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Parametric study and computation of seismic performance factors of braced shear panels
, Article Scientia Iranica ; Volume 23, Issue 2 , 2016 , Pages 460-474 ; 10263098 (ISSN) ; Mofid, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
By locating a steel shear panel on the intersection point of the X-braces, concentrically or eccentrically braced shear panel (CBFSP or EBFSP) is formed. In this paper, to perform parametric study, 1-story CBFSP and EBFSP models with span length greater or less than height are considered. Using linear static analyses, the effects of size and location of the shear panel on the lateral stiffness of the frame with respect to the moment resisting frame with the same member sections are investigated. Next, for 1- And 3-story models, maximum displacement, along with base shear, and the ratio between the dissipated energy and input energy are examined under 4 ground motion records. Behavior of the...
In-plane vibration analysis of horizontally curved beams resting on visco-elastic foundation subjected to a moving mass
, Article Mechanical Systems and Signal Processing ; Volume 172 , 2022 ; 08883270 (ISSN) ; Abdoos, H ; Khaloo, A. R ; Mofid, M ; Sharif University of Technology
Academic Press
2022
Abstract
This paper deals with the in-plane dynamics of Horizontally Curved Beams (HCBs) supported by a visco-elastic foundation under the excitation induced by a moving mass. What has been included as worthy of detailed exposition is the inevitable contribution of the inertial actions of the mass object into the problem formulation. By taking into account the effect of Coriolis acceleration, centrifugal force and rotary inertia, the governing coupled non-linear differential equations of equilibrium for a simply supported HCB are derived. In the proposed solution, a new system of linear ordinary differential equations is distilled from the governing differential equations of motion, which can be...
Investigating the Dynamic Amplification Factor for Pancake Progressive Collapse
, M.Sc. Thesis Sharif University of Technology ; Rahimzadeh Rofouei, Fayyaz (Supervisor)
Abstract
Progressive collapse occurs when the loading path of a structure is changed so that the other structural elements loaded beyond their capacity and fail. Generally, structural progressive collapse is categorized in different types based on the failure progress mechanism. Most dramatic progressive collapse occurred in 1968 at the Ronan Point residential apartment through an internal gas explosion. The type of progressive collapse of the aforementioned building was the Pancake collapse. Widespread efforts have been put to introduce a simplified static procedure to simulate the removal column phenomenon as in the Pancake collapse, which is a dynamic event involving vibration of building...
A Self-Consistence Numerical Method to Estimate Effective Mechanical Properties of Fibrous Composites
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkhaili, Ali (Supervisor)
Abstract
One of the most widely used methods in the study of the mechanical behavior of fiber-reinforced polymers is modeling and simulation of a unit cell behavior. According to the arrangement of composite materials, the unit cell is selected in order to include and represent actual constructions of the material. In this study a numerical self-consistence method is proposed to estimate effective properties of Carbon-epoxy composite materials. In this method, in addition of two main phases i.e. matrix and fiber, a phase of composite properties is also considered surrounding the unit cell. First using analytical and semi-empirical methods, the properties are calculated and are converged after...
Wind turbine transformer improved design method entailing resonance blocking
, Article IET Electric Power Applications ; Volume 12, Issue 9 , 2018 , Pages 1337-1343 ; 17518660 (ISSN) ; Vakilian, M ; Lehtonen, M ; Sharif University of Technology
Institution of Engineering and Technology
2018
Abstract
A wind turbine transformer resonance can occur due to high frequency transients at its terminal i.e.; under its energization through a length of cable. Occurrence of resonance can be addressed by a sophisticated transformer design procedure. The goal is to obtain an optimum design capable of controlling the frequency response of the winding in such a way to avoid occurrence of any resonance under transient conditions. Three insulation clearances parameters which are employed for the wind turbine transformer winding design have been investigated in design of a (800 kVA, 690/20,000 V) wind turbine transformer to determine effect of their variation on its frequency response. It is shown that...
Deflection amplification factor for estimating seismic lateral deformations of RC frames
, Article Earthquake Engineering and Engineering Vibration ; Volume 14, Issue 2 , 2015 , Pages 373-384 ; 16713664 (ISSN) ; Vatani Oskouei, A ; Rahimzadeh Rofooei, F ; Sharif University of Technology
Institute of Engineering Mechanics (IEM)
2015
Abstract
Different values have been assigned to the ratio of the deflection amplification factor (Cd ) to the response modification factor (R) for a specified force-resisting system in the seismic design provisions while the same application is defined for it. An analytical study of the seismic responses of several reinforced concrete frames subjected to a suite of earthquake records performed in this research indicate that the stories’ overstrength and stiffness distribution along the structural height can affect local deflections more than global ones. Therefore, the Cd /R ratio is calculated based on the ratio of both maximum inelastic to maximum elastic displacements and...
On the out-of-plane dynamic response of horizontally curved beams resting on elastic foundation traversed by a moving mass
, Article Journal of Sound and Vibration ; Volume 479 , 2020 ; Khaloo, A. R ; Foyouzat, M. A ; Sharif University of Technology
Academic Press
2020
Abstract
In this paper, the dynamic behavior of Horizontally Curved Beams (HCBs) resting on an elastic foundation and subjected to a moving mass is investigated. The governing coupled non-linear differential equations of equilibrium are derived, where Coriolis acceleration, centrifugal force and rotary inertia are incorporated in the problem formulation. In the proposed analytical solution, by employing the transition matrix technique, the governing differential equations of motion are subsequently transformed into a new system of linear ordinary differential equations which can be solved using standard numerical procedures. The accuracy as well as the robustness of the solution is ascertained...
Investigation of Moving Oscillator’s Critical Speed on Single-Span Bridge with Roadway Roughness by FEM
, M.Sc. Thesis Sharif University of Technology ; Vafai, Abolhassan (Supervisor) ; Mofid, Masoud (Co-Advisor)
Abstract
In this research the critical speed of a moving oscillator on a single-span bridge with different support (boundary) conditions and by considering the presence of road surface roughness surface with finite element perspective is studied. Due to the fact that passing a moving load on top of the beam causes increased maximum stress and deformations in beam compared to static situation, therefore in reputable codes for bridge design such as AASHTO a dynamic amplification factor is used for designing bridge components. Moving oscillator is a more precise model compared to moving mass for modeling vehicles and the suspension system is modeled as a spring and damper and the moving mass is...
Investigation of Dynamic Behavior of Nonlinear Plates Subjected to a Moving Mass
, Ph.D. Dissertation Sharif University of Technology ; Rahimzadeh Rofooei, Fayyaz (Supervisor) ; Nikkhoo, Ali (Co-Advisor)
Abstract
In this study, effect of a single concentrated moving mass on thin linear and nonlinear rectangular plates is investigated. The present research focuses on the dynamic behavior of thin plates traversed by a moving mass. Although vast amount of literature is available regarding the modeling of plates with geometric and material nonlinearity as well as evaluation of the inertial components of the external moving mass, but actually no one has addressed implementation of dynamic effects of moving mass for a nonlinear plate. Due to scientific significance of inertial effects in most cases, the external dynamic loading is considered as a moving mass. However, moving force loading is also taken...
Investigation of Dynamic Behavior of Beams with Different Supports under Moving Vehicles
, M.Sc. Thesis Sharif University of Technology ; Vafai, Abolhassan (Supervisor) ; Esmaeil Pourestekanchi, Homayun (Co-Advisor)
Abstract
With the transportation progress and appearance of transit industry, necessity of modern vehicles redounded to appearance of heavier trucks with higher speeds, moving on the roads. In addition, with the progress in mechanical engineering and automobile industry, appearance of such trucks is growing increasingly. So, bridges as one of the structures that civil engineers design and construct, nowadays are subjected to higher moving dynamic loads in comparison with the past. As a result, lots of investigation and researches in the universities and institutions all over the world are being conducting on the effects of the vehicle speeds on the dynamic stresses of the bridges. Bridge codes...
Quantification of Seismic Performance Factors in Concentrically Braced Frames (CBFs) Equipped with Off-Center Bracing System (OBS)
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
Off-Center Bracing System is a kind of concentric bracing frame that consists of three members and with y- shape layout can provide a necessary opening in the building . Buildings have a concentric lateral bracing system equipped with Off-Center bracing system in lower floors are considered SCBF. to design these buildings according to regulations , it is needed to have Seismic performance coefficients such as response modification factor (R) , over strength factor (Ω0 ) and deflection amplification factor (Cd) .The purpose of the present investigation is quantifying these parameters and evaluation of accuracy based on the proposed method in FEMA P695.In the mentioned ...
Imidazolium-based ionic liquid derivative/CuII complexes as efficient catalysts of the lucigenin chemiluminescence system and its application to H2 O2 and glucose detection
,
Article
Analytical and Bioanalytical Chemistry
;
Volume 407, Issue 20
,
2015
,
Pages 6127-6136
;
16182642 (ISSN)
; Alijanpour, O
; Chaichi, M. J
; Vafaeezadeh, M
; Hashemi, M. M
;
Sharif University of Technology
Springer Verlag
2015
Abstract
The effects of six synthetic imidazolium-based ionic liquids (ILs) on the CuII-catalyzed chemiluminescence of lucigenin (Luc-CL) in the pH range 6.0-11 were investigated. Preliminary experiments found that the CL emission was strongly enhanced or inhibited in the presence of the ILs. The degree of enhancement or inhibition of the CL intensity in the presence of each IL was related to the molecular structure of the IL, the medium used, and the pH. The maximum enhancement of the CL intensity was observed at pH 9.0 (amplification factor=443). This decrease in the pH at which maximum CL enhancement occurred and the substantial signal amplification of the Luc-CL may be related to a strong...
Seismic microzonation of shiraz city, southwest of iran
, Article Geotechnical Earthquake Engineering and Soil Dynamics IV Congress 2008 - Geotechnical Earthquake Engineering and Soil Dynamics, Sacramento, CA, 18 May 2008 through 22 May 2008 ; Issue 181 , 2008 ; 08950563 (ISSN); 9780784409756 (ISBN) ; Sahraeian, S ; Kavand, A ; Kamrani Moghaddam, B ; Sharif University of Technology
2008
Abstract
This paper aims to study the soil dynamics characteristics of central part of Shiraz city near the monument of Persepolis, southwest of Iran. The parameter investigated is natural period of soil sediment. The technique used to obtain this parameter is microtremor measurements. Microtremor measurements were obtained at 120 stations in the city. The data was recorded for two periods of fifteen minutes. Segmental Cross Spectra were applied to calculate spectra. Nakamura's method (H/V) was used for analyzing the measured data. At each site, natural period values were obtained. Because of low accuracy of amplification factors that achieved by microtremor measurements, this factor is neglected in...
Determining The Response Modification Coefficient for Steel Multi-Tiered Braced Frames
, M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin (Supervisor)
Abstract
In order to design buildings such as industrial structures, which use multi-tiered braced frames as their lateral load resisting system, it is required to know seismic performance factors, including the response modification coefficient (R), the overstrength factor (Ω0), and deflection amplification factor (Cd). The main purpose of this study is to assume initial seismic performance factors and evaluate their accuracy based on Fema-P695 methodology. This methodology provides a reliable basis for determining seismic performance factors of different lateral load resisting systems. In this study 8 archetypes have been chosen and designed with initial factors of 6, 2 and 5 as R, Ω0 and Cd,...
Evaluation of Seismic Performance Factors for a Dual Lateral Force Resisting System with Special Moment Frame and Ordinary Concentrically Braced Frame
, M.Sc. Thesis Sharif University of Technology ; Maleki, Shervin (Supervisor)
Abstract
Regarding available structural codes, for designing of buildings with dual lateral force resisting system which includes special moment frames and ordinary concentrically braced frames, we need to determine seismic performance factors. Seismic performance factors embraces of response modification (R), over strength (Ω0) and displacement amplification (Cd) factors. The goal of this research is to evaluate aforementioned factors using the method presented with FEMA P-695. This method represents a reliable framework to assess the seismic performance factors of various kinds of lateral force resisting systems. In this approach, first, archetypes are designed with assuming certain values for...
Seismic Performance of Reinforced Concrete Structures with Corrugated Steel Plate Shear Walls and Evaluation of Seismic Performance Factors
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
There are two aspects to this research. In the first section, a numerical method is used to analyze the seismic performance of reinforced concrete frames with corrugated and flat steel shear walls as a lateral bearing system. In the second section, the seismic performance factors for reinforced concrete frames with corrugated steel shear walls (response modification factor (R), overstrength factor (Ω_0), and deflection amplification factor (C_d)) for reinforced concrete frame with corrugated steel shear walls have been determined.In the first section of this study, a three-story reinforced concrete frame with a flat steel shear wall with a scale of one to three is validated in finite element...
On the seismic performance of Hat Knee Bracing system in low-rise multistory steel structures
, Article Advances in Structural Engineering ; Volume 18, Issue 3 , 2015 , Pages 325-338 ; 13694332 (ISSN) ; Mofid, M ; Zarrin, M ; Sharif University of Technology
Multi-Science Publishing Co. Ltd
2015
Abstract
In this paper, the behavior and performance of a new type of bracing system called Hat Knee Bracing (HKB) is investigated in low-rise multistory steel structures. This novel form of resistant system, which provides reasonable stiffness in moderate earthquakes, consists of a V shaped knee member connected to mid span of the beam and the brace members. In this research work, the "FEMA P695 evaluation method" is utilized in order to explore the nonlinear behavior of the HKB frame, and quantification of three seismic performance factors: Response Modification Factor, Over-strength Factor, and Deflection Amplification Factor. The seismic response simulation of archetype frames is performed using...
On the quantification of seismic performance factors of Chevron Knee Bracings, in steel structures
, Article Engineering Structures ; Volume 46 , 2013 , Pages 155-164 ; 01410296 (ISSN) ; Mofid, M ; Sharif University of Technology
Abstract
As a matter of fact, it is necessary to have the values of Response Modification Factor R, Over-strength Factor Ω0, and Deflection Amplification Factor Cd in order to design seismic-force-resisting systems according to design and loading codes. This study is intended to evaluate these factors for a structural lateral bracing system called Chevron Knee Bracing (CKB). In this type of bracing, the knee elements assist the system to dissipate energy through the formation of plastic flexural and/or shear hinges within the presented bracing system. The approach utilized in this study is according to FEMA P695 based on low probability of structural collapse and involves nonlinear static and dynamic...
Dynamic analysis of laminated composite plates traversed by a moving mass based on a first-order theory
, Article Composite Structures ; Volume 92, Issue 8 , 2010 , Pages 1865-1876 ; 02638223 (ISSN) ; Asghari, M ; Sharif University of Technology
2010
Abstract
The dynamic response of angle-ply laminated composite plates traversed by a moving mass or a moving force is investigated. For this purpose, a finite element method based on the first-order shear deformation theory is used. Stationary and adaptive mesh techniques have been applied as two different meshing schemes. The adaptive mesh strategy is then used to avoid off-nodal position of moving mass. In this manner, the finite element mesh is continuously adapted to follow and comply with the path of moving mass. A Newmark direct integration method is employed to solve the equations of motion. Parametric study is directed to find out how different parameters like mass of the moving object as...