Loading...
Search for:
nonlinear-analysis
0.016 seconds
Total 192 records
The Effect of Arrangement of Viscoelastic Dampers in the Performance of Steel Structures Using Incremental Dynamic Analysis
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Including control systems structures against lateral forces such as dynamic loads, earthquakes etc. are viscoelastic damper, that their use in recent years on the structure had positive results. Although the use of dampers improve certain behavioral characteristics, such as relative displacement, but can increase the structural acceleration and energy absorption structures. Passive damper performance depends on several factors such as temperature, time, frequency, stiffness of bracing and structures, type of loading that should any of these uncertain in the optimal design of controlled structures taken into account. Common method of achieve proper placement pattern of passive dampers, which...
Analytical and Parametric Study of Telescopic Lead Shear Damper
, M.Sc. Thesis Sharif University of Technology ; Eskandari, Morteza (Supervisor) ; Arghavani, Jamal (Supervisor)
Abstract
This research studies behavior and implementing of telescopic lead shear damper in structures. Telescopic lead shear damper (TLSD) is a type of metallic yielding dampers that can dissipated energy with usage of shear yielding of lead. TLSD is made from behind act of two lead shear damper (LSD) like a telescope. Lead shear damper composed of two coaxial steel pipes where their interfacial gap is filled with pure lead. The interface of lead and steel pipes are roughened in a threaded form to guarantee the no-slip condition across the interface. Due to stable and fat force displacement hysteresis loops of TLSD, this device can be used in structures subjected to wind, seismic, and other dynamic...
Nonlinear Analysis of Structures with Concrete Filled Steel Tubular Columns
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In recent years using concrete and steel together in buildings and bridges to mix their advantages and compensate disadvantages is very common especially in seismic zones. Using Concrete Filled Steel Tubular (CFST) columns is one of these methods. In these columns, steel tube has longitudinal and lateral reinforcement role for helping concrete core to resist against bending moment, shear and tension. Steel tube also creates confinement in concrete and increase compressive strength and prevents concrete from spalling. Concrete core increases stiffness of column and reduces capability of inward local buckling. Behaviors of CFST columns are influenced by loading, characteristics of materials...
Influence of Floor Diaphragm on Seismic Response of RC Structures
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Modeling is one of the most important steps in analysis and design of structures. Most of the time behavior of floor diaphragms is assumed completely rigid in their plane in order to simplicity in practical design. Although this assumption leads to acceptable results in analysis and design of conventional buildings, erroneous results may assess in some particular buildings—for instance narrow buildings with stiff end walls. Accordingly, behavior of these buildings in future earthquakes opposes those were predicted in design phase, and they are so vulnerable since in-plane deflection of floor diaphragms are striking which cannot be ignored. This thesis investigates the significance of...
An Investigation of the Effects of Zipper Strut on the Cost and Energy Dissipation Capacity of Concentrically & Eccentrically Chevron Braced Systems
, M.Sc. Thesis Sharif University of Technology ; Ahmadizadeh, Mehdi (Supervisor)
Abstract
Concentric and eccentric chevron braces are among the more economical lateral force resisting systems for structures. However, chevron braced systems are prone to concentration of damage in a single story and formation of soft stories when buckling occurs in the bracing elements. This leads to a gradual loss in the structural performance, particularly as the height of the structure increases. One of the most notable methods to alleviate this problem and improve the structural performance is the addition of zipper struts to concentrically chevron braced frames that are known to improve the distribution of plastic energy dissipation along the height of the structure. While this usually...
A Study of Steel Frames with Steel Plate Shear Wall Resisting System Subjected to Blast Loading
, M.Sc. Thesis Sharif University of Technology ; Aligani Moghaddam, Hassan (Supervisor) ; Saedi Darian, Amir (Co-Supervisor)
Abstract
Over the last years, terrorist attacks and accidental explosions have brought on a need for research in the field of structural engineering to study the response of a building subjected to blast loading conditions. An explosion within or surrounding a building, not only can have disastrous effects causing both structural damage or failure, but may also lead to the death of human beings.In order to prevent these catastrophes and gain a better understanding of responses of the buildings and lateral resisting systems with different characteristics, the study of the behavior of the lateral resisting systems under blast loading conditions is essential. This research will also aid in the...
Heart Arrhythmia Classification based on Nonlinear Analysis and Dynamic Behavior of Heart Rate Variability (HRV)Signal
, M.Sc. Thesis Sharif University of Technology ; Bagheri Shouraki, Saeed (Supervisor) ; Ghorshi, Mohammad Ali (Co-Advisor)
Abstract
Detection and classification of arrhythmia is important especially for patients in Emergency care units. Early diagnosis of cardiac arrhythmia makes it possible to choose appropriate anti arrhythmic drugs, and is thus very important for improving arrhythmia therapy. Computer-Assisted Diagnostic (CAD) Systems are used in recent decades in which extracted features and classifiers are the most important factor. In this project, we try to focus on both of these two major factors in heart arrhythmia classification using HRV signal. Therefore, in this project, we try to classify different groups of arrhythmia using HRV signal processing especially the nonlinear processing. Our main aim is to...
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vahid (Supervisor)
Abstract
In this thesis, change of the behavior of frames due to adding damping devices to frames is taken into consideration and a non-linear static analysis computer program is developed . In numerical studies a few one and two story frames are used. The results of previous studies have shown that, adding energy damping devices to the structural systems, results in structure damping increase, story drift and base shear decrease. To reveal the behavior of the new bracing system, experimental and numerical studies are made. The main point in design of this bracing system, was the capability of easy replacement and maximum damping with minimum damage. It must be declared that design thought of this...
Nonlinear Seismic Interaction Behavior of Concrete Shear wall-Frame with Different Stiffness Ratio of Wall and Frame
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
Wall-Frame interaction under lateral load has been considered in studies, and it is concluded that interaction lateral forces of rigid frame and shear wall varies at different stories. This is resulted from of different mode shape of rigid frame and shear wall under lateral loads which are shear and bending mode, respectively. However most codes recommend a minimum strength for frame, equal to 25% of total lateral force, as an acceptance criterion of shear wall-frame dual action; otherwise this minimum strength does not fully comply with horizontal distribution of lateral load according to relative stiffness of components.The purpose of this article is to study nonlinear seismic response of...
Application of endurance time method in nonlinear seismic analysis of steel frames
, Article Procedia Engineering ; Volume 14 , 2011 , Pages 3237-3244 ; 18777058 (ISSN) ; Estekanchi, H. E ; Seyedain Boroujeni, S ; Sharif University of Technology
2011
Abstract
In Endurance Time (ET) method gradually intensifying acceleration functions are created in a manner that the linear and nonlinear response spectra of them, while being proportional to average of real earthquakes spectra, intensifies in a uniform manner with time. These functions are used as input functions for nonlinear time history analysis of structures and performance of structures is assessed based on the maximum time duration that they can meet the specified performance objectives. In this paper, application of the ET method in nonlinear seismic analysis of structures has been investigated. Numerical procedures and optimization techniques that are used for the production of acceleration...
Nonlinear analysis of chatter in turning process using dimensionless groups
, Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 37, Issue 4 , July , 2015 , Pages 1151-1162 ; 16785878 (ISSN) ; Jalili, M. M ; Movahhedy, M. R ; Sharif University of Technology
Springer Verlag
2015
Abstract
A new 3-D nonlinear model of chatter vibration in turning process is presented in this paper. The workpiece is modeled as a rotating clamped-free beam which is excited by cutting forces. π-Buckingham theory is used to extract dimensionless parameters for this problem. Using these parameters, non-dimensional equations of motion are developed. An approximate analytical solution of the nonlinear problem is obtained. A study of the influence of different parameters on the stability results is developed. Using these results, turning velocity intervals for stable and unstable cuts are determined
Blind source separation in nonlinear mixture for colored sources using signal derivatives
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 25 August 2015 through 28 August 2015 ; Volume 9237 , August , 2015 , Pages 193-200 ; 03029743 (ISSN) ; 9783319224817 (ISBN) ; Babaie Zadeh, M ; Jutten, C ; Sharif University of Technology
Springer Verlag
2015
Abstract
While Blind Source Separation (BSS) for linear mixtures has been well studied, the problem for nonlinear mixtures is still thought not to have a general solution. Each of the techniques proposed for solving BSS in nonlinear mixtures works mainly on specific models and cannot be generalized for many other realistic applications. Our approach in this paper is quite different and targets the general form of the problem. In this advance, we transform the nonlinear problem to a time-variant linear mixtures of the source derivatives. The proposed algorithm is based on separating the derivatives of the sources by a modified novel technique that has been developed and specialized for the problem,...
Solution of nonlinear fractional differential equations using homotopy analysis method
, Article Applied Mathematical Modelling ; Volume 34, Issue 6 , 2010 , Pages 1634-1641 ; 0307904X (ISSN) ; Sharif University of Technology
2010
Abstract
In this article, the homotopy analysis method has been applied to solve nonlinear differential equations of fractional order. The validity of this method has successfully been accomplished by applying it to find the solution of two nonlinear fractional equations. The results obtained by homotopy analysis method have been compared with those exact solutions. The results show that the solution of homotopy analysis method is good agreement with the exact solution. Crown
A semilinear PDE with free boundary
, Article Nonlinear Analysis, Theory, Methods and Applications ; Volume 151 , 2017 , Pages 145-163 ; 0362546X (ISSN) ; Shahgholian, H ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
We study the semilinear problem Δu=λ+(x)(u+)q−1−λ−(x)(u−)q−1inB1, from a regularity point of view for solutions and the free boundary ∂{±u>0}. Here B1 is the unit ball, 1
Solution of coupled system of nonlinear differential equations using homotopy analysis method
, Article Nonlinear Dynamics ; Volume 56, Issue 1-2 , 2009 , Pages 159-167 ; 0924090X (ISSN) ; Ganjiani, H ; Sharif University of Technology
2009
Abstract
In this article, the homotopy analysis method has been applied to solve a coupled nonlinear diffusion-reaction equations. The validity of this method has been successful by applying it for these nonlinear equations. The results obtained by this method have a good agreement with one obtained by other methods. This work illustrates the validity of the homotopy analysis method for the nonlinear differential equations. The basic ideas of this approach can be widely employed to solve other strongly nonlinear problems. © 2008 Springer Science+Business Media B.V
Non-linear thermo-mechanical cylindrical bending of functionally graded plates
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 222, Issue 3 , 2008 , Pages 305-318 ; 09544062 (ISSN) ; Nosier, A ; Sharif University of Technology
2008
Abstract
Based on the first-order non-linear von Karman theory, cylindrical bending of functionally graded (FG) plates subjected to mechanical, thermal, and combined thermo-mechanical loadings are investigated. Analytical solutions are obtained for an FG plate with various clamped and simply-supported boundary conditions. The closed form solutions obtained are very simple to be used in design purposes. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The effects of non-linearity, material property, and boundary conditions on various response quantities are studied and...
Estimating structural damage of steel moment frames by Endurance Time method
, Article Journal of Constructional Steel Research ; Volume 64, Issue 2 , 2008 , Pages 145-155 ; 0143974X (ISSN) ; Arjomandi, K ; Vafai, A ; Sharif University of Technology
2008
Abstract
In Endurance Time (ET) method, structures are subjected to gradually intensifying accelerograms and their performance is judged based on the maximum time duration in which they can satisfy the predefined endurance criteria. Damage indexes are used in ET method as the endurance criteria. In this paper, correlation between the values of various damage indexes as obtained from nonlinear time-history analysis of steel moment frames subjected to scaled earthquakes are compared with those from ET method at the same level of spectral acceleration. It is shown that the average value of various damage indexes can be estimated from ET analysis results. Advantages, accuracy and limitations of this...
Nonlinear analysis of structures using new one dimensional elements under periodic loading
, Article 9th International Conference on Computational Plasticity: Fundamentals and Applications, COMPLAS IX, Barcelona, 5 September 2007 through 7 September 2007 ; Issue PART 2 , 2007 , Pages 956-959 ; 9788496736290 (ISBN) ; Farrokhpour, L ; Jahromi, M. Y ; Broumand, P ; Ahmadi, M. M ; Sharif University of Technology
2007
Abstract
In this study a new method of nonlinear dynamic analysis of structures is described. New one dimensional higher order elements have been used to more accurately model the behavior of the structure through computations on frame sections. In addition, more effects of periodic loading are accounted for in the element's powerful hysteretic loop model. © CIMNE, 2007
Voice conversion using nonlinear principal component analysis
, Article 2007 IEEE Symposium on Computational Intelligence in Image and Signal Processing, CIISP 2007, Honolulu, HI, 1 April 2007 through 5 April 2007 ; 2007 , Pages 336-339 ; 1424407079 (ISBN); 9781424407071 (ISBN) ; Seyed salehi, S. A ; Sadati, N ; Noori Hosseini, M ; Sharif University of Technology
2007
Abstract
In the last decades, much attention has been paid to the design of multi-speaker voice conversion. In this work, a new method for voice conversion (VC) using nonlinear principal component analysis (NLPCA) is presented. The principal components are extracted and transformed by a feed-forward neural network which is trained by combination of Genetic Algorithm (GA) and Back-Propagation (BP). Common pre- and post-processing approaches are applied to increase the quality of the synthesized speech. The results indicate that the proposed method can be considered as a step towards multi-speaker Voice conversion. © 2007 IEEE
Static and dynamic pushover analysis of steel moment resisting frames
, Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 3 , 2006 , Pages 459-464 ; 9748257231 (ISBN); 9789748257235 (ISBN) ; Rahimzadeh Rofooei, F ; Khajeh Ahmad Attari, N ; Shodja, A. H ; Sharif University of Technology
2006
Abstract
Pushover analysis is a simplified nonlinear analysis technique that can be used to estimate the dynamic demands imposed on a structure under earthquake excitations. One of the first steps taken in this approximate solution is to assess the maximum roof displacement, known as target displacement, using the base shear versus roof displacement diagram. That could be done by the socalled dynamic pushover analysis, i.e. a dynamic time history analysis of an equivalent single degree of freedom model of the original system, as well as other available approximate static methods. In this paper, a number of load patterns, including a new approach, are considered to construct the related pushover...