions approaches infinity. The accuracy of the first-order probability densities of the simulated random processes is investigated by using the fast Fourier transform. Numerical results are computed with respect to the variation of the number of terms, N, of sine or cosine functions used for simulation. It is shown that within the practical range of N, such as 500, the accuracy is remarkably satisfactory even outside the region of 3 standard deviations. The investigation of the accuracy of the second-order probability densities by applying the fast Fourier transform is also described in detail. The study of accuracy presented herein is of vital importance in determining the applicability and practicality of methods of simulation.



3 – Simulation of Random Processes



RANDOM PROCESSES



Practical experiences with wind-induced vibrations

Author:
H. Ruscheweyh

Abstract
A refined engineering model for the estimation of vortex-induced vibrations slender stuctures is briefly presented. Experiences with this model in relation to full-scale observations are shown within three different examples. The first example is related to steel stacks, the second describes the experience with bridge hangers and its modification by aerodynamic devices. The third example shows the failure of a steel bridge bracing by vortex-induced vibrations and the increase of damping with dynamic vibration absorbers.


regards,
apocalipse

1. Digital simulation of random processes and its applications


2. Digital simulation of environmental processes with respect to fatigue


3. On the normality and accuracy of simulated random processes


6. Practical experiences with wind-induced vibrations

• Article/eBook Full Name: Study on elephant-foot buckling of broad liquid storage tanks by nonlinear theory of shells
  
• Author(s): Min Zhou,
  
• Publish Date: 1992
  
• Published By: ELSEVIER
  
• Related Links:
  
  
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Dear ssobhan,

Study on elephant-foot buckling of broad liquid storage tanks by nonlinear theory of shells

Dear members,

I need the following papers:

Gust buffeting and turbulence uncertainties

Authors:
Luisa Carlotta Pagnini, Giovanni Solari

Abstract:
Literature on turbulence modeling is rich in empirical, semi-empirical and theoretical spectral equations whose parameters assume deterministic values. Starting from a critical review of the state of the art, a unitary model of the 3-D atmospheric turbulence was proposed where all parameters are defined by first- and second-order statistical moments derived from a wide selection of experimental measurements. Analyses based on Monte Carlo simulation of the model parameters show that the propagation of turbulence uncertainties over the wind-excited response of structures gives rise to a relevant scatter. The passage from Monte Carlo simulations to Taylor series expansions addressed to apply the first-order second-moment technique provides systematic rules to deal with the structural response in a full probabilistic environment. It also allows appreciation of the role of each uncertain parameter. The joint application of this procedure and a closed form solution of the response drastically reduces the computational burden and makes these analyses operatively possible. The proposed approach is a step forward towards the formulation of a unitary probabilistic model of the wind-excited response of structures, comprehensive of model errors, parameter uncertainties and parameter randomness.



Fatigue analysis of roof cladding under simulated wind loading

Authors:
K. Suresh Kumar, T. Stathopoulos

Abstract
Several damage mitigation studies have concluded that wind-induced fatigue may be responsible for the extensive damage to roof cladding. This paper presents the application of the recently proposed novel simulation methodology, capable of generating both Gaussian and non-Gaussian wind pressure fluctuations, in the fatigue analysis of roof cladding. After establishing the simulated fatigue characteristics of roof pressures, the total fatigue loading has been estimated by integrating the long-term wind climate with the simulated fatigue characteristics of roof pressures. Simulated results are compared with predictions made by Rayleigh, Gaussian and Weibull models as well as German and British recommendations. The study indicates that non-normality can significantly increase the rate of fatigue damage accumulation, and, if neglected, it can result in non-conservative fatigue life estimates.



Fatigue life estimation of steel girder of Yangpu cable-stayed Bridge due to buffeting

Authors:
M Gua, Y.L Xub, L.Z Chena, H.F Xianga

Abstract:
As the main span of modern cable-stayed bridges becomes longer and longer, the buffeting-induced fatigue damage problem of steel girders located in strong wind regions may have to be taken into consideration in the design of the bridge. This paper presents a method in the mixed frequency–time domain for estimating the fatigue life of steel girders of the Yangpu cable-stayed Bridge due to buffeting. In the suggested method, the joint probability density function of wind speed and wind direction at the deck level of the bridge is first established. The power spectra of the critical stress of the girder are then derived from the power spectra of the generalized coordinates of the bridge for different wind speeds and wind directions. The derived stress spectra are no longer a narrow spectrum when the background component of stress response is included. Thus, the time histories of the critical stress are simulated from their power spectra and the stress cycle distributions are estimated in terms of rainflow count method. The formulae derived based on the modified Miner law and the random vibration theory are finally used for estimating the fatigue life of the bridge girder. The results show that the effects of wind direction on the fatigue life of the Yangpu Bridge are significant. The predicted fatigue life due to buffeting is much longer than the design life of the bridge.


regards and thanks,
apocalipse

@apocalipse

Here you go

Gust buffeting and turbulence uncertainties



Fatigue analysis of roof cladding under simulated wind loading


Fatigue life estimation of steel girder of Yangpu cable-stayed Bridge due to buffeting