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Total 103 records

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; 2017 , Pages 1-8 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    Abstract
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity. © 2017 Taylor... 

    Experimental study of onset of subcooled annular flow boiling

    , Article Progress in Nuclear Energy ; Volume 51, Issue 2 , 2009 , Pages 361-365 ; 01491970 (ISSN) Ahmadi, R ; Nouri Borujerdi, A ; Jafari, J ; Tabatabaei, I ; Sharif University of Technology
    2009
    Abstract
    An experimental study on the onset of nucleate boiling (ONB) is performed for water annular flow to provide a systematic database for low pressure and velocity conditions. A parametric study has been conducted to investigate the effect of pressure, inlet subcooling, heat and mass flux on flow boiling. The test section includes a Pyrex tube with 21 mm inner diameter and a stainless steel (SS-304) rod with outer diameter of 6 mm. Pressure, heat and mass flux are in the range of 1.73 < P < 3.82 bar, 40 < q < 450 kW/m2 and 70 < G < 620 kg/m2 s, respectively. The results illustrate that inception heat flux is extremely dependent on pressure, inlet subcooling temperature and mass flux; for example... 

    Experimental and analytical study on channel shear connectors in fiber-reinforced concrete

    , Article Journal of Constructional Steel Research ; Volume 65, Issue 8-9 , 2009 , Pages 1787-1793 ; 0143974X (ISSN) Maleki, S ; Mahoutian, M ; Sharif University of Technology
    2009
    Abstract
    This paper investigates, experimentally and analytically, the capacity of channel shear connectors embedded in normal and polypropylene (PP) concrete. Limited testing is used to assess the accuracy of a proposed nonlinear finite element model for typical push-out test specimens. Using this model, an extensive parametric study is performed to arrive at a prediction for shear capacity of channel connectors in PP concrete. An equation, for inclusion in design codes, is suggested for the shear capacity of these connectors when used in PP concrete. © 2009 Elsevier Ltd. All rights reserved  

    Proposal and assessment of a new geothermal-based multigeneration system for cooling, heating, power, and hydrogen production, using LNG cold energy recovery

    , Article Renewable Energy ; Volume 135 , 2019 , Pages 66-87 ; 09601481 (ISSN) Ebadollahi, M ; Rostamzadeh, H ; Zamani Pedram, M ; Ghaebi, H ; Amidpour, M ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    Multigeneration systems (MGSs) driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based MGS is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas (LNG) as cold energy recovery. The system is composed of an organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), an LNG power generation system, and a proton exchange membrane (PEM) electrolyzer system. To demonstrate the feasibility of the proposed MGS, energy, exergy, and exergoeconomic analysis are employed as the most effective tools... 

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; Volume 26, Issue 4 , 2019 , Pages 333-340 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    Taylor and Francis Inc  2019
    Abstract
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity  

    Computational predictions for estimating the maximum deflection of reinforced concrete panels subjected to the blast load

    , Article International Journal of Impact Engineering ; Volume 139 , 2020 Shishegaran, A ; Khalili, M. R ; Karami, B ; Rabczuk, T ; Shishegaran, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    We investigate the resistance of reinforced concrete panels (RCPs) due to explosive loading using nonlinear finite element analysis and surrogate models. Therefore, gene expression programming model (GEP), multiple linear regression (MLR), multiple Ln equation regression (MLnER), and their combination are used to predict the maximum deflection of RCPs. The maximum positive and negative errors, mean of absolute percentage error (MAPE), and statistical parameters such as the coefficient of determination, root mean square error (RMSE). Normalized square error (NMSE), and fractional bias are utilized to evaluate and compare the performance of the models. We also present a novel statistical table... 

    Using the fluid/structure interaction to mitigate the seismic response of structures equiped with cylindrical liquid tanks subjected to near field earthquakes

    , Article 11th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC-11, Taipei, 19 November 2008 through 21 November 2008 ; 2008 Attari, N. K. A ; Rofooei, F. R ; Sharif University of Technology
    2008
    Abstract
    Seismic response of a Single Degree of Freedom (SDOF) system containing a rigid circular cylindrical liquid tank under the earthquake excitations is considered in the presence of fluid/structure interaction. The governing differential equations of the system is derived considering the first three liquid sloshing modes (1, 1), (0, 1) and (2, 1) under different strong ground motions. The dynamic response of the system is investigated in the neighborhood of 1:1 and 1:2 internal resonances between the SDOF system and the liquid sloshing modes. These internal resonances take place by tuning the frequency of the first asymmetric sloshing mode of the liquid to the fundamental frequency of the SDOF... 

    Behavior of channel shear connectors, Part II: Analytical study

    , Article Journal of Constructional Steel Research ; Volume 64, Issue 12 , December , 2008 , Pages 1341-1348 ; 0143974X (ISSN) Maleki, S ; Bagheri, S ; Sharif University of Technology
    2008
    Abstract
    In this second part of the two companion papers an effective numerical model is proposed using finite element method to simulate the push-out test of channel shear connectors. The focus is on the shear capacity of channel shear connectors embedded in a solid reinforced concrete slab under monotonic loading. The model has been validated against test results presented in Part (I) and compared with data given in North American design codes. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength, channel dimensions and the orientation of the channel. The results show that the concrete strength, web and flange thicknesses of the channel and... 

    Large deformation finite element modeling of rubble mound breakwater built on soft seabed using coupled eulerian–lagrangian method

    , Article Indian Geotechnical Journal ; Volume 51, Issue 2 , 2021 , Pages 315-328 ; 09719555 (ISSN) Masoudi, S ; Shahir, H ; Pak, A ; Sharif University of Technology
    Springer  2021
    Abstract
    For the design of rubble mound breakwaters on soft soil, it is essential to predict the behavior of soft soil and large deformations phenomena occurring in the course of construction of the rubble mound breakwater. Large deformations in various problems can be well simulated using the coupled Eulerian–Lagrangian (CEL) method. In this study, the CEL method has been used to simulate the rubble mounds construction on soft soil and predict the resulting settlements. To validate the numerical model, the results of three experiments conducted in the physical modeling laboratory at Kharazmi University were used. Also, two case studies of real rubble mound breakwaters constructed on soft seabeds... 

    Estimation of the compressive strength of green concretes containing rice husk ash: a comparison of different machine learning approaches

    , Article European Journal of Environmental and Civil Engineering ; 2022 ; 19648189 (ISSN) Tavana Amlashi, A ; Mohammadi Golafshani, E ; Ebrahimi, S. A ; Behnood, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    To mitigate the environmental issues related to the utilisation of ordinary portland cement (OPC) in concrete mixtures, attempts have been carried out to find alternative binders such as rice husk ash (RHA) as replacements for OPC. This study contributes to moving from the traditional laboratory-based methods for the determination of compressive strength (CS) towards machine learning-based approaches by developing three accurate models (i.e. artificial neural network (ANN), multivariate adaptive regression spline (MARS) and M5P model tree) for the estimation of the CS of concretes containing RHA. For this purpose, the models were developed employing 909 data records collected through... 

    Micro-plasma actuator mechanisms in interaction with fluid flow for wind energy applications: operational parameters

    , Article Engineering with Computers ; 2022 ; 01770667 (ISSN) Omidi, J ; Mazaheri, K ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    Plasma actuator is a flow control device which may be used to improve the performance of wind turbine blades at low airspeeds. One of the most robust numerical models to simulate the interaction of the plasma actuator with the fluid flow is the electrostatic model. This model is improved by the authors. Due to the high cost of performing experimental optimization, the optimization of plasma actuators may be investigated by this numerical model. To optimize the aerodynamic performance of a Delft University (DU) wind turbine airfoil in a full stall condition, we used the operational parameters (voltage, frequency and the waveform) applied to the plasma actuator as the main design variables. We... 

    Investigation of the effects of geometrical parameters, eccentricity and perforated fins on natural convection heat transfer in a finned horizontal annulus using three dimensional lattice Boltzmann flux solver

    , Article International Journal of Numerical Methods for Heat and Fluid Flow ; Volume 32, Issue 1 , 2022 , Pages 283-312 ; 09615539 (ISSN) Ashouri, M ; Zarei, M. M ; Moosavi, A ; Sharif University of Technology
    Emerald Publishing  2022
    Abstract
    Purpose: The purpose of this paper is to investigate the effects of geometrical parameters, eccentricity and perforated fins on natural convection heat transfer in a finned horizontal annulus using three-dimensional lattice Boltzmann flux solver. Design/methodology/approach: Three-dimensional lattice Boltzmann flux solver is used in the present study for simulating conjugate heat transfer within an annulus. D3Q15 and D3Q7 models are used to solve the fluid flow and temperature field, respectively. The finite volume method is used to discretize mass, momentum and energy equations. The Chapman–Enskog expansion analysis is used to establish the connection between the lattice Boltzmann equation... 

    Dynamic responses of intervertebral disc during static creep and dynamic cyclic loading: A parametric Poroelastic finite element analysis

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 25, Issue 1 , 2013 ; 10162372 (ISSN) Nikkhoo, M ; Haghpanahi, M ; Parnianpour, M ; Wang, J. L ; Sharif University of Technology
    2013
    Abstract
    Low back pain is a common reason for activity limitation in people younger than 45 years old, and was proved to be associated with heavy physical works, repetitive lifting, impact, stationary work postures and vibrations. The study of load transferring and the loading condition encountered in spinal column can be simulated by finite element models. The intervertebral disc is a structure composed of a porous material. Many physical models were developed to simulate this phenomenon. The confounding effects of poroelastic properties and loading conditions on disc mechanical responses are, nevertheless, not cleared yet. The objective of this study was to develop an axisymmetric poroelastic... 

    Electroosmotic flow of viscoelastic fluids through a slit microchannel with a step change in wall temperature

    , Article Journal of Heat Transfer ; Volume 135, Issue 2 , 2013 ; 00221481 (ISSN) Sadeghi, A ; Veisi, H ; Saidi, M. H ; Asghar Mozafari, A ; Sharif University of Technology
    2013
    Abstract
    Thermally developing electroosmotically generated flow of two viscoelastic fluids, namely the PTT and FENE-P models, through a slit microchannel is considered. Both the viscous dissipation and Joule heating effects are taken into account and a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the resultant eigenvalue problem is solved numerically; nevertheless, an analytical solution is presented for the regions close to the entrance. A parametric study reveals that increasing amounts of the Peclet number... 

    Electrokinetically driven fluidic transport of power-law fluids in rectangular microchannels

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 414 , 2012 , Pages 440-456 ; 09277757 (ISSN) Vakili, M. A ; Sadeghi, A ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
    2012
    Abstract
    Electroosmosis is the predominant mechanism for flow generation in lab-on-chip devices. Since most biofluids encountered in these devices are considered to be non-Newtonian, it is vital to study the flow characteristics of common non-Newtonian models under electroosmotic body force. In this paper, the hydrodynamically fully developed electroosmotic flow of power-law fluids in rectangular microchannels is analyzed. The electrical potential and momentum equations are numerically solved through a finite difference procedure for a non-uniform grid. A thoroughgoing parametric study reveals that the Poiseuille number is an increasing function of the channel aspect ratio, the zeta potential, the... 

    Thermally developing electroosmotic flow of power-law fluids in a parallel plate microchannel

    , Article International Journal of Thermal Sciences ; Volume 61 , 2012 , Pages 106-117 ; 12900729 (ISSN) Sadeghi, A ; Saidi, M.H ; Veisi, H ; Fattahi, M ; Sharif University of Technology
    2012
    Abstract
    The present investigation considers the thermally developing electroosmotic flow of power-law fluids through a parallel plate microchannel. Both the viscous dissipation and Joule heating effects are taken into account and a step change in wall temperature is considered to represent physically conceivable thermal entrance conditions. Expressions for the dimensionless temperature and Nusselt number in the form of infinite series are presented. In general, the resultant eigenvalue problem is solved numerically; nevertheless, an analytical solution is presented for the regions close to the entrance. A parametric study reveals that increasing amounts of the Peclet number result in higher wall... 

    Thermodynamic model for prediction of performance and emission characteristics of SI engine fuelled by gasoline and natural gas with experimental verification

    , Article Journal of Mechanical Science and Technology ; Volume 26, Issue 7 , July , 2012 , Pages 2213-2225 ; 1738494X (ISSN) Mehrnoosh, D ; Asghar, H. A ; Asghar, M. A ; Sharif University of Technology
    2012
    Abstract
    In this study, a thermodynamic cycle simulation of a conventional four-stroke SI engine has been carried out to predict the engine performance and emissions. The first law of thermodynamics has been applied to determine in-cylinder temperature and pressure as a function of crank angle. The Newton-Raphson method was used for the numerical solution of the equations. The non-differential form of equations resulted in the simplicity and ease of the solution to predict the engine performance. Two-zone model for the combustion process simulation has been used and the mass burning rate was predicted by simulating spherical propagation of the flame front. Also, temperature dependence of specific... 

    The effect of foundation embedment on inelastic response of structures

    , Article Earthquake Engineering and Structural Dynamics ; Volume 38, Issue 4 , 2009 , Pages 423-437 ; 00988847 (ISSN) Mahsuli, M ; Ghannad, M. A ; Sharif University of Technology
    John Wiley and Sons Ltd  2009
    Abstract
    In this research, a parametric study is carried out on the effect of soil-structure interaction on the ductility and strength demand of buildings with embedded foundation. Both kinematic interaction (KI) and inertial interaction effects are considered. The sub-structure method is used in which the structure is modeled by a simplified single degree of freedom system with idealized bilinear behavior. Besides, the soil sub-structure is considered as a homogeneous half-space and is modeled by a discrete model based on the concept of cone models. The foundation is modeled as a rigid cylinder embedded in the soil with different embedment ratios. The soil-structure system is then analyzed subjected... 

    Parametric analyses of multispan viscoelastic shear deformable beams under excitation of a moving mass

    , Article Journal of Vibration and Acoustics, Transactions of the ASME ; Volume 131, Issue 5 , 2009 , Pages 0510091-05100912 ; 10489002 (ISSN) Kiani, K ; Nikkhoo, A ; Mehri, B ; Sharif University of Technology
    2009
    Abstract
    This paper presents a numerical parametric study on design parameters of multispan viscoelastic shear deformable beams subjected to a moving mass via generalized moving least squares method (GMLSM). For utilizing Lagrange's equations, the unknown parameters of the problem are stated in terms of GMLSM shape functions and the generalized Newmark-β scheme is applied for solving the discrete equations of motion in time domain. The effects of moving mass weight and velocity, material relaxation rate, slenderness, and span number of the beam on the design parameters and possibility of mass separation from the base beam are scrutinized in some detail. The results reveal that for low values of beam... 

    Dynamic behavior of pile foundations under cyclic loading in liquefiable soils

    , Article Computers and Geotechnics ; Volume 40 , 2012 , Pages 114-126 ; 0266352X (ISSN) Rahmani, A ; Pak, A ; Sharif University of Technology
    Abstract
    In this paper, a fully coupled three-dimensional dynamic analysis is carried out to investigate the dynamic behavior of pile foundations in liquefied ground. A critical state bounding surface plasticity model is used to model soil skeleton, while a fully coupled (u- P) formulation is employed to analyze soil displacements and pore water pressures. Furthermore, in this study, variation of permeability coefficient during liquefaction is taken into account; the permeability coefficient is related to excess pore water pressure ratio. Results of a centrifuge test on pile foundations are used to demonstrate the capability of the model for reliable analysis of piles under dynamic loading. Then, the...