Search for: cyclic-loads
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    Effect of cyclic loading on the temporomandibular joint

    , Article Lecture Notes in Engineering and Computer Science ; Volume 1 , 2014 , Pages 655-658 ; ISSN: 20780958 ; ISBN: 9789881925275 Muhandiram, J ; Wang, B ; Chizari, M ; Sharif University of Technology
    This research is aiming to investigate the mechanical behaviour of the temporomandibular joint (TMJ), in response to kinematics/cyclical loading caused through actions of speech and mastication. A set of in-vitro experimental tests has been performed in three different groups on a fresh sheep jaw bone to examine the hypothesis of the study. No failure was monitored during the cyclical test. The study was concluded that the amount of loading is effective on the displacement of the TMJ  

    Evaluation of variable permeability model in simulation of seismic behavior of uniform level and gently sloping sand layers

    , Article Earth Sciences Research Journal ; Volume 24, Issue 3 , 2020 , Pages 328-336 Ghassemi, A ; Seyfi, S ; Shahir, H ; Sharif University of Technology
    Universidad Nacional de Colombia  2020
    In this study, a fully coupled dynamic finite element model was employed for numerical simulation of the response of level to gently sloping saturated sand layers subjected to cyclic loading. This model utilized a critical state two-surface-plasticity constitutive model to simulate the cyclic behavior of sandy soil. Moreover, a recently proposed variable permeability function was implemented in the numerical model to reflect the effects of soil permeability variations during the liquefaction phenomenon. The numerical model was validated by simulating a number of well-documented geotechnical centrifuge tests with different relative density of sand, base acceleration time history, and surface... 

    Cyclic behaviour of interior reinforced concrete beam-column connection with self-consolidating concrete

    , Article Structural Concrete ; Volume 17, Issue 4 , 2016 , Pages 618-629 ; 14644177 (ISSN) Salehi Mobin, J ; Kazemi, M. T ; Attari, N. K. A ; Sharif University of Technology
    A significant amount of research on self-consolidating concrete (SCC) technology has been devoted to evaluating the suitability of the material for its use in structural applications. However, more research is required to confirm the adequacy of SCC structural members for resisting gravity and seismic loads. This study focuses on the experimental investigation of the seismic performance of interior reinforced concrete beam-column connections with SCC. Four beam-column connection specimens, three with SCC and one with normally vibrated concrete (NC), were designed for this experimental study. Factors such as concrete type (SCC or NC) and axial load ratio (0, 7.5 and 15 % of column section... 

    Mechanisms of fatigue damage in foam core sandwich composites with unsymmetrical carbon/glass face sheets

    , Article Journal of Reinforced Plastics and Composites ; Volume 26, Issue 17 , 2007 , Pages 1831-1842 ; 07316844 (ISSN) Zabihpoor, M ; Adibnazari, S ; Moslemian, R ; Abedian, A ; Sharif University of Technology
    This paper attempts to describe the fatigue response of a foam the core sandwich composite with unsymmetrical carbon/glass face sheets under tension-tension cyclic loading. The laminate is a critical element of the structure of a light full composite airplane which was determined through the stress analyses for numerous load cases. The face sheets, over a PVC foam the core, consist of two similar woven E-glass fibers following unidirectional carbon fibers with epoxy resin. Extensive fatigue data were generated for the S-N diagram of this laminate. Based on the static FEM analyses, two designs for the configuration of foam to solid laminate bonding zone have been investigated. Hence, the... 

    Numerical simulation of ductile crack growth under cyclic and dynamic loading with a damage–viscoplasticity model

    , Article Engineering Fracture Mechanics ; Volume 99 , February , 2013 , PP. 169–190 Khoei, A. R. (Amir Reza) ; Eghbalian, M ; Azadi, H ; Saffar, H ; Sharif University of Technology
    In this paper, the crack propagation in ductile materials is simulated under cyclic and dynamic loading. The adaptive finite element method is used to model the discontinuity due to crack propagation. The ductile fracture assumptions and continuum damage mechanics are utilized to model the material rupture behavior. Moreover both the rate-independent and rate-dependent constitutive equations are elaborated and the crack closure effect and combined hardening model are discussed in addition to some aspects of finite element implementation. Finally, a comparison is performed between the numerical simulation results and those of experiments to illustrate the robustness of proposed computational... 

    VM link element for consideration of shear-flexural interaction

    , Article 10th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2010, Bangkok, 3 August 2006 through 5 August 2006 ; Volume 2 , 2006 , Pages 149-154 Erfani, S ; Kazemi, M. T ; Sharif University of Technology
    A mixed shear-flexural beam element, which is called VM link element, is introduced. Dissimilar multi-surfaces in the shear-flexural space and non zero off diagonal components in flexibility matrixes are used for more realistic modeling of inelastic shear-flexural interaction. For preventing of intersecting among the yield surfaces, a new non-associated flow rule and a new kinematic hardening rule are developed. Capability of this element is examined for shear links used in eccentrically braced frames analysis for cyclic loading. It is shown that, the proposed link element is in a good agreement with the existing test results  

    Experimental/numerical evaluation of steel trapezoidal corrugated infill panels with an opening

    , Article Applied Sciences (Switzerland) ; Volume 11, Issue 7 , 2021 ; 20763417 (ISSN) Yaseri Gilvaee, M ; Mofid, M ; Sharif University of Technology
    MDPI AG  2021
    This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular opening, while the other one had two rectangular openings. In addition, the percentage of opening in both specimens was 18%. The initial stiffness, ultimate strength, ductility ratio and energy dissipation capacity of the two tested specimens are compared to a specimen without opening. The experimental results indicate that the existence of an opening has the greatest effect on the initial stiffness of the... 

    Application of frictional sliding fuse in infilled frames, fuse adjustment and influencing parameters

    , Article Structural Engineering and Mechanics ; Volume 36, Issue 6 , 2010 , Pages 715-727 ; 12254568 (ISSN) Mohammadi Gh, M ; Akrami, V ; Sharif University of Technology
    An experimental investigation is conducted here to study the effects of applying frictional sliding fuses (FSF) in concrete infilled steel frames. Firstly, the influences of some parameters on the behavior of the sliding fuse are studied: Methods of adjusting the FSF for a certain sliding strength are explained and influences of time duration, welding and corrosion are investigated as well. Based on the results, time duration does not significantly affect the FSF, however influences of welding and corrosion of the constitutive plates are substantial. Then, the results of testing two 1/3 scale single-storey single-bay concrete infilled steel frames having FSF are presented. The specimens were... 

    Strength parameters of asphalt concrete used in core zone of earth dams

    , Article Proceedings of the 17th International Conference on Soil Mechanics and Geotechnical Engineering: The Academia and Practice of Geotechnical Engineering ; Volume 2 , 2009 , Pages 1558-1561 ; 9781607500315 (ISBN) Jafarzadeh, F ; Yousefpour, N ; Sharif University of Technology
    Strength parameters of asphalt concrete used in earth fill dams' core were studied by conducting cyclic and monotonic triaxial tests on asphalt concrete samples. Results obtained from more than 120 cyclic tests showed that asphalt concrete behaves properly under cyclic loading and specimens stay intact after applying 5000 cycles. Results of monotonic and post-cyclic loading proved that strength parameters of asphalt concrete samples does not change significantly after being subjected to seismic loads. © 2009 IOS Press  

    Experimental investigation on the behavior of corrugated steel shear wall subjected to the different angle of trapezoidal plate

    , Article Structural Design of Tall and Special Buildings ; Volume 26, Issue 17 , 2017 ; 15417794 (ISSN) Hosseinzadeh, L ; Emami, F ; Mofid, M ; Sharif University of Technology
    Studies on corrugated steel shear walls (CSSWs) generally indicate noticeable increase of energy absorption, as well as increasing shear buckling capacity of corrugated plates being more likely rather than the flat plates. In this paper, the effect of variation in the angle of trapezoidal plate on the behavior of CSSWs has extensively been investigated. Three specimens of CSSW with 1 story and single bay in half scale are tested under cyclic load. The observations of experiment do indicate that stress concentration has been increased in the corner of subpanels, by increasing of the corrugation angle. Development of the tensile field and wall yield and damage depends on the geometry of the... 

    Relaxation of hardening in asphalt concrete under cyclic compression loading

    , Article Journal of Materials in Civil Engineering ; Volume 29, Issue 5 , 2017 ; 08991561 (ISSN) Jahangiri, B ; Karimi, M. M ; Tabatabaee, N ; Sharif University of Technology
    American Society of Civil Engineers (ASCE)  2017
    The present experimental study investigated the behavior of hot-mix asphalt (HMA) under repetitive creep and recovery loading. Cylindrical samples of HMA were subjected to trapezoidal and haversine loading followed by unloading. Different amounts of unloading (stress reduction) and relaxation periods (rest periods in complete unloading) were tested. The measured vertical deformation was decomposed into viscoelastic and viscoplastic components. It was observed for cyclic loading that an increase in unloading and/or relaxation period increased the recovery of viscoelastic strain, which in turn increased the accumulated viscoplastic strain in subsequent loading cycles. It appears that... 

    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
    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.... 

    Micro-structural aspects of fatigue crack propagation in atomistic-scale via the molecular dynamics analysis

    , Article Engineering Fracture Mechanics ; Volume 226 , 2020 Yasbolaghi, R ; Khoei, A. R ; Sharif University of Technology
    Elsevier Ltd  2020
    In this paper, the fatigue crack propagation is modeled using the Molecular Dynamics (MD) analysis based on the Embedded Atom Method (EAM). The crack growth simulation is performed for the single-crystal and poly-crystalline specimens subjected to cyclic loading/unloading conditions, and the crack growth rate is investigated at the atomistic level. The MD simulations are carried out under different model parameters, including the load pattern, maximum applied strain, temperature, loading frequency, and percentage of defects by employing more than 4000 molecular dynamics analyses to study the sensitivity of crack propagation process to the simulation parameters. The threshold values of... 

    Analytical study of special girder moment frames using a mixed shear-flexural link element

    , Article Canadian Journal of Civil Engineering ; Volume 34, Issue 9 , 2007 , Pages 1119-1130 ; 03151468 (ISSN) Kazemi, M. T ; Erfani, S ; Sharif University of Technology
    The present paper introduces a mixed shear-flexural (VM) link element that is capable of modelling shear yielding, flexural yielding, and their interaction under monotonic and cyclic loadings. The inelastic deformations are modelled using the multisurfaces approach with dissimilar yield surfaces and a stiffness matrix with nonzero off-diagonal components in shear-flexural space. A new kinematic hardening and new non-associated flow rules are employed. A special girder, which has an open web in the middle, is introduced and modelled using the developed VM link element. It is shown that the results of analyses using the VM link element are in good agreement with those from a finite element... 

    Evaluation of plasticity-based concrete constitutive models under monotonic and cyclic loadings

    , Article Structural Design of Tall and Special Buildings ; 2021 ; 15417794 (ISSN) Gharavi, A ; Asgarpoor, M ; Epackachi, S ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    This paper evaluates the applicability of several concrete models to simulate the behavior of concrete elements under monotonic and cyclic loadings. Several robust constitutive models based on the combination of plasticity and continuum damage or plasticity and smeared crack approach are selected. The behavior of one concrete element is evaluated under different uniaxial compression, uniaxial tension, biaxial compression, biaxial tension, biaxial compression–tension, and triaxial compression loads. Then, the applicability of the concrete models is investigated for two flexural beams under cyclic loading. Five concrete models available in the versatile finite element-based software LS-DYNA... 

    Study of microstructural growth under cyclic martensite phase transition in shape memory alloys; A molecular dynamics approach

    , Article Journal of Intelligent Material Systems and Structures ; 2021 ; 1045389X (ISSN) Moravej, S. A ; Taghibakhshi, A ; Nejat Pishkenari, H ; Arghavani, J ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Shape memory alloys are referred to as a group of alloys that can retrieve the permanent deformation and strain applied to them and eventually return to their original form. So far, various studies have been done to determine the behavior of these alloys under cyclic loading. Most of the studies have mainly been conducted by using the foundations of Continuum Mechanics in order to examine the properties of memory alloys. In this study, instead of using the Continuum Mechanics, a Molecular Dynamics simulation method using Lennard-Jones potential is utilized. The changes in the behavior and properties of memory alloy under cyclic loading are being examined. First, the functional form... 

    Numerical Modeling of Rocking Of Shallow Foundations Subjected to Slow Cyclic Loading with Consideration of Soil-Structure Interaction

    , M.Sc. Thesis Sharif University of Technology Fathi, Aria (Author) ; Haeri, Mohsen (Supervisor)
    Foundation is the lowest load-bearing part of a structure and a part of underneath soil that is affected by the structure load. In fact, foundation transfers the loads from the superstructure to the substructure, preventing excessive settlement of soil or stresses exceeding soil bearing capacity. Indeed, almost all structures are placed on the ground, therefore the effects of soil and structure on each other, which is known as Soil Structure Interaction (SSI), is considered as a key factor in many important and engineered structures. In contrast to structures on a rigid footing, a flexible foundation may show stiffness degradation along with an increase of damping and natural period of the... 

    A plasticity-based constitutive model for the behavior of soil-structure interfaces under cyclic loading

    , Article Transportation Geotechnics ; Volume 14 , 2018 , Pages 41-51 ; 22143912 (ISSN) Hosseinali, M ; Toufigh, V ; Sharif University of Technology
    Elsevier Ltd  2018
    In this study, a new plasticity-based constitutive model is proposed for the behavior of soil-structure interfaces under monotonic and cyclic loadings. The features of the interface including the strain-softening behavior, phase transformation, steady-state, and dilatancy behavior were described by the proposed model with satisfactory accuracy. The proposed model does not require additional concepts such as damage or disturbance, and the model parameters can be obtained easily using straight-forward analyses of the results obtained from constant normal stress tests. Moreover, the results of the proposed model showed its capability in predicting the experimental results obtained from various... 

    Nonlinear seismic behavior of RC frames with RC braces

    , Article Asian Journal of Civil Engineering ; Volume 9, Issue 6 , 2008 , Pages 577-592 ; 15630854 (ISSN) Khaloo, A. R ; Mohseni, M. M ; Sharif University of Technology
    Braced frames, besides other structural systems, such as moment resisting frames or shear walls, have been an effective and valuable method to enhance structures against lateral loads. In wind or seismic excitations, inclined elements react as truss web elements which would bear compression or tension stresses. This axial reaction results in less moments and therefore smaller sizes in beam and column sections with respect to members in similar moment resisting frame. However, low tensile strength of concrete material, made it a challenge to use in inclined members. In practice, there have been various methods to consider this defect such as disengagement of brace elements in tension or... 

    Buckling of the composite cracked cylindrical shells subjected to axial load

    , Article 2003 ASME International Mechanical Engineering Congress, Washington, DC, 15 November 2003 through 21 November 2003 ; Volume 470 , 2003 , Pages 87-93 ; 0277027X (ISSN) Vaziri, A ; Nayeb Hashemi, H ; Estekanchi, H. E ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2003
    Cylindrical shells constitute the main structural components in pressure vessels and pipelines. Cylindrical shells made of fiber-reinforced composites are now being considered in the design of many components due to their high specific strength and stiffness. Buckling is one of the main failure considerations, when designing the cylindrical shells. The buckling behavior of the composite cylindrical shells can severely be compromised by introducing defect in the structure, due to high stress field generated around these defects. Defects could be generated during service due to cyclic loading or during manufacturing. A reliable operation of these structures require to understand the effects of...