Buckling Research Papers - Academia.edu (original) (raw)

Conventional concentrically braced frame (CBF) systems have limited drift capacity prior to brace buckling, and related damage leads to deterioration in strength and stiffness. CBFs are also susceptible to weak story failure. A... more

Conventional concentrically braced frame (CBF) systems have limited drift capacity prior to brace buckling, and related damage leads to deterioration in strength and stiffness. CBFs are also susceptible to weak story failure. A pinsupported self-centering frictiondamped braced frame system with buckling-restrained columns (FDBF-BRC) is being developed to provide significant drift capacity while limiting damage due to residual drift and soft-story mechanisms. The FDBF-BRC system consists of beams, columns, and braces branching off a central column, with buckling restrained columns (BRCs) incorporated into the system at the first story external column positions. The BRCs and friction generated at lateral-load bearings at each floor level are used to dissipate energy to minimize the overall seismic response of the FDBF-BRC system. Vertically aligned post-tensioning bars provide additional overturning moment resistance and aid in self-centering the system to eliminate residual drift. Th...

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with... more

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright a b s t r a c t One of the most important aspects of the seismic response of elastomeric isolators is their stability under large shear strains. The bearing capacity of elastomeric isolators, indeed, progressively degrades while increasing horizontal displacement. This may greatly influence the design of elastomeric isolators, especially in high seismicity regions, where slender elastomeric isolators subjected to large horizontal displacements are a common practice. In the current design approach the critical load is evaluated based on the Haringx theory, modified to account for large shear strains by approximate correction factors. In this paper the critical behavior of a pair of slender elastomeric devices is experimentally evaluated at different strain amplitudes, ranging from approximately 50% to 150%. The experimental results are then compared to the predictions of a number of semi-empirical and theoretical formulations. The main conclusion of this study is that current design approaches are overly conservative for slender elastomeric seismic isolators, since they underestimate their critical load capacity at moderate-to-large shear strain amplitudes.

The study presents crystal plasticity finite element simulations of cylindrical Cu single crystal micropillar compression tests. The aim is to study the influence of the stability of the initial crystal orientation, sample geometry... more

The study presents crystal plasticity finite element simulations of cylindrical Cu single crystal micropillar compression tests. The aim is to study the influence of the stability of the initial crystal orientation, sample geometry (diameter-to-length ratio) and friction on the anisotropy and crystallographic orientation changes during such tests. Initial anisotropy (initial orientation) has a strong influence on the evolution of crystallographic orientation changes and also, to a minor extent, on the sample shape during compression. Pronounced orientation changes occur at an early stage of compression (at engineering strains of 0.2), entailing as a rule a large orientation spread within the initially uniformly oriented sample. A non-zero friction has a stabilizing effect on the course of the compression test even in cases where strong orientation changes occur. The evolution of orientation changes during compression is in part due to rigid body rotations (shape inclination due to buckling) rather than exclusively to crystallographic reorientation. Orientations that are crystallographically unstable and non-symmetric during compression tend to entail shape instability of the pillars at an earlier stage than observed for more stable cases.

Collapse of pile-supported structures in liquefiable deposits is still observed after strong earthquakes despite the fact that large factors of safety (against bending due to lateral loads and axial capacity) are employed in their design.... more

Collapse of pile-supported structures in liquefiable deposits is still observed after strong earthquakes despite the fact that large factors of safety (against bending due to lateral loads and axial capacity) are employed in their design. Currently, piles in liquefiable soils are designed as beams to avoid bending failure arising from lateral inertial and kinematic (lateral spreading) loads. Recent research suggests that part of the pile in liquefiable soils needs to be treated as unsupported structural columns to avoid buckling instability. Essentially, piles should be treated as columns carrying lateral loads. Beam bending and column buckling require different approaches in design. Designing against bending would not automatically suffice for the buckling requirements. To avoid buckling instability, there is a requirement of minimum diameter of the pile depending on the depth to which the pile may be unsupported owing to liquefaction. In addition, there is also a need to reconside...

An exact solution for buckling of simply supported symmetrical cross-ply composite rectangular plates under a linearly varying edge load is presented. It is developed based on the first-order shear deformation theory for moderately thick... more

An exact solution for buckling of simply supported symmetrical cross-ply composite rectangular plates under a linearly varying edge load is presented. It is developed based on the first-order shear deformation theory for moderately thick laminated plates. Buckling loads of cross-ply rectangular plates with various aspect ratios are obtained and the effects of load intensity variation and layup configuration on the buckling load are investigated. The results are verified using the computer code ABAQUS.

The usage of heterogeneous materials in situations where large strength to weight ratio is required has been increased substantially over the world in all construction aspects. The behaviour of the plate under each loading is different.... more

The usage of heterogeneous materials in situations where large strength to weight ratio is required has been increased substantially over the world in all construction aspects. The behaviour of the plate under each loading is different. Whenever the delamination is located at the middle plane of laminate, the panel exhibits only global buckling, i.e. there is no buckling of delaminated region. Whenever the delamination is close to the surface, the buckling mode is predominantly local. The type of plate also plays a major role in carrying load. This article summarises the numerical study carried out using finite element software ANSYS and Timoshenko's methodology to examine the buckling behaviour of homogeneous and heterogeneous plate element with and without crack. Also the effect of aspect ratio on the buckling behaviour with varying plate thickness for different boundary conditions was also examined.

Compared to traditional prosthetic pylon materials (Aluminum, Titanium, or Stainless steel.), composite prosthetic pylon materials are used instead of metals. Vacuum bagging technique was adopted for the preparation of specimens made of... more

Compared to traditional prosthetic pylon materials (Aluminum, Titanium, or Stainless steel.), composite prosthetic pylon materials are used instead of metals. Vacuum bagging technique was adopted for the preparation of specimens made of Poly methyl methacrylate (PMMA) as matrix with constant Perlon layers and different number of Hybrid (Carbon + Glass) fibers layers as reinforcement materials at (±45º&0º/90º) orientation relative to applied load. Also the finite element method (ANSYS-15) were used by create a model of prosthetic pylon and applied compressive load at heel strike step from gait cycle to known the critical buckling stress. The experimental and numerical results shown that the tensile strength, modulus of elasticity, and critical buckling stress increases with increasing number of Hybrid fibers layers, that equal to (145 MPa, 6.25 GPa, and 670 MPa) respectively, and the percentage of increase in tensile strength, modulus of elasticity, and critical buckling stress for specimen with three Hybrid (Carbon + Glass) layers and Perlon layers in PMMA resin compared with pure PMMA specimen was (302.7% , 300% & 257.22%) respectively, at (0º/90º) fibers orientation relative to tensile force.

Free vibration and stability analysis of axially functionally graded tapered Timoshenko beams are studied through a finite element approach. The exact shape functions for uniform homogeneous Timoshenko beam elements are used to formulate... more

Free vibration and stability analysis of axially functionally graded tapered Timoshenko beams are studied through a finite element approach. The exact shape functions for uniform homogeneous Timoshenko beam elements are used to formulate the proposed element. The accuracy of the present element is considerably improved by considering the exact variations of cross-sectional profile and mechanical properties in the evaluation of the structural matrices. Carrying out several numerical examples, the convergence of the method is verified and the effects of taper ratio, elastic constraint, attached mass and the material non-homogeneity on the natural frequencies and critical buckling load are investigated.

The purpose of the project is to fabricate a Personal Transporter (PT).This vehicle is designed to overcome the cost of the actual Segway Vehicle and to provide zero pollution within the campus or industries and this transporter doesn’t... more

The purpose of the project is to fabricate a Personal Transporter (PT).This vehicle is designed to overcome the cost of the actual Segway Vehicle and to provide zero pollution within the campus or industries and this transporter doesn’t use the gyroscope unit and sensors to keep the vehicle in the flat position, Instead this is achieved by the supporting wheels. The project aims at fabricating a vehicle which can reach a maximum speed of 20kmph (can be programmed up to 50kmph) and travel a distance of approximately 8- 10 kms. The time for which the vehicle runs is roughly 2 hours and vary depending on the speed at which the vehicle travels. The torque and power of the motor and are selected from the various configurations available in the market and which satisfies our requirements also. The wheels used are hub motor type wheels in which the motor is situated inside the hub of the wheel at the center. These wheels are not generally available in India and need to be imported. These wheels require less torque and power when compared to motor driving the wheel. The input to the wheel is given through an accelerator and is controlled using an electronic controller. Brakes can be applied to any wheel and turning the vehicle can be done by applying brakes on any of the side required depending on the direction of turn to be taken. For the vehicle to stop completely both the brakes need to be applied.

The goal of the present research is the distortional-global (D-G) buckling interaction of cold-formed steel (CFS) lipped channel (LC) columns, in its buckling, structural behavior and strength nature. Some studies on this topic have been... more

The goal of the present research is the distortional-global (D-G) buckling interaction of cold-formed steel (CFS) lipped channel (LC) columns, in its buckling, structural behavior and strength nature. Some studies on this topic have been conducted in the literature, however, the D-G interaction is not well known and needs more attention.
For an elastic buckling analysis, a software entitled FStr Computer Application Program is developed. The application is based on the Finite Strip Method, mainly focused in a simple and accessible interface. The FStr program generates the modal shapes and insert as initial geometric imperfections in the finite element software ANSYS, in order to perform a geometric and material nonlinear analysis. Both, the FStr program and the finite element model are validated with available numerical examples and laboratory tests from the literature. Moreover, for the structural behavior and column strength, it is carried out stability paths from previous nonlinear analysis, for different combination of initial geometric imperfection of global and distortional modes. The buckling mode combination as initial geometric imperfection helps to understand the D-G buckling interaction, which is difficult to predict with a simple elastic buckling analysis. The results of the initial imperfection combination have shown that, for high yielding steel, the global initial geometric imperfection provides the most detrimental ultimate load. Additionally, a parametric study varying the column’s length have shown that the nominal axial strength for global buckling equation, already in the standards, is enough to cover the DG coupled phenomenon.

This paper is the first in a series of articles published in the Permanent Way Institution - Journal, intended to present complementary information to what is currently available in the formal continuous welded rail (CWR) training courses... more

This paper is the first in a series of articles published in the Permanent Way Institution - Journal, intended to present complementary information to what is currently available in the formal continuous welded rail (CWR) training courses and UK Standards and discuss the general principles and theoretical considerations on railway track which is subjected to thermal effects. These can be used by Track Engineers for a better understanding of the physics behind the rails’ behaviour when subjected to temperature variations and can also help understanding the specifications and requirements mandated in the current standards covering the management of jointed respectively CWR track. Multiple thermal force diagrams will be presented for both jointed track and CWR applications. This first article is presenting general principles and theoretical considerations on the rails affected by thermal variation.

Linear buckling analysis, which is also called eigenvalue approach, is able to predict the theoretical critical buckling load. This method is used for Finite Element Analysis and also in compliance with theoretical methods in solid... more

Linear buckling analysis, which is also called eigenvalue approach, is able to predict the theoretical critical buckling load. This method is used for Finite Element Analysis and also in compliance with theoretical methods in solid mechanics or theory of plates and shells. Material behaviour is completely elastic for this type of analysis and will be processed based on solving eigenvalue problem. This paper presents a finite element model for a circular plate with fixed edge and simply supported edge as two different boundary conditions. The study uses ABAQUS (Student Edition 2019) software to derive the finite element model of the circular plate. The results obtained through FEM would be compared with an exact solution for both boundary conditions.

Weight reduction is an important topic in aviation industry, as in many areas of engineering. Meanwhile the weight reduction is significant, some forces acting on the materials bring engineering challenges to field such as having less... more

Weight reduction is an important topic in aviation industry, as in many areas of engineering. Meanwhile the weight reduction is significant, some forces acting on the materials bring engineering challenges to field such as having less weight with a good durability. For panels those are used in aviation industry and specifically on the wings of the planes have the same difficulty. Buckling failure can occur as a result of compressive forces acting on wings and it threatens flight safety. In the light of recent technological developments, integrally stiffened plates become more utilizable than riveted stiffened plates. Usage of integrally stiffened plates prevents unnecessary labour and problems caused by riveted connections. In this study, nonlinear buckling analysis of riveted and integrally stiffened plates were examined. As a result, integrally stiffened plates that are lighter in weight and have higher ultimate buckling load compared to the riveted plates were obtained.

This work experimentally and numerically studies large deflection of slender cantilever beam of linear elastic material, subjected to a combined loading which consists of internal vertical uniformly distributed continuous load and... more

This work experimentally and numerically studies large deflection of slender cantilever beam of linear elastic material, subjected to a combined loading which consists of internal vertical uniformly distributed continuous load and external vertical concentrated load and a horizontal concentrated load at the free end of the beam. We got equations with the help of large deflection theory, and present the differential equation governing the behaviour of this system and show that that this equation, although straightforward in appearance, is in fact rather difficult to solve due to the presence of a non-linear term. A numerical evaluation is used to evaluate the system and calculate Young`s modulus of the beam material. With simple experiment we show, how a Young`s modulus can be obtained and then the phenomenon of the large elastic sideways deflection of a column under compressive loading is investigated and elastica of buckled column is calculated.

Lightweight thin-walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi-empirical models. An... more

Lightweight thin-walled cylindrical shells subjected to external loads are prone to buckling rather than strength failure. The buckling of an axially compressed shell is studied using analytical, numerical and semi-empirical models. An analytical model is developed using the classical shell small deflection theory. A semi-empirical model is obtained by employing experimental correction factors based on the available test data in the theoretical model. Numerical model is built using ANSYS finite element analysis code for the same shell. The comparison reveals that the analytical and numerical linear model results match closely with each other but are higher than the empirical values. To investigate this discrepancy, non-linear buckling analyses with large deflection effect and geometric imperfections are carried out. These analyses show that the effects of non-linearity and geometric imperfections are responsible for the mismatch between theoretical and experimental results. The effect of shell thickness, radius and length variation on buckling load and buckling mode has also been studied. Copyright © 2009 John Wiley & Sons, Ltd.

Pipelines are one of the most important elements of offshore oil and gas production system. Subsea pipelines can be instable so mattresses are put on them to avoid this problem. These mattresses are made of concrete and their interaction... more

Pipelines are one of the most important elements of offshore oil and gas production system. Subsea pipelines can be instable so mattresses are put on them to avoid this problem. These mattresses are made of concrete and their interaction with the pipeline is studied in this dissertation
A pipe section is designed using DNV rules and a Finite Element Model is created in ANSYS to analyze the effect of the mattress’ load on the pipe. Different responses are extract from the Finite Element
Analysis, in particular the frequency response and the mechanical behavior of pipes with different mattresses lengths and loads. Also, the ovalization of the pipe is evaluated.
The study concludes that the mattress load do not change the eigenvalue buckling of the pipeline structure. However, there is around 0.2% ovalization due to the effect of the mattress. This value should
be added to other uncertainties in the design process to reduce the risk of pipeline failure. For the designed pipe this ovalization corresponds to 3% reduction in the collapse pressure of the pipe.
Moreover, the location of maximum ovalization is defined around nine meters from the mattress edge and therefore this location should be the focus in inspection operations.

UPHEAVAL BUCKLING OF OFFSHORE pipelines occurs as a result of axial compression induced along the pipelines due to large temperature differences and high internal pressures. This paper aims to research the causes of upheaval buckling,... more

UPHEAVAL BUCKLING OF OFFSHORE pipelines occurs as a result of axial compression induced along the pipelines due to large temperature differences and high internal pressures. This paper aims to research the causes of upheaval buckling, give an overview of the analytical methods, and develops an Excel spreadsheet for initial assessment. Several models of upheaval buckling have been identified and discussed, such as those based on idealized or perfect pipelines, which are related to the railway track analysis and those based on imperfections. The buckle temperatures of the perfect pipelines are proportional to the buckle lengths and axial forces. With the consideration of imperfections, buckle temperatures become inversely proportional to the imperfection heights, therefore larger imperfections would require smaller temperatures to propagate upheaval buckling. Increasing the downward load on the pipelines aids the prevention of upheaval buckling. Also, relevant methods to mitigate against the occurrence of upheaval buckling have been discussed. The use of finite-element analysis which considers the seabed profile and plastic deformation of pipe wall would be suitable for precise analysis

An arch is a curved structure in its elevation, loaded in-plane having supports are prevented from stretching out, and loads are supported mainly in compression. Arches are extensively used in infrastructure projects to provide large span... more

An arch is a curved structure in its elevation, loaded in-plane having supports are prevented from stretching out, and loads are supported mainly in compression. Arches are extensively used in infrastructure projects to provide large span structures, especially in bridges owing to its effective load carrying mechanism. For the case study, a 60m clear span standard bowstring is analyzed. The study has been done for comparison of buckling factor given in Eurocode 3: part 2 with the model analyzed.

Container crane tipe RTG merupakan jenis pesawat angkat yang digunakan dalam intensitas kerja tinggi dengan karakteristik pembebanan berulang atau bersifat siklis, diterapkan dalam frekuensi tinggi dalam waktu yang relatif panjang.... more

Bu çalışmada "ASME Section VIII Division 1, 2001 Edition" a göre, belirli deprem yükleri altında tasarlanmış ince cidarlı silindirik kolon türü basınçlı kapların, yeni çalışma şartları ve artan deprem yüklerine göre doğrusal olmayan... more

Bu çalışmada "ASME Section VIII Division 1, 2001 Edition" a göre, belirli deprem yükleri altında tasarlanmış ince cidarlı silindirik kolon türü basınçlı kapların, yeni çalışma şartları ve artan deprem yüklerine göre doğrusal olmayan statik gerilme analizi, özdeğer (eigenvalue) yöntemi ile burkulma analizi, cevap spektrum yüklemesi kullanılarak mod birleştirme yöntemi ile dinamik analiz uygulanması sonucunda en uygun takviyelendirme yönteminin seçilmesi amaçlanmış ve bu yöntem kullanılarak gerçek bir basınçlı kolonun takviyelendirilmesi anlatılmıştır.

Steel columns in sway and nonsway frames that are spliced along their length generally have a lower strength capacity in compression. This load capacity can be further reduced owing to the inevitable presence of small geometrical... more

Steel columns in sway and nonsway frames that are spliced along their length generally have a lower strength capacity in compression. This load capacity can be further reduced owing to the inevitable presence of small geometrical imperfections in the form of the out-of-straightness of the column and column segment misalignment. The current work examines the buckling behavior of a framed spliced column with initial imperfections and the possibility of a nonuniform cross section. A geometrically nonlinear model accounting for imperfect elastic buckling behavior is formulated using the differential equations of equilibrium. This is followed by a study of the imperfection sensitivity to the linearly evaluated critical load. A discussion on the variation of the load-carrying capacity with the level of imperfections on a practical spliced column is also presented. The findings suggest that a spliced column can be considered equivalent to a prismatic Euler column, with an appropriate effective length, for design purposes. In this context, some implications for design are deduced from the presented analysis.