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Total 103 records

    Numerical Analysis of An Annular Gas Turbine Combustor

    , M.Sc. Thesis Sharif University of Technology Gandomi, Mohammad Hossein (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    The goal of this research is the simulation of the annular combustion chamber of the turbine engine utilized by liquid fuel. The achievement to this goal will lead to create numerical tools for parametric study, analysis and combustion chamber designing.For this reason simple geometry has been considered. This simplicity of geometry causes to facilitate in parametric study and decrease in saving time for modeling and meshing. This combustion chamber is a simplified model of engine CF6. In recent study, the k – ε realizable model has been used for turbulence modeling. For non-adiabatic condition, chemical reaction is dissolved by utilizing probability density function along with laminar... 

    Numerical Modeling of the Dynamic Behavior of Piles and Pile Groups Due to Liquefaction- Induced Lateral Spreading

    , M.Sc. Thesis Sharif University of Technology Pakzad, Amin (Author) ; Haeri, Mohsen (Supervisor)
    Abstract
    The phenomenon of lateral spreading occurs as a consequence of earthquakes induced liquefaction in grounds with mild slopes or ending to an opening. This phenomenon has caused many damages to deep foundations and associated structures. Therefore, it is necessary to study and estimate the forces which may be induced by lateral spreading to these structures. Due to the complex mechanism of the effect of lateral spreading on the piles, various tests have been carried out in the form of shaking table as well as centrifuge tests. According to the results of these tests, the forces applied to the piles are significant and can cause crucial damages to deep foundations. On the other hand, because... 

    Analytical and Parametric Study of Telescopic Lead Shear Damper

    , M.Sc. Thesis Sharif University of Technology Homaei, Hossein (Author) ; 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... 

    Numerical Study and Optimization of Effective Parameters in Freeze Desalination

    , M.Sc. Thesis Sharif University of Technology Hashempour, Masoud (Author) ; Afshin, Hossein (Supervisor)
    Abstract
    Freeze desalination as a water refining method has attracted a lot of attention due to its potential in lowering process energy consumption compared to other methods. This method is based on the fact that the dissolved salt is drained from the saline water during its freezing. The current study conducts a parametric study on freezing saline water in a cylindrical container to investigate the impact of geometric and functional factors affecting the desalination quality. This has been done by examining the aforesaid factors in the form of dimensionless parameters such as thermal Grashof number, solutal Grashof number, and Jacob number. In addition, in order to improve the desalination, a novel... 

    Nonlinear Study on the Behavior of Eccentrically Braced with Vertical Link

    , M.Sc. Thesis Sharif University of Technology Niknemat, Mohsen (Author) ; Mofid, Masoud (Supervisor)
    Abstract
    A new eccentrically braced system is discussed. In this system which Named “eccentrically braced frame with vertical link”, the braces is connected to vertical link, instead of floor beam. The vertical link acts as a ductile energy-dissipating element, allowing the rest of the construction such as floor beams, braces and columns remain in the elastic range. In this paper, a parametric study is performed on sample frames with push-over analysis. In these analysis, the efficacy of the variation of link length, link area and the position of the link beam, is studied. The results showed that, the most important effective parameters in improvement of inelastic behavior of frame is decreasing of... 

    Experimental Evaluation and Parametric Study of Side Plate Steel Connection

    , M.Sc. Thesis Sharif University of Technology Navab Lahijani, Saeid (Author) ; Mohtasham Dolatshahi, Kiarash (Supervisor) ; Mirghaderi, Rasool (Co-Supervisor)
    Abstract
    This study aims to parametric study and model steel joints with side plates. steel joints with continuum plates have been seismically acceptable for years, assuming they are designed to be stronger than beams. After the Northridge earthquake, the belief that the adequacy conditions of flexural frame joints were limited to stiffness and strength factors was challenged for two main reasons. First, at the junction of the beam with the column, high tension is created by the seismic force, and as a result, it buckles and loses its strength before reaching the projected force. The second problem is due to the problem of making such connections that it is difficult to weld. Therefore, the problem... 

    Parametric Study of Telescopic Metallic Yielding Dampers

    , M.Sc. Thesis Sharif University of Technology Misaghi, Mohammad (Author) ; Eskandari, Morteza (Supervisor)
    Abstract
    The parametric study of a new introduced metallic yielding damper called telescopic damper is addressed. The telescopic damper comprises of three concentric steel pipes connected together by lead shear keys. The inner and outer steel pipes are subjected to axial loading which results in the shear yielding of the embedded lead cylinders. The inner steel pipe has a lock which limits its movement to some certain extent and beyond this limit the outer tube activates. Employing ABAQUS software, the behavior of damper under cyclic loading is studied numerically. The finite element model is verified by available results in the literature. The effects of inner and outer steel pipes thickness,... 

    Investigating of the Behavior of the Column Base Plate with Eccentirisity Using FEM

    , M.Sc. Thesis Sharif University of Technology Moeini, Amin (Author) ; Vafaei, Abolhassan (Supervisor) ; Mofid, massoud (Co-Advisor)
    Abstract
    Base plate is one of the crucial elements in steel structures which transfer force from column to foundation and also prevent stress concentration in jointing area between them. For investigating the behavior of base plate under different caseloads such as axial, transverse and earthquake loads, it is necessary to consider all the involved elements including column, base plate, foundation, anchor rods and also interaction between these elements. In this study the connection between column and base plate, base plate and foundation are analyzed thoroughly. The behavior of base plate with a box type column with and without stiffener under the static loads is analyzed using finite element... 

    Modeling of in Plane Behavior of Retrofitted Adobe Walls with Finite Element Method under Cyclic Loading

    , M.Sc. Thesis Sharif University of Technology Mohammad Panah, Hossein (Author) ; Bakhshi, Ali (Supervisor) ; Ghannad, Mohammad Ali (Co-Advisor)
    Abstract
    Statistical studies indicate the fact that in Iran, like many other developing countries, a significant percentage of buildings are made of traditional materials and most of them are adobe buildings especially in rural areas. Furthermore, geological data indicates that Iran is located in alps-Himalayas seismic zone and exposed by destructive earthquakes and adobe buildings suffer the most damages comparing with other type of the structures. According to these explanations, this research deals with adobe buildings behavior and provides solutions for reinforcing them and improving the seismic response of these buildings. These studies include numerical modeling with finite elements methods by... 

    Parametric Study on Seismic Performance of Spherical RC Domes

    , M.Sc. Thesis Sharif University of Technology Gholamrezaie, Amir (Author) ; Vafaei, Abolhassan (Supervisor) ; Mofid, Massoud (Co-Advisor)
    Abstract
    The present parametric study discusses the effective factors on seismic performance of spherical RC domes. For this perpose, a series of domes with different spans, a variety of contact angles (the angle between the bottom of the sphere and the center of the sphere), openings with different areas and various support condition are studied. Then the value of response modification factor and it's components is determined to take into account the effect of each component. The results obtained indicated that the response modification factor increases as the contact angle enhances. However, the span of domes insignificantly affects the value of response modification factor.also analysis on domes... 

    Parametric Study of Simple Column-Base Connections under Cyclic Loading

    , M.Sc. Thesis Sharif University of Technology Ghaffari Cherati, Amir (Author) ; Mofid, Massoud (Supervisor)
    Abstract
    Column-base connections are one of the most important elements in steel structures which connect the steel frame to the foundation. Therefore, in structures erected in seismic areas, these connections are critical to convey cyclic inertia forces to the frame. In this research the author performed a parametric study utilizing Finite Elements Method (FEM) to investigate the connection’s cyclic behavior. Primarily, the modeling method is verified and calibrated by the use of available experimental data. Afterwards, the parametric computer models are made. Though some researchers have investigated similar connection types, some components’ parameters like the column’s dimensions have not been... 

    Design of Customized Cemented Stems for Hip Joint Arthroplasty Surgery in Patients with Severe Femoral Deformity

    , M.Sc. Thesis Sharif University of Technology Ebadi, Yashar (Author) ; Farahmand, Farzam (Supervisor)
    Abstract
    Hip replacement surgery is performed with the aim of relieving pain and restoring the normal function of the joint for patients who are in the final stages of arthritis. Standard prostheses offered by implant manufacturers come in a wide variety of models and sizes to meet the needs of patients. However, these commercial prostheses may not be suitable for patients with significant bony abnormalities, leading to implant instability and loosening. In such cases, a suitable solution is to use customized implants that are specifically designed to match the patient's unique anatomy. The purpose of this research was to design a customized cement stem for hip joint replacement surgery in patients... 

    Study of Shear Lag Effect on Non-rectangular RC Shear Walls

    , M.Sc. Thesis Sharif University of Technology Tabiee, Mohammad (Author) ; Khaloo, Alireza (Supervisor)
    Abstract
    The present study aims to evaluate the effect of the shear-lag on non-rectangular RC shear walls and develop equations to determine the axial stress and strain distributions and calculate the effective flange width. Research has shown that a non-rectangular shear wall under a lateral load experiences the largest axial stress and strain in the flange-web cojunction. This phenomenon is referred to as the shear-lag effect and reduces the bending capacity of the shear wall. As a result, the effective flange width is typically defined to consider the shear lag effect. The present work first reviewed the literature on the effects of shear lag on non-rectangular RC shear walls. Then, flanged shear... 

    Parametric Study of Unbonded Post Tensioned Precast Concrete Structural Walls Under Lateral Loading

    , M.Sc. Thesis Sharif University of Technology Sadeghi, Omid (Author) ; Kazemi, Mohammad Taghi (Supervisor)
    Abstract
    The use of unbonded post-tensioned precast concrete walls with horizontal joints as the primary lateral load resisting system in seismic zones has been considered in several previous studies. These walls are constructed by post-tensioning precast wall panels across horizontal joints using post-tensioning steel which is not bonded to the concrete. The behavior of the unbounded post-tensioned precast structural wall under lateral loads strongly depends on base panel geometry and concrete confinement properties. In this research an analytical parametric investigation on base panel design parameters is conducted using DRAIN-2DX software. Fiber beam-column elements are used to represent the... 

    Numerical Investigation of the Effects of Different Parameters on the Mechanical Response of Energy Pile under Cyclic Thermal Loading in Saturated Clay

    , M.Sc. Thesis Sharif University of Technology Sadeghzadeh, Mohammad Reza (Author) ; Ahmadi, Mohammad Mehdi (Supervisor)
    Abstract
    Considering the environmental pollution caused by the consumption of fossil fuels, replacing clean and renewable energies instead of fossil fuels has become one of the most critical issues across the world. The use of energy geostructures, especially energy piles, to exchange the heat between the superstructures and the ground is one of the approaches for taking advantage of clean energy. In order to maintain the safety and the serviceability of structures built on energy piles, it is necessary to study the effects of heat exchange between energy piles and the ground on the mechanical behavior of energy piles, as well as the effects of various parameters on the interaction between energy... 

    Numerical Optimization and Parametric Study of Cooperative Salvo Attack Using Particle Swarm Optimization Algorithm

    , M.Sc. Thesis Sharif University of Technology Shahadati, Mohammad (Author) ; Saghafi, Fariborz (Supervisor)
    Abstract
    In this research work, several guidance laws have been utilized and validated, considering the contraints on the missslie seeker angle and maximum acceleration, in order to simultaneously intercept the so-called Close-in Weapon System (CIWS) by multiple missiles. First of all, the existing guidance laws for salvo-attack are reveiwed. Then, a simulation program has been developed and validated for the misslie and CIWS as a five and two degrees of freedom systems, respectively. Optimization of the system is then carried out by the method of Particle Swarm Optimization, considering the given constraints. In the next step, for the improvement of the optimized guidance law, paramertic study has... 

    , M.Sc. Thesis Sharif University of Technology Seyfi, Sahand (Author) ; Pak, Ali (Supervisor)
    Abstract
    Lateral spreading is a common mode of earthquake-induced failure that usually occurs as a result of liquefaction in gently sloped sandy layers. Numerical simulation of this phenomenon requires fully coupled analysis of displacement of solid sand particles and pore water pressure under seismic loading. Predicting occurrence of initial liquefaction and sub-sequent ground movement requires employing an efficient and robust constitutive model that can predict the undrained behavior of saturated sand under different conditions. In this study, a fully coupled finite element code “PISA” utilizing a critical state two-surface plasticity constitutive model, proposed by Manzari and Dafalias (1997),... 

    A Parametric Study of Geosynthetic Reinforced Soil (GRS) Low Height Walls with Concrete Block Facing in FLAC Software

    , M.Sc. Thesis Sharif University of Technology Selseleh, Amin (Author) ; Pak, Ali (Supervisor)
    Abstract
    Because of seismic flexibility, aesthetics, economic advantage and rapid construction of reinforced soil walls, application of these walls has raised tremendously since 1970’s. The early reinforced soil retaining walls used metallic srips to reinforce the soil with precast concrete panels as facing, however, since 1990’s using of geosynthetics to reinforce these walls with modular concrete block facing have replaced the old fashion. In this study, a finite difference code was developed in FLAC software. After verification of the numerical modeling procedure, a wall with 3.6m height reinforced by geosynthetics was simulated. In the course of numerical simulations the stage of counstruction,... 

    On the Parametric Analysis of Structural Response of Base Plate Connections through FEM

    , M.Sc. Thesis Sharif University of Technology Khodaei, Sina (Author) ; Mofid, Masoud (Supervisor)
    Abstract
    Base plate is one of the important and sensitive elements of a structure which roles as a connector of force and moment in column to foundation joint and prevents from stress concentration in the joint area. As until now there has been several numerical and experimental researches conducted about base plate connections, but in practice for design, base plate is considered as a cantilever beam which undertakes compressive force and bending moment. In this method of design many important factors such as separation and deflection of base plate, interaction of base plate with bolts and foundation aren’t taken into consideration. Therefore there is an urgent need to design base plates considering... 

    Thermal-economic Modeling and Optimization of Ground-Coupled Heat Pump System for Various Climatic Conditions of Iran

    , M.Sc. Thesis Sharif University of Technology Tabarjafar Gholibisheh, Hamzeh (Author) ; Abbaspour Tehrani Fard, Madjid (Supervisor)
    Abstract
    The optimal design of a ground-coupled heat pump (GCHP) system with vertical ground heat exchanger (VGHX) includes thermal modeling of the system and selection of optimal design parameters is presented in this research. Then, by applying Nelder-Mead optimization algorithm, an objective function (Total Annual Cost which is the sum of annual investment and operating costs of the system) is defined and minimized, exposed to specified design constraints. Also, Genetic Algorithm is used to verify the optimal design process. In order to evaluate the accuracy of a presented model, the optimum values of a heat pump design parameters includes saturated temperature/pressure of a condenser and...