Search for: lateral-displacements
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    Arrangements of shear walls in control of lateral displacement of concrete frames

    , Article World Applied Sciences Journal ; Volume 17, Issue 10 , 2012 , Pages 1324-1330 ; 18184952 (ISSN) Shamsai, A ; Rahemi, L ; Rahmani, K ; Peroti, S ; Sharif University of Technology
    One of the major shortcomings of conventional and rather high-rise structures is increasing lateral displacements arising from lateral forces which finally make the entire project un-economical. In this research, effort has been made to investigate the effect of shear walls arrangements on the lateral displacement of the structure. Two types of structures including 16 and 32-storeys frameswith different arrangements of shear panels were examined. The findings indicate that compared to other frames, the performance of frame no. 1 in both types of structures was poor in controlling the overall displacement of structure. Furthermore, more number of shear panels are not necessarily effective in... 

    The contribution of the medial retinaculum and quadriceps muscles to patellar lateral stability - An in-vitro study

    , Article Knee ; Volume 11, Issue 2 , 2004 , Pages 89-94 ; 09680160 (ISSN) Farahmand, F ; Tahmasbi, M. N ; Amis, A ; Sharif University of Technology
    Patellofemoral joint stability is a result of the restraining effects of the quadriceps muscles, the retinacular structures, and engagement of the bones. The role and significance of these mechanisms in restraining patellar lateral displacement was investigated in this study by measuring the force needed to cause 5 mm lateral displacement (i.e. the mechanical stability, or 'stabilising force') of the patella. Six cadaver knees had 175 N quadriceps load distributed among three muscle groups. With a force ratio matching the muscles physiological cross sectional areas, no significant change occurred in the patellar stabilising force between 0 and 60°knee flexion, but a significant increase... 

    Assessment of the vertical stiffness of elastomeric bearing due to displacement and rotation

    , Article International Journal of Non-Linear Mechanics ; Volume 119 , 2020 Kazeminezhad, E ; Kazemi, M. T ; Mirhosseini, S. M ; Sharif University of Technology
    Elsevier Ltd  2020
    The vertical stiffness of elastomeric bearing is a dominant parameter of the base isolation design. Several empirical relations have been used to calculate the vertical stiffness of the elastomeric bearing systems, although, in certain conditions such as the presence of rotation, these relations are not accurate enough. In this paper, by using a nonlinear finite element program, the effect of rotation on the vertical stiffness investigated. It was observed that the vertical stiffness of the isolator could be increased or decreased depending on the amount of rotation and the value of lateral displacement limit. © 2019 Elsevier Ltd  

    A Survey on Conversion Coefficient of Relative Lateral Displacement of Linear Analysis to Real Relative Lateral Displacement of Structure

    , M.Sc. Thesis Sharif University of Technology Akhavan Sigari Yazd, Mohammad Hossein (Author) ; Khaloo, Ali Reza (Supervisor)
    In recent years, displacement is more considered in comparison with force in design of structures. For example in 2800 standard -3rd edition- it is stated that for the reason that real displacement of structure in linear analysis is not calculable; it is necessary to resonate the lateral displacement of elastic analysis with a coefficient which is related to behavior coefficient of structure. This displacement should be less than allowable limit that is noted in the code. In similar foreign codes importance factor is also noted beside behavior factor in calculation of real lateral displacement of structure. Evaluation of this coefficient for different structures, comparison with suggested... 

    Design, modeling and optimization of a novel two DOF polymeric electro-thermal micro-actuator

    , Article Applied Mechanics and Materials ; Vol. 307 , 2013 , pp. 112-116 ; ISSN: 16609336 ; ISBN: 9783037856598 Sheikhbahaie, R ; Alasty, A ; Salarieh, H ; Sharif University of Technology
    In this paper, design, simulation and optimization of a novel electrothermally-activated polymeric microactuator capable of generating combination of bidirectional lateral and rotational motions are presented. The composite structure of this actuator is consisted of a symmetric meandered shape silicon skeleton, a SU8 thermal expandable polymer and a thin film chrome layer heater. This actuator is controlled by applying appropriate voltages on its four terminals. With the purpose of dimension optimization, a numerical parametric study is executed. The modeled actuator which is 1560 ?m long, 156 ?m wide and 30 ?m thick, demonstrates a remarkable lateral displacement of 23 ?m at power... 

    Assessing the shear behavior of oriented rock joints under constant normal loading conditions

    , Article Geotechnical Special Publication ; February , 2014 , p. 553-562 Khosravi, A ; Khosravi, M ; Sadaghiani, M. H ; Meehan, C. L ; Amini, E ; Sharif University of Technology
    This paper presents results from a series of constant normal load direct shear tests on artificially created rock joints, in an attempt to quantify the effects of different factors that contribute to the shear strength along "ideal" rock joints. Particular focus is given to the effect of asperity orientation with respect to the direction of shearing. In many historical rock joint shear strength criteria, the effect of a joint's roughness on the joint shear strength is described based on analysis of only a single profile in the direction of shearing. More recent studies have observed that the distribution of sheared area on a joint surface during shear is significantly affected by the... 

    Fiber core size determination from power measurements in a fiber-to-fiber design

    , Article Microwave and Optical Technology Letters ; Volume 53, Issue 6 , 2011 , Pages 1225-1229 ; 08952477 (ISSN) Golnabi, H ; Sharif University of Technology
    Fiber core size determination from power transmission modulation for different fibers is reported.Three different fibers are tested and power variations of lateral displacement of the second fiber are obtained (lamp, red LED). From the averaged bandwidths of the response curves the core diameter of each fiber is determined. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1225-1229, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25967 Copyright  

    Prediction of lateral spreading displacement on gently sloping liquefiable ground

    , Article Geotechnical Frontiers 2017, 12 March 2017 through 15 March 2017 ; Issue GSP 281 , 2017 , Pages 267-276 ; 08950563 (ISSN) Ghasemi Fare, O ; Pak, A ; Geo-Institute (G-I) of the American Society of Civil Engineers; Industrial Fabrics Association International (IFAI) ; Sharif University of Technology
    American Society of Civil Engineers (ASCE)  2017
    A fully coupled numerical analysis using Biot's theory with u-p formulation considering variable permeability during liquefaction is used in this study to simulate liquefaction induced lateral spreading phenomenon. A centrifuge test performed on liquefiable soil at Rensselaer Polytechnic Institute is simulated using the developed model. The numerical results are in good agreement with experimental observations. A number of numerical simulations under different geometric, site-specific, and ground acceleration parameters have been carried out in the course of this study. Based on the statistical analysis conducted on the results of 31 different models, a new relation is proposed for... 

    Numerical investigation of the effects of geometric and seismic parameters on liquefaction-induced lateral spreading

    , Article Soil Dynamics and Earthquake Engineering ; Volume 89 , 2016 , Pages 233-247 ; 02677261 (ISSN) Ghasemi Fare, O ; Pak, A ; Sharif University of Technology
    Elsevier Ltd  2016
    The lateral movement of a liquefiable soil layer on gentle slopes is the most visible and devastating type of liquefaction-induced ground failure. Recent earthquakes have shown that this phenomenon causes severe damages to coastal structures, pier of the bridges and life-lines by exerting large lateral forces on the structures. In this paper coupled dynamic field equations of extended Biot's theory with u-p formulation are used for simulating the phenomenon and the soil behavior is modeled by a critical state two-surface plasticity model for sands. Furthermore, in this study variation of permeability coefficient during liquefaction is taken into account. The permeability coefficient is... 

    Numerical Simulation of Ground Displacement Induced by Lateral Spreading Phenomenon

    , M.Sc. Thesis Sharif University of Technology Ghasemifare, Omid (Author) ; Pak, Ali (Supervisor)
    The lateral movement of a liquefiable layer on gently slopes is the most visible and devastating type of liquefaction-induced ground failure. Occurrence of liquefaction in sloping ground causes large deformations on ground surface, which may lead to several meters in some cases. Recent earthquakes have shown that this phenomenon causes severe damages to coastal structures, piers of bridges and life-lines, by exerting large lateral forces. In this research, a fully coupled two-dimensional dynamic analysis has been used to simulate the lateral spreading phenomenon and to evaluate the magnitude of deformations occurred in liquefiable soils. The critical state bounding surface elastic-plastic... 

    Effects of using low yield point steel in steel plate shear walls

    , Article IES Journal Part A: Civil and Structural Engineering ; Vol. 7, Issue. 1 , 2014 , pp. 51-56 Jebelli, H ; Mofid, M ; Sharif University of Technology
    Steel plate shear walls are lateral load resisting systems, especially against earthquake excitation. They are constructed with or without stiffeners. Stiffened walls are more ductile than those without stiffeners. In this research a numerical study using finite element analysis via a finite element program is conducted. Nine thin steel plate shear wall models were considered in three groups of 5-storey, 10-storey and 15-storey walls. In each group different yield point steel for the infill plate was used. The yield points of infill plates were assumed to be 160, 200 and 240 MPa. The results showed that using low yield point (LYP) steel will increase energy dissipation of models by up to... 

    Nonlinear dynamic analysis of an axially loaded rotating Timoshenko beam with extensional condition included subjected to general type of force moving along the beam length

    , Article JVC/Journal of Vibration and Control ; Volume 19, Issue 16 , 2013 , Pages 2448-2458 ; 10775463 (ISSN) Mamandi, A ; Kargarnovin, M. H ; Sharif University of Technology
    In this paper the non-planar nonlinear dynamic responses of an axially loaded rotating Timoshenko beam subjected to a three-directional force traveling with a constant velocity is studied. On deriving the nonlinear coupled partial differential equations (PDEs) of motion the stretching effect of the beam's neutral axis due to the pinned-pinned ends' condition in conjunction with the von Karman strain-displacement relation are considered. The beam's nonlinear governing coupled PDEs of motion for the bending rotations of warped cross-section, longitudinal and lateral displacements are derived using Hamilton's principle. To obtain the dynamic responses of the beam, derived PDEs of motion are... 

    Investigation of in-orbit disturbing loads induced on spacecraft due to elastic deploying arm

    , Article International Journal of Structural Stability and Dynamics ; Volume 13, Issue 4 , 2013 ; 02194554 (ISSN) Ghaleh, P. B ; Malaek, S. M ; Sharif University of Technology
    The loads induced on the spacecraft orbiting the Earth by the deploying elastic arm are investigated. The coupled equations of motion of the arm with the vehicle orbital mechanics are used to describe the 3D dynamic behavior of the flexible-appendage and the related disturbing loads induced on the spacecraft. To this end, an equivalent dynamical system is derived for the arm by applying an attached Non-Newtonian Reference Frame which is subjected to the orbital motion and geocentric pointing maneuver of the spacecraft. With the help of the Assumed Modes Method, the behavior of the arm attached to the spacecraft in Keplerian orbits is studied. The results show that deploying the arm in some... 

    3D Dynamic analysis of a flexible deploying arm subjected to base angular motions

    , Article International Journal of Structural Stability and Dynamics ; Volume 13, Issue 2 , March , 2013 ; 02194554 (ISSN) Ghaleh, P. B ; Malaek, S. M ; Sharif University of Technology
    Problems related to the three-dimensional (3D) dynamics of the deploying flexible arms subjected to base angular motions are studied with simulated tip payloads and actual deployment trajectories. To facilitate the solution, an equivalent dynamical system is developed by introducing the inertial reaction forces on the arm, while the equations of motion are derived in the non-Newtonian reference frame attached to the arm. The dynamic behavior of the arm is investigated both by the finite element and assumed Modes methods for the purpose of verification. This study reveals that base angular motions lead to considerable couplings between the two lateral displacements and axial motions.... 

    Numerical investigation into the static behavior of stepped soil nail walls

    , Article Scientia Iranica ; Volume 25, Issue 1 , 2018 , Pages 140-151 ; 10263098 (ISSN) Ahmadi, M. M ; Borghei, A ; Sharif University of Technology
    Sharif University of Technology  2018
    This paper presents a numerical investigation into the static behavior of stepped soil nail walls constructed in dry sandy soils. The finite element method was used to study influence of wall geometry and soil parameters on behavior of the walls. We analyzed walls with heights of 10, 15, and 20 m. This study shows that the wall deformation and the nail tensile forces of the stepped soil nail wall are smaller than those of the typical soil nail wall. If properties of soils such as friction angle, cohesion, and elastic modulus decrease, more decrease in the wall lateral displacement and nail tensile forces of a stepped soil nail wall would occur. Therefore, stepped soil nail walls are more... 

    On the effect of ductility of confining material on concrete ductility

    , Article Proceedings of the 2009 Structures Congress - Don't Mess with Structural Engineers: Expanding Our Role, 30 April 2009 through 2 May 2009, Austin, TX ; 2009 , Pages 259-269 ; 9780784410318 (ISBN) Moghaddam, H. A ; Samadi, M ; Sharif University of Technology
    This paper presents the results of an experimental and analytical study on the improvements gained in the axial compressive behavior of confined concrete. Among several parameters affecting compressive ductility of confined concrete, including confinement mechanical volumetric ratio, shape and size effect, number of confinement layers, strength of plain concrete and ductility of confining material, the latter was found to play the most important role in determining the ultimate strain and post peak behavior of concrete. Axial compressive tests were performed on small-scale circular or square section concrete columns, which were retrofitted either by CFRP jacket or by two types of... 

    On the equivalent simple models of braced steel shear panels

    , Article Proceedings of the Institution of Civil Engineers: Structures and Buildings ; Volume 168, Issue 8 , August , 2015 , Pages 570-577 ; 09650911 (ISSN) Hamed, A. A ; Mofid, M ; Sharif University of Technology
    Thomas Telford Services Ltd  2015
    Through the combination of two types of seismic resisting systems including braced frames and steel shear walls, braced steel shear panel systems can be formed. This new lateral load-resisting system solves some of the defects of current special steel shear walls, such as imposing significant loads on boundary elements along with gravity load effects. Analysis and design of this new structural system underline the importance of having simple and precise finite-element models. To this aim, this paper presents two types of equivalent braced frames termed ‘overall equivalent brace’ and ‘equivalent mid-brace’. The equations of brace area, material strength and strain-hardening ratio are obtained... 

    Power modulation in axial and lateral fiber displacements in a fiber-to-fiber design

    , Article Optics and Lasers in Engineering ; Volume 48, Issue 10 , 2010 , Pages 987-993 ; 01438166 (ISSN) Golnabi, H ; Kargaran, A ; Heidari, F ; Sharif University of Technology
    In this study power transmission modulation for different fibers in a fiber-to-fiber design using two different light sources is reported. A fiber-to-fiber arrangement is used in which the source light is directly coupled to the first fiber and the second fiber delivers the light to a power meter. Arrangements with three sets of different type fibers are tested in this study and output powers are monitored with the white lamp or red LED as illumination light sources. Using this arrangement the variations of the power as a result of axial (Z-direction) and lateral (X- and Y-direction) displacements of the second fiber are monitored. Theoretical models are also used to evaluate the power... 

    Numerical assessment of new compound restrainer for seismic retrofit of bridges

    , Article Structure and Infrastructure Engineering ; 2017 , Pages 1-20 ; 15732479 (ISSN) Joghataie, A ; Pahlavan Yali, A ; Sharif University of Technology
    This paper studies through numerical simulation a practical compound restrainer to use for the improvement of seismic performance of bridges. A mechanical model has been introduced for the restrainer and a basic optimisation approach has been conducted to evaluate the performance of the restrainer to changes in the properties of its components. A real 2-span simply supported plate girder bridge has been selected for case study. Using a detailed three-dimensional model, several non-linear time history analyses were performed under seismic excitations in order to assess the performance of the bridge retrofitted by conventional restrainers including linear and non-linear viscous dampers on one... 

    Seismic behavior of pile-supported systems in unsaturated sand

    , Article Soil Dynamics and Earthquake Engineering ; Volume 112 , 2018 , Pages 162-173 ; 02677261 (ISSN) Ghayoomi, M ; Ghadirianniari, S ; Khosravi, A ; Mirshekari, M ; Sharif University of Technology
    The seismic behavior of pile-supported systems has been an active area of research over the past decades. However, focus has mostly been on evaluating the seismic response of structures embedded in either dry or fully saturated soil conditions. In this study, series of dynamic centrifuge tests were conducted to investigate the effects of soil's degree of saturation on the seismic behavior of pile-supported superstructures. The scaled physical model tests were carried out on two distinct pile-mass systems embedded in uniform sand layers. A steady state infiltration technique was used to control matric suction profiles in the sand layer prior to shaking. The obtained results from these...