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rahimzadeh-rofooei--fayyaze
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Undamaged-to-Damaged Structural Response Mapping for Structural Health Monitoring Using Generative A dversarial Networks (GANs)
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaze (Supervisor)
Abstract
In this study, a Cycle-Generative Adversarial Network (Cycle-GAN)-based approach is proposed to transform the dynamic response of structures from a healthy to a damaged state and vice versa, aiming to improve damage identification and reduce the need for paired data. This method enhances signal conversion accuracy, facilitating the prediction of damage presence or absence while minimizing dependency on extensive experimental data. Traditional Structural Health Monitoring (SHM) methods, such as mechanical sensors and numerical analyses, face limitations such as high costs, operator dependency, and the requirement for fully paired data. Deep learning algorithms, particularly those based on...
Improving the seismic torsional behavior of plan-asymmetric, single-storey, concrete moment resisting buildings with fluid viscous dampers
, Article Earthquake Engineering and Engineering Vibration ; Volume 15, Issue 1 , 2016 , Pages 61-78 ; 16713664 (ISSN) ; Mohammadzadeh, S ; Sharif University of Technology
Institute of Engineering Mechanics (IEM)
2016
Abstract
The optimal distribution of fluid viscous dampers (FVD) in controlling the seismic response of eccentric, single-storey, moment resisting concrete structures is investigated using the previously defined center of damping constant (CDC). For this purpose, a number of structural models with different one-way stiffness and strength eccentricities are considered. Extensive nonlinear time history analyses are carried out for various arrangements of FVDs. It is shown that the arrangement of FVDs for controlling the torsional behavior due to asymmetry in the concrete structures is very dependent on the intensity of the peak ground acceleration (PGA) and the extent of the structural stiffness and...
Application of active piezoelectric patches in controlling the dynamic response of a thin rectangular plate under a moving mass
, Article International Journal of Solids and Structures ; Volume 46, Issue 11-12 , 2009 , Pages 2429-2443 ; 00207683 (ISSN) ; Nikkhoo, A ; Sharif University of Technology
2009
Abstract
The governing differential equation of motion for an undamped thin rectangular plate with a number of bonded piezoelectric patches on its surface and arbitrary boundary conditions is derived using Hamilton's principle. A moving mass traveling on an arbitrary trajectory acts as an external excitation for the system. The effect of the moving mass inertia is considered using all the out-of-plane translational acceleration components. The method of eigenfunction expansion is used to transform the equation of motion into a number of coupled ordinary differential equations. A classical closed-loop optimal control algorithm is employed to suppress the dynamic response of the system, determining the...
Dynamic-based pushover analysis for one-way plan-asymmetric buildings
, Article Engineering Structures ; Volume 163 , 2018 , Pages 332-346 ; 01410296 (ISSN) ; Mirjalili, M. R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
A simple Dynamic-based Pushover analysis for Plan Asymmetric buildings (DPPA) is proposed with the aim of properly considering the effects of torsional behavior as well as the higher modes in the applied lateral load pattern. According to the proposed method, the peak story drifts obtained from the response spectrum analysis (RSA) can be resolved into their translational and rotational components, and the related equivalent static lateral forces and torsional moments can be calculated. Consequently, for accurate estimation of the maximum drift demands of plan-asymmetric buildings, it is proposed that the drift responses obtained from the RSA for the stiff and flexible edges of the building...
Evaluating the Seismic Performance Factors of Diagrid Structures and Improving their Behavior using Buckling Restrained Braces
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
In this study, seismic performance of steel diagrid structures is investigated using far-field earthquake records and their seismic performance factors, such as overstrength factor (Ω_0), ductility ratio (µ_T) and response modification coefficient (R) are evaluated according to the FEMA P695. To meet this objective, 12 archetype 3-D models of diagrid structure with two different height of 8 and 12 stories and three different diagonal angles of 45, 63.4 and 71.5 degrees are designed according to the ASCE 7-10 and using response modification factor R=3.6. With regard to the main horizontal beam connections with the diagrid system, equal number of models with pin and rigid type of connections...
Determination of the Equivalent Linear Systems of Nonlinear MDOF Steel Moment Resisting Frames
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
The purposeof this study isto findthe propertiesof an equivalent linear Multiple Degrees of Freedom (MDOF) system, or so-called substitute structure, that its response is an approximation ofthe target actualnonlinearMDOF structure’s response (Shodja, 2013). In that regard,thestiffness anddampingmatricesofthe substitutestructure are considered as functions ofthe stiffnessand dampingmatrices ofthe actualnonlinear structure. Inthisway,the substitute structurescan be constructedthroughtrial and errorfor structures with different fundamentalperiods, damping ratios and number of floors.Inthat regard, a number of multi-story steel moment resisting frames are considered. The ductilities of these...
Dynamic response of geometrically nonlinear, elastic rectangular plates under a moving mass loading by inclusion of all inertial components
, Article Journal of Sound and Vibration ; Volume 394 , 2017 , Pages 497-514 ; 0022460X (ISSN) ; Enshaeian, A ; Nikkhoo, A ; Sharif University of Technology
Academic Press
2017
Abstract
Dynamic deformations of beams and plates under moving objects have extensively been studied in the past. In this work, the dynamic response of geometrically nonlinear rectangular elastic plates subjected to moving mass loading is numerically investigated. A rectangular von Karman plate with various boundary conditions is modeled using specifically developed geometrically nonlinear plate elements. In the available finite element (FE) codes the only way to distinguish between moving masses from moving loads is to model the moving mass as a separate entity. However, these procedures still do not guarantee the inclusion of all inertial effects associated with the moving mass. In a prepared...
The seismic performance of K-braced cold-formed steel shear panels with improved connections
, Article Journal of Constructional Steel Research ; Volume 135 , 2017 , Pages 56-68 ; 0143974X (ISSN) ; Farahbod, F ; Rahimzadeh Rofooei, F ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this paper the performance of light weight K-braced cold formed steel (CFS) shear panels under cyclic loading is experimentally evaluated. It is generally known that the brace-stud connection details has an important effect on the performance of the braced CFS shear panels in terms of lateral stiffness, energy dissipation, and ductility factor. In this study, four full-scale, 2.4 m × 2.4 m, braced CFS shear panels made of C-sections were tested. It was observed that proper modification of the currently utilized braced to stud connections in K-braced, CFS shear panels could enhance their performance considerably by increasing their ultimate shear resistance up to 7 folds. Furthermore,...
Damage detection in existing reinforced concrete building using forced vibration test based on mode shape data
, Article Journal of Civil Structural Health Monitoring ; Volume 7, Issue 1 , 2017 , Pages 123-135 ; 21905452 (ISSN) ; Niousha, A ; Rahimzadeh Rofooei, F ; Sharif University of Technology
Springer Verlag
2017
Abstract
Damage detection of a full-scale nine-story reinforced concrete building is investigated using forced vibration test (FVT). The building was the former Civil and Architecture Department of Tohoku University located in Sendai Japan. Earthquake resistance elements of this building were severely damaged in 1978 Miyagi-Ken Oki earthquake and the building was retrofitted on 2001. FVT was performed on the structure before and after retrofitting with same sensor arrangement. Using data acquired from sensors, system identification was performed using rational fraction polynomial and the damage assessment (detection and location) was done by modal assurance criterion and its derivatives. The results...
Evaluation of the Change in Friction Dampers’ Optimal Slip Load in 3-D StructuralModels Due to Soil-Structure Interaction
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
In this study, the change in friction damper’s optimal slip load in 3-D structures due to soil-structure interaction was evaluated. Using AISC-LRFD code, an 8 story shear building has been designed considering gravitational and equivalent static lateral loads. Then, the changes in friction damper’s optimal slip load due to PGA and soil type variation were studied. In this part two PGAs and two soil types were considered. Seven strong ground motions, recorded on soil types E and D was used for each of the two soil types. After normalizing the PGAs of selected records, these records were used for dynamic time history analyses. In the next step, the soil-structure interaction effect has been...
Evaluation of the Performance of Viscoelastic Dampers in Controlling the Seismic Induced Response of Structures
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
In the present study, the performance of Viscoelastic Dampers in reducing the seismic response of the structures was investigated. For this purpose, first the effect of added damping to the system was studied. Number of 3-D steel structural models, with and without eccentricity which are designed with the 2800 code (first edition) and 519 code provisions that is not satisfied the provisions of the code-2800(third edition) is considered. It is assume that this system is located on a relatively stiff soil (soil type II based on Iranian Seismic Standard Code - 2800), a number of compatible earthquake records also considered to be used in the parametric studies. The results indicate that in...
3-D Seismic Evaluation of on Grade Cylindrical Flexible Storage Tanks Considering Soil-Structure Interaction
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
The circular flexible cylindrical liquid tanks usually are made of steel or aluminum and in majority of cases are built on grade due to its economic advantages. The most important part of a safe design of a storage tanks is the accurate estimation of the seismically induced lateral forces that should be transferred to its base through the tank shell and its support. Seismic behavior of liquid storage tanks is quite different from regular buildings and industrial structures due to its nonlinear behavior caused by complex distribution of hydrodynamic pressure, buckling of its walls, etc.. Moreover, the effect of rocking motion caused by the under laying soft soil, on its response parameters...
Evaluation of the Performance of Passive TMDs in Damage Reduction of 2-D Concrete Structures
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
The detuning of the structures equipped with Tuned Mass Dampers (TMDs) caused by their nonlinear behavior under strong ground motions is a real concern in their practical application. This thesis presents a feasibility study on the effectiveness of TMDs in reducing the seismic response and the resulting structural damage of reinforced concrete structures under intense ground motion. A number of 2-D concrete moment resisting frames with different numbers of stories are considered. TMDs are used as a mean to protect these structural models against ground excitation. The mass of TMDs are varied from 1% to 5% of the first effective modal mass of the structural models. IDARC 2-D program is used...
On the Base Shear Force Distribution Along the Height of Base-Isolated Structures With LRB Isolators Subjected to Near Field Earthquakes
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
In recent years there has been a huge amount of attention in the application of the base isolation system as a passive procedure to limit seismic response of structures. A number of international codes including UBC97, ASCE07-2005, and ASCE-2010 have devoted a special part for the Seismic analysis and design of base-isolated structures. The present work investigates the vertical distribution of the lateral seismic force, for base-isolated structures suggested by the ASCE07_05 code under near field earthquakes. Near field earthquakes have attracted so much interest among the researchers and engineers due to their disastrous effects on structures. According to the recorded data, it is...
Investigation of the Damage Imposed on Steel Structures under Near Field Earthquakes from a Performance Based Design Viewpoint
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
The considerable structural damage caused by near field earthquakes has revealed the need for further research on their characteristics and their corresponding effects on structures. The short-duration, high- energy pulses present in these types of earthquakes impose high demands on the structures compared to far field ground motions. Thus, more research is needed to improve the current design methods, especially from a performance based point of view for the structures close to faults. This study is about damage assessment of steel moment resisting frame structures under near-field ground motions from a performance based design point of view. A number of 3 and 9-story, 3-D structural model...
Performance Evaluation of Piezoelectric Based Control System to Mitigate the Vibration of Bridges Caused by Traffic Loads and Seismic Excitation
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
A large number of bridges in Iran are deteriorating under long and heavy traffic loadings, while getting closer to the end of their design life time. Therefore, many of them have been exhibiting various problems such as excessive vibration or large deflection under the normal service loadings. So, mitigating traffic-induced bridge vibration and damages is necessary to extend their efficient period of serviceability. On the other hand, application of active and passive control devices in structural retrofitting have absorbed the attention of many engineers and researchers. In this work, the performance of an active control system made of piezoelectric actuators is investigated in reducing the...
Investigating the Location of Damping Center to Reduce the Torsional Response of Asymmetric Concrete Structures Under Near-Field Earthquakes
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Researches carried out on the damages imparted to the building structures under severe earthquakes have shown the importance of asymmetry effects of the buildings on the level of these damages. In these cases, the structures enter into the nonlinear state of their behavior and the structural elements, as well as nonstructural ones undergo large deformations. Additional damping systems have been proposed in many studies to avoid enforcing such large forces on the structures. One example of these systems is viscous fluid damper. The effectiveness of this type of dampers in reduction of the forces has been shown in many previous works. In this research we look for a damping eccentricity which...
Probabilistic Estimation of Maximum Inelastic Displacement Demands for Performance-Based Design Considering Soil-Structure Interaction
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
In the current design Codes, the estimation of maximum inelastic Single Degree Of Freedom (SDOF) displacements is done through simplified procedures by either applying modification factors on maximum SDOF elastic displacement demands or by considering equivalent SDOF systems with elongated fundamental period and increased damping ratio. Thus, the inherent uncertainty caused by approximating maximum inelastic displacements with maximum elastic displacements is neglected. On the other hand, in time history dynamic analysis of structures, the free field recorded ground motions are applied to the base of structures. Obviously, this procedure would be correct when the structure is built on firm...
Proposing Appropriate Lateral Load Pattern for 3-D Pushover Analysis of Unsymmetric-Plan Building Structures
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
Abstract
Recent studies in the area of damage assessment of structures under severe earthquakes have shown that plan asymmetry of structures have considerable effects on the severity of the induced damages. In these cases, structure enters into its nonlinear behaviour, and both structural and nonstructural elements sustain large forces and deformations. Nowadays, due to the complication of nonlinear dynamic analyses in estimating these forces and deformations in case of seismic ground motion, the use of nonlinear static analysis methods has increased. These procedures expose the structures to monotonically increasing lateral forces with an invariant height-wise distribution until a predetermined...
Numerical Analysis of Buried Pipelines Strengthened by FRP Subjected to Reverse Faulting
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofooei, Fayaz (Supervisor)
Abstract
Buried pipes are among the most important urban infra-structures which are developed to distribute water, gas, oil, etc.. Researchers have already demonstrated that extreme failures which lead to total disruption of the pipelines, both mains and the distribution network, due to permanent ground displacement in fault zones. In order to avoid any disturbance in the regular performance of pipelines and prevention of environmental contamination, there is a need to investigate the vulnerability of pipelines and their seismic retrofitting, if necessary. In the presented study, the method of pipeline retrofitting by high strength CFRP composite is investigated. In that regard, using a 3D model of...