Loading...
Search for: dynamic-loads
0.006 seconds
Total 66 records

    Physical Modeling to Iimpact of Burial Depth of Pipe in Soil Slopes Under Dynamic Loading

    , M.Sc. Thesis Sharif University of Technology Derakhshan Ghazani, Reza (Author) ; Jafarzadeh, Fardin (Supervisor)
    Abstract
    Buried pipelines as vital arteries,which will play a major role in human life should be designed and implemented in such a way that withstand the least possible harm with regard economic issues.In this study we tried to use a physical model, the impact of pipeline buried in soil slope under dynamic load are examined.To achive this goal we use a rigid metal bax with dimensions of 301.5*101.5*155 cubic meters for modeling. Pipes used in these experiments has a diameter of 1.6 cm which are connected by a fulcrum to the wall box. In order to measure strain generated in the pipe we use a series of strain gauges that were installed using the pipe at some points. Physical models made on Sharif... 

    Coupled effects of suction and degree of saturation on large strain shear modulus of unsaturated sands

    , Article Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014 ; Vol. 2, issue , July , 2014 , p. 1559-1564 ; 978-1-138-00150-3 Jafarzadeh, F ; Ahmadinezhad, A ; Sadeghi, H ; Sharif University of Technology
    Abstract
    Predictions of soil behavior in response to dynamic loads require an understanding of dynamic properties of soil. Studies on dynamic properties of unsaturated soils at large-strains are quite limited, while some dynamic loadings, like earthquakes, are in the medium to large-strain ranges. A cyclic simple shear apparatus was developed to measure large-strain shear modulus and damping ratio under different matric suction or degree of saturation. Six cyclic tests, with referring to the soil-water retention curve, were conducted on clean medium sand. Results indicated that shear modulus slightly increases when suction varies from zero up to the air entry value. Approaching the residual value, a... 

    Influence of imperfection on amplitude and resonance frequency of a reinforcement compositionally graded nanostructure

    , Article Waves in Random and Complex Media ; 2019 ; 17455030 (ISSN) Hashemi, H. R ; Alizadeh, A ; Oyarhossein, M. A ; Shavalipour, A ; Makkiabadi, M ; Habibi, M ; Sharif University of Technology
    Taylor and Francis Ltd  2019
    Abstract
    This article investigates the influences of nonuniform imperfection on the dynamic amplitude and resonance frequency of the nanoshell reinforced with graphene nanoplatelet (GNP). The novelty of the current study is to consider the effects of porosity, thermal loading and graphene platelet reinforced composites on the dynamic behavior of the nanostructure. Three-length scale parameters (l0=5 h, l1=3 h, l2=5 h) in the modified strain gradient theory (MSGT) show a better agreement with MD simulation in comparison with other theories. Finally, the effects of different factors on the dynamic amplitude and resonance frequency of the porous nanostructure are examined in detail. © 2019, © 2019... 

    Dynamic parameters of dry sand using one dimensional shaking table tests

    , Article 6th International Conference on Physical Modelling in Geotechnics, ICPMG'06, Hong Kong, 4 August 2006 through 6 August 2006 ; Volume 1-2 , 2006 , Pages 279-283 ; 041541587X (ISBN); 9780415415873 (ISBN) Jafarzadeh, F ; Torghabeh, E. A ; Farahi Jahromi, H ; Sharif University of Technology
    2006
    Abstract
    In this paper the dynamic properties of Babolsar dry sand was investigated through one dimensional shaking table tests. 8 models of Babolsar loose dry sand under low confining pressures, were subjected to different harmonic and irregular dynamic loadings. The container was a laminar shear box having 24 layers each moving on the lower one. The dynamic properties including shear wave velocity, maximum shear modulus and damping ratio of the samples were addressed in this project. © 2006 Taylor & Francis Group, London  

    Parasite cloud service providers: on-demand prices on top of spot prices

    , Article Heliyon ; Volume 5, Issue 11 , 2019 ; 24058440 (ISSN) Haghshenas, H ; Habibi, J ; Fazli, M. A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    On-demand resource provisioning and elasticity are two of the main characteristics of the cloud computing paradigm. As a result, the load on a cloud service provider (CSP) is not fixed and almost always a number of its physical resources are not used, called spare resources. As the CSPs typically don't want to be overprovisioned at any time, they procure physical resources in accordance to a pessimistic forecast of their loads and this leads to a large amount of spare resources most of the time. Some CSPs rent their spare resources with a lower price called the spot price, which varies over time with respect to the market or the internal state of the CSP. In this paper, we assume the spot... 

    Design of bolted joints in pressure vessels by dynamic modelling

    , Article Proceedings of the Eight International Conference on Civil and Structural Engineering Computing, Vienna, 19 September 2001 through 21 September 2001 ; 2001 , Pages 123-124 ; 0948749768 (ISBN) Ghorashi, M ; Sharif University of Technology
    2001
    Abstract
    The dynamic behavior of a closure bolting system was predicted using a spring-mass-damper model. The loading was assumed to be an initially peaked, exponentially decaying internal pressure pulse acting on the closure. It was observed that optimal pre-stress values that minimized the peak bolt deformation and stress, existed for relatively high levels of applied force and low pre- stress  

    Development of a water brake dynamometer with regard to the modular product design methodology

    , Article ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis, ESDA 2014 ; Vol. 1, issue , July , 2014 , 25–27 Torabnia, S ; Banazadeh, A ; Sharif University of Technology
    Abstract
    This paper summarizes a research project in the field of design and manufacturing of a water brake dynamometer for power testing facilities. In the current study, the design process of a water brake with drilled rotor disks is presented. This process is examined against the development of a water brake for a 4MW gas turbine power measurement at 15,000 RPM speed. The proposed algorithm is based on vital assumptions such as; applying product designing issues and limited modular analysis that urges the disciplinary attitude and leads to the possibility of rapid development, easy maintenance and ease of access. The final scheme is divided into six disciplines with functional classification.... 

    Design and application of a new tapered superelement for analysis of revolving geometries

    , Article Finite Elements in Analysis and Design ; Volume 47, Issue 11 , November , 2011 , Pages 1242-1252 ; 0168874X (ISSN) Ahmadian, M. T ; Movahhedy, M. R ; Rezaei, M. M ; Sharif University of Technology
    2011
    Abstract
    Structures of tapered geometry are customarily used in a variety of applications. The analysis of such structures is usually made through finite element method using traditional beam, shell or brick elements. In this paper, a new tapered superelement is presented that lends itself to modeling revolving geometries under lateral, axial and torsional loads. The presented tapered superelement has 16 nodes. The performance of this element under static and dynamic loading and in rotating condition is examined. It is shown that this element yields accurate results with higher computational efficiency compared to conventional elements. Furthermore, it is verified that a single tapered superelement... 

    Matrix analysis of nonlinear trusses using Prandtl-2 neural networks

    , Article Journal of Sound and Vibration ; Volume 330, Issue 20 , 2011 , Pages 4813-4826 ; 0022460X (ISSN) Joghataie, A ; Farrokh, M ; Sharif University of Technology
    2011
    Abstract
    A new method, based on the concepts of matrix analysis as well as the learning capabilities of neural networks, for the analysis of nonlinear trusses under dynamic loading is presented. The method can be applied to static trusses too. While there have been attempts in the past to use neural networks to identify and model different structures based on data measured on structural response directly, the main feature and advantage of this new method is in its capability to model a nonlinear truss by assembling the data collected on the response of its members. The basics of the method are: (1) for each truss member, a neural network is trained to learn and simulate its loadresponse behavior, (2)... 

    Enhancing the structural performance of masonry arch bridges with ballast mats

    , Article Journal of Performance of Constructed Facilities ; Volume 31, Issue 5 , 2017 ; 08873828 (ISSN) Mohammadzadeh, S ; Miri, A ; Nouri, M ; Sharif University of Technology
    Abstract
    A large portion of the railway bridge stock in many countries is comprised of masonry arch bridges. During recent years, more attention has been paid to the maintenance of such structures. Rehabilitation and retrofitting methods have been proposed to enhance the performance of masonry arch bridges and extend their service life. Because a large portion of forces exerted on such structures comes from the railway track and passing trains, structural elements are added to the track to reduce the forces transmitted to bridges. One such element is the ballast mat, which, according to suppliers, has a positive impact on the structural performance of the track. This paper tries to assess the effects... 

    Effect of size dependency on in-plane vibration of circular micro-rings

    , Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1996-2008 ; 10263098 (ISSN) Karimzadeh, A ; Ahmadian, M. T ; Rahaeifard, M ; Sharif University of Technology
    Sharif University of Technology  2017
    Abstract
    In this paper, based on the modified couple stress theory, the size-dependent dynamic behavior of circular rings on elastic foundation is investigated. The ring is modeled by Euler-Bernoulli and Timoshenko beam theories, and Hamilton's principle is utilized to derive the equations of motion and boundary conditions. The formulation derived is a general form of the equation of motion of circular rings and can be reduced to the classical form by eliminating the size-dependent terms. On this basis, the size-dependent natural frequencies of a circular ring are calculated based on the non-classical Euler-Bernoulli and Timoshenko beam theories. The findings are compared with classical beam... 

    Effect of Porosity on free and forced vibration characteristics of the GPL reinforcement composite nanostructures

    , Article Computers and Mathematics with Applications ; Volume 77, Issue 10 , 2019 , Pages 2608-2626 ; 08981221 (ISSN) Pourjabari, A ; Esmailpoor Hajilak, Z ; Mohammadi, A ; Habibi, M ; Safarpour, H ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    This article investigates the influence of porosity on free and forced vibration characteristics of a nanoshell reinforced by graphene platelets (GPL). The material properties of piece-wise graphene-reinforced composites (GPLRCs) are assumed to be graded in the thickness direction of a cylindrical nanoshell and estimated using a nanomechanical model. In addition, because of imperfection of the current structure, three kinds of porosity distributions are considered. The nanostructure is modeled using modified strain gradient theory (MSGT) which is a size-dependent theory with three length scale parameters. The novelty of the current study is to consider the effects of porosity, GPLRC and MSGT... 

    Investigation of Dynamic Response of Buried Pipelines under Earthquake-Induced Landslide using Physical Model Tests

    , M.Sc. Thesis Sharif University of Technology Hadei, Sajjad (Author) ; Jafarzadeh, Fardin (Supervisor)
    Abstract
    The purpose of this dissertation is investigation of dynamic behavior of buried pipelines in slopes in landslide. For this purpose four physical models were made on shaking table of Sharif University of Technology. In each of the models some pipes were buried in slope. In these models the pipes were placed in different angles regarding to slope direction. Simulation laws suggested by Iai (1989) were used in these models. Babolsar sand was used for modeling the slopes. Aluminium pipes with outside diameter of 16 millimeters and thickness of 1 millimeter were implemented to model steel pipelines. In this investigation simple supports were used at the end of the pipes, considering the... 

    Failure Modeling of Reinforced Concrete Structures Using Plastic–Damage Models

    , M.Sc. Thesis Sharif University of Technology Hajibabaee, Meghdad (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    The modeling of mechanical behavior of Reinforced concrete Structures has been an important issue in civil engineering. In this thesis, an approach to the numerical modeling of different parts of these structures such as concrete and steel bars was presented. The model is based on damage and plasticity in porous materials. The behavior of steel materials was modeled through Von-Misses plasticity model while the coupling of the Gurson plasticity and a rate dependent damage model based on elastic strains were used for modeling the behavior of concrete materials. The effect of interaction between concrete and steel bar in RC members was considered through an experimental relation in which the... 

    Congestion effect on maximum dynamic stresses of bridges

    , Article Structural Engineering and Mechanics ; Volume 55, Issue 1 , 2015 , Pages 111-135 ; 12254568 (ISSN) Samanipour, K ; Vafaia, H ; Sharif University of Technology
    Techno Press  2015
    Abstract
    Bridge behavior under passing traffic loads has been studied for the past 50 years. This paper presents how to model congestion on bridges and how the maximum dynamic stress of bridges change during the passing of moving vehicles. Most current research is based on mid-span dynamic effects due to traffic load and most bridge codes define a factor called the dynamic load allowance (DLA), which is applied to the maximum static moment under static loading. This paper presents an algorithm to solve the governing equation of the bridge as well as the equations of motions of two real European trucks with different speeds, simultaneously. It will be shown, considering congestion in eight case... 

    Optimum Design Of Wave Mitigating Multi phase FGMs

    , M.Sc. Thesis Sharif University of Technology Zanjirzani, Hadi (Author) ; Tvakkoli, Roohollah (Supervisor)
    Abstract
    Functionally graded materials (FGMs) are categorized in a branch of composite materials in which the local volume fraction of contributing phases are not fixed throughout the spatial domain, but vary gradually as a function of position. This spatial variation leads to the gradual variation of physical and mechanical properties inside the materials. It provides us the opportunity of designing multiple purpose materials by the variation of local volume fractions according to our goal. The optimal distribution of local volume fractions is a function of the spatial domain geometry and loading conditions, and in general situations, due to the complexity of the problem, it is not possible to... 

    Investigation of Moving Subway Train Vibrational Effect on Surface Structures (Case Study:Tabriz Line 1 Metro)

    , M.Sc. Thesis Sharif University of Technology Tane Gonbadi, Bahram (Author) ; Sadaghiani, Mohammad Hossein (Supervisor)
    Abstract
    Ground surface vibration produced by underground running trains is a known impact of rail traffic and has been widely considered in recent years. This vibration can vary in the range of almost 2–200 Hz on the ground surface or in tunnels. In other words, Tunneling in urban areas always has hazards. One of the most important hazards is propagated vibrations due to underground moving trains on surface structures. Purpose of this study is the investigation of moving subway train vibrational effect in line number one of Tabriz metro near station 11. 3D numerical finite element model (ABAQUS) is used in this study. Study of dynamics of a moving train can be considered in three models:... 

    Physical Modeling of Buried Pipelines Response due to Earthquake-Induced Landslide

    , M.Sc. Thesis Sharif University of Technology Sehizadeh, Mahdi (Author) ; Jafarzadeh, Fardin (Supervisor)
    Abstract
    In this dissertation, the response of buried pipelines in slopes which have become unstable during earthquake induced landslides is investigated. The Sharif University of Technology shaking table was used for modeling this phenomenon.Three tests were performed so that in the first and second ones, three pipes were placed in different positions due to slope and the supports were elastic cylinders. In third test, there were four pipes with simple supports at the test-box walls.The pipes in every test were buried in the depth of 11 centimeters and they were all made of aluminum with the outside diameter of 16 millimeters and thickness of 1 millimeter. Also, they were all in the bending mode due... 

    Effects of Soil-Pile-Structure Interaction on the Seismic Response of a Bridges

    , M.Sc. Thesis Sharif University of Technology Tamaddoni, Nima (Author) ; Ahmadi, Mohammad Mahdi (Supervisor)
    Abstract
    A large number of structures subjected to the seismic loading have been damaged or have experienced failure in different parts such as the pile structure or even in the entire structure due to unanticipated effects of the soil-pile-structure interaction.The complexity of problems regarding the soil-pile-structure interaction is an influencing factor in prediction of the behavior of structure during the earthquakes. In this study, the effect of the interaction on the dynamic response of bridges was investigated using the finite element software ABAQUS. The primary purpose of this study, as previously described, is to study the effects of the soil-structure interaction on a bridge located on a... 

    Three Dimensional Dynamic Response of Buried Pipielines Due to Earthquake Induced Landslides by Numerical Modeling

    , M.Sc. Thesis Sharif University of Technology Sahragard Jouneghani, Faranak (Author) ; Jafarzadeh, Fardin (Supervisor)
    Abstract
    The purpose of this research is to study the effect of using expanded polystyrene (EPS) Geofoam to retrofit buried pipelines in slopes subjected to landslide due to earthquakes.For this purpose, several 3D numerical models were built with ABAQUS/CAE based on physical model tests conducted on shaking table device at Sharif University of Technology by previous research groups. Two parts are considered in this study. in the first part, three tests were simulated. Displacements, acceleration time histories and strains of pipes were compared to the tests results and the effect od EPS block on each pipe pesponse was observed. In the second part, effect of two factors on response of buried pipes...