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  • دکتری (1384)

    مهندسی سازه

    دانشگاه صنعتی شریف، تهران، ایران

  • کارشناسی‌ارشد (1379)

    مهندسی سازه

    دانشگاه صنعتی شریف، تهران، ایران

  • کارشناسی (1377)

    مهندسی عمران

    دانشگاه صنعتی شریف، تهران، ایران

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    رزومه

    Uniaxial and triaxial failure strength of fiber reinforced EPS concrete

    Amirali Babavalian, Amir Hossein Ranjbaran, Sharif Shahbeyk
    Journal PapersConstruction and Building Materials , Volume 247 , 2020 June 30, {Pages 118617 }

    Abstract

    EPS concrete is a relatively new lightweight building material with a combination of favorable properties. Available experimental results have shown that, for low volume contents of EPS, the presence of lightweight beads reduces strength more than density. This fact has led a few researchers to try to reinforce EPS concrete with fibers to partially compensate the strength loss. In this regard, the current study examines the simultaneous effects of EPS beads and polypropylenee fibers on tensile splitting, uniaxial compressive, and confined behavior of concrete by running 160 tests on cylindrical specimens. The results of different tests consistently showed that the strengthening effect of fibers is noticeably improved at higher EPS volume co

    Experimental and microstructural study of the compressive strength of concrete samples containing low volumes of expanded polystyrene beads

    Mohammad Bakhshi, Sharif Shahbeyk
    Journal PapersStructural Concrete , Volume 20 , Issue 4, 2019 August , {Pages 1379-1390 }

    Abstract

    The partial replacement of aggregates with expanded polystyrene (EPS) beads is a common technique to produce lightweight concretes. Much research have been already conducted on the compressive strength of EPS concretes containing high volumes of EPS beads. In the current study, however, specimens with low EPS volume contents are also examined. The results show that all the strength versus EPS volume content graphs initiate with a nearly plateau region. The length of this plateau region is found to be an increasing function of W/C ratio. It is also observed that the replacement of redundant water with the EPS beads initially improves strength but the trend is reversed beyond a critical volume content. Finally, the new empirical findings are

    Review of Size Effects during Micropillar Compression Test: Experiments and Atomistic Simulations

    Sharif Shahbeyk, George Z Voyiadjis, Vahid Habibi, Sarah Hashemi Astaneh, Mohammadreza Yaghoobi
    Journal Papers , Volume 9 , Issue 11, 2019 November , {Pages 591 }

    Abstract

    The micropillar compression test is a novel experiment to study the mechanical properties of materials at small length scales of micro and nano. The results of the micropillar compression experiments show that the strength of the material depends on the pillar diameter, which is commonly termed as size effects. In the current work, first, the experimental observations and theoretical models of size effects during micropillar compression tests are reviewed in the case of crystalline metals. In the next step, the recent computer simulations using molecular dynamics are reviewed as a powerful tool to investigate the micropillar compression experiment and its governing mechanisms of size effects. View Full-Text

    Seismic Behavior of Steel Frames Equipped with Comb-Teeth Metallic Yielding Dampers

    S Garivani, AA Aghakouchak, S Shahbeyk
    Journal PapersInternational Journal of Steel Structures , 2018 January , {Pages 14-Jan }

    Abstract

    Comb-teeth damper (CTD), is a new type of metallic yielding damper, which is made of steel plates and includes a number of teeth that dissipate energy through in-plane flexural yielding. The behavior of individual samples of CTD have been previously studied numerically and experimentally and it has been shown that this damper has excellent energy dissipating capacity and large ductility ratio. In this paper, application of this type of damper to steel frames is studied. Sample steel frames are constructed and equipped with CTDs and tested under cyclic loading. The results show that these dampers can serve their intended duties and dissipate considerable amount of energy. Numerical modelling of the frames confirms the experimental results an

    A physically consistent stress-strain model for actively confined concrete

    Sharif Shahbeyk, Mahshid Z Moghaddam, Mohammad Safarnejad
    Journal PapersComputers and Concrete , Volume 20 , Issue 1, 2017 July 1, {Pages 85-97 }

    Abstract

    With a special attention to the different stages of a typical loading path travelled in a fluid confined concrete test, this paper introduces a physically consistent model for the stress-strain curve of actively confined normal-strength concrete in the axial direction. The model comprises of the five elements of:(1) a criterion for the peak or failure strength,(2) an equation for the peak strain,(3) a backbone hydrostatic curve,(4) a transient hardening curve linking the point of departure from the hydrostatic curve to the failure point, and finally (5) a set of formulas for the post-peak region. Alongside, relevant details and shortcomings of existing models will be discussed in each part. Finally, the accuracy and efficiency of the propos

    A comparative study of the yield criteria applicable to replicated foams

    Ehsan Haghighi, Sharif Shahbeyk
    Journal PapersMechanics of Advanced Materials and Structures , Volume 24 , Issue 7, 2017 May 19, {Pages 535-544 }

    Abstract

    In this article, first some published evidence for yielding of aluminum and polymeric replicated foams and a numerical study on regular porous structures are revisited in which a kind of twist in the shape of yield surface along the hydrostatic axis was reported. Next, motivated by this observation, some existing appropriate yield functions and a new extended generalized failure criterion capable of capturing this effect are presented. Finally, using the experimentally measured yield clouds of aluminum replicated foams from the literature, the efficiency, inherent features, and limitations of these criteria are thoroughly assessed, compared, and discussed.

    Numerical and experimental study of comb-teeth metallic yielding dampers

    S Garivani, AA Aghakouchak, S Shahbeyk
    Journal PapersInternational Journal of Steel Structures , Volume 16 , Issue 1, 2016 March 1, {Pages 177-196 }

    Abstract

    In this paper, a new type of metallic yielding damper called comb-teeth damper, CTD, is introduced. CTD is made of steel plates and includes a number of teeth that dissipate energy through in-plane flexural yielding. An optimum geometry of teeth is suggested, which assures uniform distribution of stress along them and prevents strain localization. Finite element modeling is used to verify the design of proposed damper and to study nonlinear behavior of the damper subjected to monotonic as well as cyclic loading. Three full scale specimens have also been made and tested under cyclic loading. In order to restrict out-ofplane buckling of damper teeth, a special clamp has been designed. A numerical study has elaborated the effect

    A Rigid Body-Spring Model with FE-Based Kinematic Assumptions for the Elastic Analysis of Continua

    M Safarnejad, S Shahbeyk
    Journal Papersسّردم نارمع یسدنهم , Volume 16 , Issue 5, 2016 November , {Pages 90 }

    Abstract

    Rigid Body-Spring Models (RBSMs) are a kind of discrete models which are developed mainly for the simulation of quasi-brittle materials ranging from ceramic, concrete, and masonry, to rock and soil. In this approach, material domain is discretized to a set of rigid cells interconnected through a set of translational and rotational springs located at cell interfaces. These cells are constructed over a set of points (seeds) distributed regularly or randomly over the domain. When it comes to heterogeneous materials, the seeds may be located in accord to the geometry and distribution of inclusions. For two-dimensional problems, each rigid cell has normally two translational and one rotational degrees of freedom (DOFs). The springs may be distri

    EXTENDING LATTICE DISCRETE PARTICLE MODEL OF CONCRETE FOR NON-CIRCULAR AGGREGATES

    M KAMZA, M SAFARNEJAD, S SHAHBEYK
    Journal Papers , Volume 35 , Issue 1, 2016 January 1, {Pages 25-Nov }

    Abstract

    In this paper, Lattice-Discrete Particle Model (LDPM) of concrete has been extended in 2-D to account for the effect of non-circular aggregates. To this end, the flexible equation of super-ellipse is employed for generating aggregates in order to add the simulation possibility of a greater spectrum of aggregate samples in 2-D to lattice-Discrete particle Model.

    EXPERIMENTAL AND ANALYTICAL STUDY OF THE CYCLIC PERFORMANCE OF SPECIAL CONCENTRIC BRACED FRAMES

    A FOOLADVAND, A AGHAKOUCHAK, S SHAHBEYK
    Journal Papers , Volume 312 , Issue 41, 2016 January 1, {Pages 51-60 }

    Abstract

    The special concentrically braced frame (SCBF) is a common type of steel structural system for resisting lateral loading. This type of system provides the required stiffness and strength at relatively low cost. Design codes, based on past research, have recommended some details for connections and braces, in order to ensure sufficient ductility and energy dissipation capacity in this system for their application in seismic design. In this paper, the behavior of four SCBF specimens with different details of connections is studied using experimental and numerical models. They are single story single bay sub-assemblages of frames with a single brace that are subjected to lateral cyclic loads. In the first specimen, a 2tp straight line clearanc

    A systematic approach for the modeling of replicated foams

    Mehrad Mousavi Rahimi, Sharif Shahbeyk
    Journal PapersAdvanced Engineering Materials , Volume 17 , Issue 6, 2015 June , {Pages 846-855 }

    Abstract

    This paper proposes a numerical framework for realistic simulation of replicated foams. The method is inspired by the actual processes used in the manufacturing of this class of cellular materials. Accordingly, an assembly of space‐holders is generated first, then the physical process of cold isostatic pressing is simulated and, finally, the structure resulting from the leaching process is modeled using a voxel‐like finite element model and an efficient inverting algorithm. A simple yet effective solution for the simulation of the influence of infiltration pressure on the microstructure of foam is also suggested. Next, the numerical approach is verified using the experimental results of a set of replicated aluminum foams whose preforms

    The Chaboche hardening rule: A re-evaluation of calibration procedures and a modified rule with an evolving material parameter

    Honeyeh Ramezansefat, Sharif Shahbeyk
    Journal PapersMechanics Research Communications , Volume 69 , 2015 October 1, {Pages 150-158 }

    Abstract

    This study first re-examines key existing calibration procedures for the Chaboche decomposed nonlinear kinematic hardening rule. Special attention has been paid to the extent to which the predictions of calibrated models represent the physics of phenomena observed in strain- and stress-controlled cyclic tests. It has been shown and discussed that newer methods suffer from some weaknesses and may yield nonphysical results. Second, with the aim of improving the accuracy of its ratcheting strain predictions in unsymmetric stress-controlled tests, a modified calibration procedure and a new Chaboche hardening rule with an evolving material parameter is introduced. The former improves the accuracy of predicted ratcheting strains at the initial cy

    Numerical implementation and calibration of microplane model for closed-cell metal foams with spherical cellular structure

    Amir Souri, Sharif Shahbeyk
    Journal PapersModares Mechanical Engineering , Volume 14 , Issue 10, 2015 January 15, {Pages 121-128 }

    Abstract

    Metal foams as a new class of materials with interesting properties such as high stiffness and strength to density ratios, capacity to absorb impact energy, and reproducibility, are rapidly growing their share in engineering applications such as aerospace, automotive industry, lightweight structures, and energy absorbers. Different numerical approaches have been already developed for the simulation of this class of materials from which the two-scale microplane model has been focused in this research. First a simple algorithm has been proposed for the numerical implementation of microplane model to simulate the mechanical behavior of closed-cell metal foams. The structure of foam is assumed to be an assembly of firmly bonded spherical shells

    An efficient energy dissipating device called comb teeth damper

    Sadegh Garivani, Ali Akbar Aghakouchak, SH Shahbeyk
    Journal PapersProceedings of the 2nd European Conference on Earthquake Engineering and Seismology, Istanbul-Turkey , 2014 January , {Pages }

    Abstract

    Experimental studies have confirmed very stable hysteretic behavior of CTDs under cyclic loading with large displacement amplitudes. For example, a specimen was loaded under twenty fully reversed cycles at amplitude of 40 mm and even after these cycles, hysteretic curves were quite stable and thus displacement amplitude was increased to 60 mm. It should be noted that 40 and 60 mm in amplitude respectively correspond to more than 20 and 30 times the yield displacement of outer fiber of links.After numerical and experimental investigation of the behavior of CTD specimens, the behavior of three simple steel frames equipped with such dampers is studied under cyclic loading. In this regard, CTDs are installed between beams and Chevron bracing. T

    Lattice discrete particle modeling of compressive failure in hollow concrete blocks

    Fatemeh Javidan, Sharif Shahbeyk, Mohammad Safarnejad
    Journal PapersComputers and Concrete , Volume 13 , Issue 4, 2014 April 1, {Pages 437-456 }

    Abstract

    This work incorporates newly introduced Lattice Discrete Particle Model (LDPM) to assess the failure mechanism and strength of hollow concrete blocks. Alongside, a method for the graphical representation of cracked surfaces in the LDPM is outlined. A slightly modified calibration procedure is also suggested and used to estimate required model parameters for a tested concrete sample. Next, the model is verified for a compressively loaded hollow block made of the very same concrete. Finally, four geometries commonly used in the production of hollow concrete blocks are selected, numerically simulated, and their failure properties are explored under concentric and eccentric compressions.

    A Numerical Study on the Uniaxial Mechanical Properties of Metal Foams with Spherical Cellular Structure.

    A Souri, S Shahbeyk, D Rahiminejad
    Journal PapersModares Journal of Civil Engineering , Volume 14 , Issue 2, 2014 September 1, {Pages }

    Abstract

    Metal foams as a new class of materials with interesting properties such as high stiffness and strength to density ratios, capacity to absorb impact energy, and reproducibility, are rapidly growing their share in advanced materials market. However, due to their porous microstructure, experimental investigations of their properties are not trivial and normally need rigorous procedures and high end equipments. Accordingly, there is a growing research interest towards the numerical modeling of their cellular structure in which the following three kinds of models have been commonly employed:(1) structures based on a unit cell or a building block,(2) random Voronoi diagrams, and (3) CAD data provided by X-ray micro-computed tomography. In the cu

    An efficient energy dissipating device called comb teeth damper

    Sadegh Garivani, Ali Akbar Aghakouchak, SH Shahbeyk
    Journal PapersProceedings of the 2nd European Conference on Earthquake Engineering and Seismology , 2014 January , {Pages }

    Abstract

    Experimental studies have confirmed very stable hysteretic behavior of CTDs under cyclic loading with large displacement amplitudes. For example, a specimen was loaded under twenty fully reversed cycles at amplitude of 40 mm and even after these cycles, hysteretic curves were quite stable and thus displacement amplitude was increased to 60 mm. It should be noted that 40 and 60 mm in amplitude respectively correspond to more than 20 and 30 times the yield displacement of outer fiber of links.After numerical and experimental investigation of the behavior of CTD specimens, the behavior of three simple steel frames equipped with such dampers is studied under cyclic loading. In this regard, CTDs are installed between beams and Chevron bracing. T

    Finite element simulation of ultra low cycle fatigue cracking in steel structures

    HR Amiri, AA Aghakouchak, S Shahbeyk, Michael D Engelhardt
    Journal PapersJournal of Constructional Steel Research , Volume 89 , 2013 October 1, {Pages 175-184 }

    Abstract

    This paper proposes a new method of simulating ductile fracture in steel structures under large amplitude cyclic straining experienced in earthquakes. The method is developed based on an existing micromechanical model originally proposed for predicting crack initiation in ultra-low cycle fatigue, ULCF. It involves a step-by-step simulation of material degradation within the framework of conventional nonlinear FEM. The method is validated through simulating fracture in a structural detail (column-to-base plate connection) for which several cyclic tests has been previously conducted. It is found that the method can successfully predict the cracking site, its propagation path, the number of cycles corresponding to crack initiation, and also fi

    Yield/failure criteria, constitutive models, and crashworthiness applications of metal foams

    SHARIF Shahbeyk
    Journal PapersMetal Foams: Fundamentals and Applications , 2013 January , {Pages 131-214 }

    Abstract

    HIS chapter is dedicated in its first section to the conventional plas-ticity modeling of metal foams. It begins with an introductory part discussing briefly the structure of the models and the definitions of their basic constituents; ie, the yield/failure criterion, hardening rule, hardening variables, flow rule, and consistency condition. It continues with a part fully devoted to the issue of failure in this class of materials. Two distinct physical and mathematical strategies toward the identification of yield/failure criteria are explored and examples are given. The success of both approaches relies on the accuracy of the data provided by experiments, or nowadays by analytical or numerical mesostructural analyses. The related important

    Shape optimization of hollow concrete blocks using the lattice discrete particle model,”

    Fatemeh Javidan, Mohammad Safarnejad, Sharif Shahbeyk
    Journal PapersIranica Journal of Energy & Environment-Geo-hazards and Civil Engineering , Volume 4 , Issue 3, 2013 July 1, {Pages 243-250 }

    Abstract

    Accepted in Revised Form: April 30, 2013) Abstract: Hollow concrete blocks are one of the widely used building elements of masonry structures in which they are normally loaded under combined action of shear and compression. Accordingly and due to their structural importance, the present study intends to numerically search for an optimum shape of such blocks. The optimality index is selected to be the ratio of block’s failure strength to its weight, a non-dimensional parameter, which needs to be maximized. The nonlinear analysis has been done using a homemade code written based on the recently developed Lattice Discrete Particle Model (LDPM) for the meso-scale simulation of concrete. This numerical approach accounts for the different aspec

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    دروس نیمسال جاری

    • كارشناسي ارشد
      مكانيك شكست ( واحد)
      دانشکده مهندسی عمران و محیط زیست، گروه مهندسي سازه

    دروس نیمسال قبل

    • كارشناسي ارشد
      تئوري پلاستيسيته ( واحد)
      دانشکده مهندسی عمران و محیط زیست، گروه مهندسي سازه
    • 1400
      بدرخاني حكم ابادي, مرتضي
      حل تحليلي ارتجاعي پانل هاي ساندويچي با هسته گسسته تحت خمش يك جهته
    • 1400
      صادقي, سروش
      داده ای یافت نشد
    • برنده مدال برنز المپیاد ریاضی کشوری (1372)

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