Loading...
Search for: parametric-study
0.007 seconds
Total 103 records

    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) Hamed, A ; 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... 

    Effects of concurrent earthquake and temperature loadings on cable-stayed bridges

    , Article International Journal of Structural Stability and Dynamics ; Volume 16, Issue 6 , 2016 ; 02194554 (ISSN) Maleki, S ; Maghsoudi Barmi, A ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd 
    Abstract
    This paper discusses the necessity of considering the concurrent effects of uniform temperature and earthquake loadings in the design of cable-stayed bridges. This load combination is not foreseen in current design standards such as AASHTO and Eurocode. Three-dimensional finite element models of cable-stayed bridges are employed for nonlinear time history analyses. A load combination is proposed that adds uniform temperature loading to the existing extreme event load combination. The proposed combination is compared with existing extreme event load combination and the changes in forces and displacements are noted. A parametric study is then conducted by varying a number of properties of the... 

    Numerical optimization and inverse study of a microfluidic device for blood plasma separation

    , Article European Journal of Mechanics, B/Fluids ; Volume 57 , 2016 , Pages 31-39 ; 09977546 (ISSN) Shamloo, A ; Vatankhah, P ; Bijarchi, M. A ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    In this paper, a passive microfluidic device for continuous real time blood plasma separation has been studied and optimized. A numerical model is used to solve both the fluid flow and the particles confined within it. Red blood cells are considered as particles with diameter of 7μm. A parametric study is performed in order to characterize the effect of different parameters on separation and purity efficiency. In this study, four different variables were introduced to design the microfluidic device for blood plasma separation including: the angle between the daughter channels and the main channel, the widths, the diffuse angle and the number of daughter channels. Results show that the... 

    Parametric study and design approach of off-center bracing systems

    , Article Structural Design of Tall and Special Buildings ; Volume 26, Issue 3 , 2017 ; 15417794 (ISSN) Sedaghati, P ; Lotfollahi, M ; Mofid, M ; Sharif University of Technology
    Abstract
    This paper presents an effective approach for the seismic design of off-center bracing systems (OBSs). The nonlinear behavior of an OBS can be specified by evaluation of two yielding stages representing tensile yielding of different bracings. This can be achieved when stiffness of the corner brace member is deliberately considered less enough to act as a fuse-like component. An accurate two-dimensional finite element modeling for the geometric and material nonlinearity of such systems considering buckling behavior of the brace members is developed. Through an extensive parametric study, the optimal ratios of the influential parameters of OBS are obtained, and their effects on the nonlinear... 

    Local and global buckling condition of all-steel buckling restrained braces

    , Article Steel and Composite Structures ; Volume 23, Issue 2 , 2017 , Pages 217-228 ; 12299367 (ISSN) Mirtaheri, S. M ; Nazeryan, M ; Bahrani, M. K ; Nooralizadeh, A ; Montazerian, L ; Naserifard, M ; Sharif University of Technology
    Techno Press  2017
    Abstract
    Braces are one of the retrofitting systems of structure under earthquake loading. Buckling restrained braces (BRBs) are one of the very efficient braces for lateral loads. One of the key needs for a desirable and acceptable behavior of buckling-restraining brace members under intensive loading is that it prevents total buckling until the bracing member tolerates enough plastic deformation and ductility. This paper presents the results of a set of analysis by finite element method on buckling restrained braces in which the filler materials within the restraining member have been removed. These braces contain core as the conventional BRBs, but they have a different buckling restrained system.... 

    Shear behavior of ultra-high performance concrete

    , Article Construction and Building Materials ; Volume 183 , 2018 , Pages 554-564 ; 09500618 (ISSN) Pourbaba, M ; Joghataie, A ; Mirmiran, A ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    The application of ultra-high performance concrete (UHPC) as an alternative to conventional/normal concrete (NC) has grown rapidly in recent years. However, there is limited knowledge on its shear behavior, which is essential for developing design guidelines for structural applications. A detailed parametric study was conducted on 38 beam specimens, half of which were made of UHPC and the other half made of NC. To ensure applicability of findings, two types of UHPC mixes were used, a proprietary and a generic mix. Eighteen of the beams were prepared and tested in Tabriz, Iran, while the other 20 were made and tested in Miami, FL. Test parameters included type of concrete (UHPC and NC), shear... 

    Simulation and performance improvement of cryogenic distillation column, using enhanced predictive Peng–Robinson equation of state

    , Article Fluid Phase Equilibria ; Volume 489 , 2019 , Pages 117-130 ; 03783812 (ISSN) Ardeshir Larijani, M ; Bayat, M ; Afshin, H ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    In this study, a cryogenic distillation column has been designed and simulated via a computer code based on the theta method of convergence. The required thermodynamic properties are determined from the enhanced predictive Peng-Robinson (E-PPR 78) equation of state which has a good accuracy in predicting the corresponding thermodynamic properties of natural gas components. The combined code of distillation column/equation of state has been verified with that of another study. In the present study, the results are achieved by the constant molar over-flow and inclusion of energy equations assumptions. In order to have more accuracy in the results, the energy equations were considered in the... 

    A numerical investigation on natural convection heat transfer in annular-finned concentric horizontal annulus using nanofluids: a parametric study

    , Article Heat Transfer Engineering ; 2020 Ashouri, M ; Zarei, M. M ; Hakkaki Fard, A ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to 9 (Formula presented.) 105, were studied. The obtained results revealed that Al2O3-water nanofluid has the highest heat transfer rate. The calculated heat transfer rates for Al2O3-water nanofluid for Rayleigh numbers of 9 (Formula presented.) 105, 105, and 104 were respectively up to 12.1%, 26.2%, and 31.6%... 

    A parametric study on optimal shape of buckling restrained knee bracing frames

    , Article 5th International Conference on Advances in Steel Structures, ICASS 2007, Singapore, 5 December 2007 through 7 December 2007 ; Volume 3 , 2007 , Pages 356-361 ; 9789810593711 (ISBN) Lotfollahi, M ; Mofid, M ; Sharif University of Technology
    2007
    Abstract
    This paper is concerned with the development of buckling-restrained knee bracing frames for seismic design and retrofit of steel frame structures. Analytical models based on the new nonlinear finite element modeling of the system for the moment and shear yielding mode were developed in a structure with buckling-restrained knee-braces. Parametric study was performed with new and practical parameters of the system describing the specification of the system in elastic and inelastic behavior; and the results are shown in form of the appropriate graphs and charts. This study makes an offer to a simple design technique for this type of structure with a bilinear approach, using a nonlinear finite... 

    A numerical investigation on natural convection heat transfer in annular-finned concentric horizontal annulus using nanofluids: a parametric study

    , Article Heat Transfer Engineering ; Volume 42, Issue 22 , 2021 , Pages 1926-1948 ; 01457632 (ISSN) Ashouri, M ; Zarei, M. M ; Hakkaki Fard, A ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    Abstract
    Natural convection heat transfer in a concentric horizontal annulus with annular fins is numerically studied. Due to the low thermal conductivity of water, CuO-water and Al2O3-water nanofluids were used as heat transfer fluids. The effect of three different parameters, including fin spacing, fin eccentricity, and fin thickness at different fin diameters and Rayleigh number range of 104 to 9 (Formula presented.) 105, were studied. The obtained results revealed that Al2O3-water nanofluid has the highest heat transfer rate. The calculated heat transfer rates for Al2O3-water nanofluid for Rayleigh numbers of 9 (Formula presented.) 105, 105, and 104 were respectively up to 12.1%, 26.2%, and 31.6%... 

    Experimental and numerical evaluation of the mechanical characteristics of semi-rigid saddle connections

    , Article Structural Design of Tall and Special Buildings ; Volume 31, Issue 7 , 2022 ; 15417794 (ISSN) Moghaddam, H ; Sadrara, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2022
    Abstract
    Saddle connections are semi-rigid connections that are widely used in Iran. Many existing buildings contain this type of connection. The present study conducted full-scale experiments and used extensive numerical modeling to study the mechanical characteristics of saddle connections. The mechanical characteristics examined were the moment-transfer mechanism, initial stiffness, yield moment, maximum moment, and fracture rotation. The configuration and dimensions of the experimental and numerical specimens were chosen to be similar to those of saddle connections in existing buildings. A parametric study was conducted to determine the factors affecting the mechanical characteristics of these... 

    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... 

    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 study of the effects of process parameters on tool life in a cold radial forging process

    , Article Scientia Iranica ; Vol. 21, issue. 2 , 2014 , p. 339-346 Afrasiab, H ; Movahhedy, M. R ; Sharif University of Technology
    Abstract
    Radial forging is an open die forging process used for reducing the diameters of shafts, tubes, stepped shafts and axles, and for creating internal profiles in tubes. Due to very large forging loads, the tool should withstand high stress and wear. Therefore, the success of the forging process depends upon recognition of the die failure factors and optimization of the tool working conditions that enhance tool life. In this study, the effect of process parameters on tool life in the cold radial forging process is investigated using nonlinear three dimensional finite element modeling. Wear and mechanical fatigue are considered as the main modes of tool failure, and a parametric study on the... 

    Application of elastically supported single-walled carbon nanotubes for sensing arbitrarily attached nano-objects

    , Article Current Applied Physics ; Volume 13, Issue 1 , 2013 , Pages 107-120 ; 15671739 (ISSN) Kiani, K ; Ghaffari, H ; Mehri, B ; Sharif University of Technology
    Abstract
    The potential application of SWCNTs as mass nanosensors is examined for a wide range of boundary conditions. The SWCNT is modeled via nonlocal Rayleigh, Timoshenko, and higher-order beam theories. The added nano-objects are considered as rigid solids, which are attached to the SWCNT. The mass weight and rotary inertial effects of such nanoparticles are appropriately incorporated into the nonlocal equations of motion of each model. The discrete governing equation pertinent to each model is obtained using an effective meshless technique. The key factor in design of a mass nanosensor is to determine the amount of frequency shift due to the added nanoparticles. Through an inclusive parametric... 

    Equivalent linearization of non-linear soil-structure systems

    , Article Earthquake Engineering and Structural Dynamics ; Volume 41, Issue 13 , 2012 , Pages 1775-1792 ; 00988847 (ISSN) Esmaeilzadeh Seylabi, E ; Jahankhah, H ; Ghannad, M. A ; Sharif University of Technology
    Wiley  2012
    Abstract
    The concept of equivalent linearization, in which the actual nonlinear structure is replaced by an equivalent linear single-degree-of-freedom (SDOF) system, is extended for soil-structure systems in order to consider the simultaneous effects of soil-structure interaction (SSI) and inelastic behavior of the structure on equivalent linear parameters (ELP). This is carried out by searching over a two-dimensional equivalent period-equivalent damping space for the best pair, which can predict the earthquake response of the inelastic soil-structure system with sufficient accuracy. The super-structure is modeled as an elasto-plastic SDOF system whereas the soil beneath the structure is considered... 

    Assessment of a practical technique for active control of sound using microphone and speaker

    , Article Scientia Iranica ; Volume 19, Issue 4 , 2012 , Pages 1005-1012 ; 10263098 (ISSN) Joghataie, A ; Raoufi, M ; Sharif University of Technology
    Elsevier  2012
    Abstract
    In this analytical study, it has been desired to develop a practical and simple control mechanism to control, at a given point and its neighborhood, the sound arriving from a distant source, assuming that a primary pure-tone sound pressure is propagated from a relatively far distance. The control model consists of a microphone as a sensor for measuring the sound pressure and a loud speaker for applying the control force. Corresponding equations have been developed to determine an optimum control force, and afterwards a parametric study on the factors affecting the control results has been performed. The results show that the control system can significantly reduce low frequency sound... 

    A parametric study using two design methodologies for pressure jet and swirl injectors

    , Article IEEE Aerospace Conference Proceedings ; 2012 ; 1095323X (ISSN) ; 9781457705564 (ISBN) Mazaheri, K ; Morad, M. R ; Shakeri, A. R ; Sharif University of Technology
    2012
    Abstract
    One of the most important subsystems in the air-breathing engines is the atomizers, which break the fuel into many droplets. It is well known that atomization quality has a significant influence on combustion characteristics such as stability limits, efficiency, and pollutant emission. Both jet and swirl injectors are applicable in gas turbine engines. The latter have been widely used for combustion chambers and the former are usually employed for fuel injection in the afterburner part. Since experimental and numerical study of atomizers could be complex and costly, a design methodology of atomizers based on empirical relations is still very advantageous and effective in reducing... 

    Analysis of nanofluid heat transfer in parallel-plate vertical channels partially filled with porous medium

    , Article International Journal of Thermal Sciences ; Volume 55 , 2012 , Pages 103-113 ; 12900729 (ISSN) Hajipour, M ; Molaei Dehkordi, A ; Sharif University of Technology
    Abstract
    In this article, mixed-convective heat transfer of nanofluids in a vertical channel partially filled with highly porous medium was studied. In the porous region, the Brinkman-Forchheimer extended Darcy model was used to describe the fluid flow pattern. Different viscous dissipation models were also applied to account for viscous heating. At the porous medium-fluid interface, interfacial coupling conditions for the fluid velocity and temperature were used to derive the analytical solution using a two-parameter perturbation method. The model used for the nanofluids incorporates the effects of Brownian motion and thermophoresis. With constant wall temperature, velocity and temperature profiles... 

    Dynamics of a delaminated timoshenko beam subjected to a moving oscillatory mass

    , Article Mechanics Based Design of Structures and Machines ; Volume 40, Issue 2 , Apr , 2012 , Pages 218-240 ; 15397734 (ISSN) Kargarnovin, M. H ; Ahmadian, M. T ; Jafari-Talookolaei, R. A ; Sharif University of Technology
    2012
    Abstract
    This paper presents dynamic response of a delaminated composite beam under the action of moving oscillatory mass. The Poisson's effect, shear deformation and rotary inertia have been considered in this analysis. We have used the constrained mode model to simulate the behavior between the delaminated surfaces. Based on this model, eigen-solution technique is used to obtain the natural frequencies and their corresponding mode shapes for the delaminated beam. Then, the forced response is determined by employing the modal series expansion technique. The obtained results for the free and forced vibrations of beams are verified against reported similar results in the literature. Moreover, the...