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structure-interaction
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Incorporation of Soil-Structure Interaction into seismic performance evaluation of buildings
, Article 8th US National Conference on Earthquake Engineering 2006, San Francisco, CA, 18 April 2006 through 22 April 2006 ; Volume 15 , 2006 , Pages 9008-9017 ; 9781615670444 (ISBN) ; Ghannad, M. A ; Sharif University of Technology
2006
Abstract
It has been known for many years that the type of soil under structures affects the structural performance during earthquakes. In fact, the soil affects the structural response in two ways, through the change in the free-field motion (usually known as the site effect) and due to Soil- Structure Interaction (SSI). The site effect has been included in the seismic codes from the most beginning. However, the SSI effect had not attracted much attention. The most significant intervention in this regard has been the 1978 inclusion of SSI in the tentative provisions of ATC3-06 in the United States, which is based on the results of studies on elastic response of soil structure systems. The effect of...
Effect of seismic wave propagation in massed medium on rate-dependent anisotropic damage growth in concrete gravity dams
, Article Frontiers of Structural and Civil Engineering ; Volume 15, Issue 2 , 2021 , Pages 346-363 ; 20952430 (ISSN) ; Mohammadnezhad, H ; Ghaemian, M ; Sharif University of Technology
Higher Education Press Limited Company
2021
Abstract
Seismic modeling of massive structures requires special caution, as wave propagation effects significantly affect the responses. This becomes more crucial when the path-dependent behavior of the material is considered. The coexistence of these conditions renders numerical earthquake analysis of concrete dams challenging. Herein, a finite element model for a comprehensive nonlinear seismic simulation of concrete gravity dams, including realistic soil-structure interactions, is introduced. A semi-infinite medium is formulated based on the domain reduction method in conjunction with standard viscous boundaries. Accurate representation of radiation damping in a half-space medium and wave...
Seismic behavior of a dolphin-type berth subjected to liquefaction induced lateral spreading: 1g large scale shake table testing and numerical simulations
, Article Soil Dynamics and Earthquake Engineering ; Volume 140 , 2021 ; 02677261 (ISSN) ; Haeri, S. M ; Raisianzadeh, J ; Sadeghi Meibodi, A ; Afzal Soltani, S ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The effects of liquefaction induced lateral spreading on the piles of a dolphin-type berth were investigated using 1 g large scale shake table testing accompanied by numerical simulations. For this purpose, various aspects of the response of the soil and the pile group to lateral spreading were considered. The results indicated that large bending moments were induced in the piles during lateral spreading and the downslope piles of the group received greater bending moments than the upslope one. The monotonic components of bending moments in the piles were reasonably predicted by the displacement based numerical approach using p-y springs when they were properly tuned for strength reduction...
On the development of a nonlinear time-domain numerical method for describing vortex-induced vibration and wake interference of two cylinders using experimental results
, Article Nonlinear Dynamics ; 2021 ; 0924090X (ISSN) ; Day, S ; Karimirad, M ; Khorasanchi, M ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
A nonlinear mathematical model is developed in the time domain to simulate the behaviour of two identical flexibly mounted cylinders in tandem while undergoing vortex-induced vibration (VIV). Subsequently, the model is validated and modified against experimental results. Placing an array of bluff bodies in proximity frequently happens in different engineering fields. Chimney stacks, power transmission lines and oil production risers are few engineering structures that may be impacted by VIV. The coinciding of the vibration frequency with the structure natural frequency could have destructive consequences. The main objective of this study is to provide a symplectic and reliable model capable...
Nonlinear pitch angle control of an onshore wind turbine by considering the aerodynamic nonlinearities and deriving an aeroelastic model
, Article Energy Systems ; 2021 ; 18683967 (ISSN) ; Moradi, H ; Tse, K. T ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this paper, the control problem of a wind turbine in region 3 (where the wind velocity is between the rated wind velocity and cut out wind velocity) has been investigated by considering the aerodynamic nonlinear behavior of the wind-structure interaction. The model has been developed by using the blade element momentum (BEM) theory to obtain the aerodynamic torque and aerodynamic loads in edgewise and flapwise directions. For validation, the aerodynamic behavior of the onshore NREL 5 MW turbine has been compared with the Fatigue, Aerodynamics, Structures, and Turbulence (FAST) aeroelastic code in terms of the power coefficient. Wind speed is modelled as a three-dimensional profile with...
Numerical modeling of interaction between flexible retaining wall and saturated clayey soil in undrained and drained conditions
, Article 4th International Conference on Soft Soil Engineering - Soft Soil Engineering, Vancouver, BC, 4 October 2006 through 6 October 2006 ; 2007 , Pages 493-498 ; 0415422809 (ISBN); 9780415422802 (ISBN) ; Pak, A ; Sharif University of Technology
2007
Abstract
In this article, behavior of cantilever retaining walls with various flexibilities, which retain saturated cohesive soil behind, is studied using numerical modeling. Generally, pattern of lateral earth pressure behind retaining walls is complex and this complexity becomes greater for clayey soils. In this investigation, effects of different wall bending stiffnesses, and backfill drainage conditions on the failure height and on the lateral earth pressure are investigated using finite elements. Comparison between the obtained results from numerical simulation and those based on empirical or conventional design methods indicate that soil-structure interaction and c drainage conditions play...
Numerical simulation of vortex-induced vibration of a smooth circular cylinder at the subcritical regime
, Article Proceedings of the Institution of Mechanical Engineers Part M: Journal of Engineering for the Maritime Environment ; Volume 236, Issue 4 , 2022 , Pages 916-937 ; 14750902 (ISSN) ; Nemati Kourabbasloo, N ; Mohtat, P ; Tanha, A ; Sharif University of Technology
SAGE Publications Ltd
2022
Abstract
The present paper focuses on the simulation of vortex-induced vibration (VIV) of a rigid, smooth circular cylinder with elastic supports subject to a cross-flow at the subcritical regime of Reynolds number, 30,000
Analytical and numerical biaxial bending analysis of deepwater riser due to vortex-induced vibration
, Article Journal of Marine Science and Technology (Japan) ; Volume 27, Issue 1 , 2022 , Pages 492-507 ; 09484280 (ISSN) ; Komachi, Y ; Sharif University of Technology
Springer Japan
2022
Abstract
Previous studies of analysis and prediction of marine risers responses usually focus on vortex-induced vibration (VIV) of cross-flow (CF) direction rather than in-line (IL). Recent studies show that responses of IL direction tend to dominate in some cases. Responses of long riser due to biaxial bending of IL and CF VIV are investigated. Closed-form formulas are derived for estimating maximum normal stress due to the biaxial moment of CF/IL VIV and relations for estimating biaxial stress using CF values are presented. Analytical results are compared with numerical results of the time domain model and a good correlation is observed. It is shown that for tension and bending-controlled modes of...
Investigating the behavior of cracks in welded zones of supporting structure of spherical pressure vessel under seismic loading
, Article Journal of Constructional Steel Research ; Volume 191 , 2022 ; 0143974X (ISSN) ; Ghazi, M ; Adibnazari, S ; Rofooei, F. R ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
In this paper, the numerical studies on the semi-elliptical crack behavior in different locations of welded zones in the supporting structure of a spherical pressure vessel under an earthquake are presented. The cracks in the welded zones of supporting structures under earthquake effects may jeopardize the safety of spherical pressure vessels and result in catastrophic failure. A detailed finite element sub-modeling technique is carried out to compute the mixed-mode stress intensity factors along the crack front. Furthermore, crack behavior with different aspect ratios a/c: 0.25, 0.5, and 0.75 at the weld and the heat-affected zone of the supporting structure is evaluated. The...
Three-dimensional numerical analysis of corner effect of an excavation supported by ground anchors
, Article International Journal of Geotechnical Engineering ; Volume 16, Issue 7 , 2022 , Pages 903-915 ; 19386362 (ISSN) ; Ahmadi, M. M ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
This paper presents a case study and numerical simulations of a corner of a deep excavation in Tehran supported by soldier piles and ground anchors. This study focuses on the differences between 2D and 3D numerical modelling in estimating the wall deflection at the corner locations of the excavation. Furthermore, the performance of modelling with Mohr–Coulomb constitutive law was compared with the result of a hardening soil model. The modelling procedure was calibrated against a full-scale instrumented tieback wall at Texas A&M University and the monitoring data of the excavation project. The results indicated that the hardening soil model yields reasonable predictions of wall deflection in...
Blind identification of soil-structure systems
, Article Soil Dynamics and Earthquake Engineering ; Volume 45 , February , 2013 , Pages 56-69 ; 02677261 (ISSN) ; Ghannad, M. A ; Taciroglu, E ; Sharif University of Technology
2013
Abstract
Surrounding soil can drastically influence the dynamic response of buildings during strong ground shaking. Soil's flexibility decreases the natural frequencies of the system; and in most cases, soil provides additional damping due to material hysteresis and radiation. The additional damping forces, which are in non-classical form, render the mode shapes of the soil-structure system complex-valued. The response of a soil-foundation system can be compactly represented through impedance functions that have real and imaginary parts representing the stiffness and damping of the system, respectively. These impedance functions are frequency-dependent, and their determination for different...
Fluid-structure interaction analysis in microfluidic devices: A dimensionless finite element approach
, Article International Journal for Numerical Methods in Fluids ; Volume 68, Issue 9 , 2012 , Pages 1073-1086 ; 02712091 (ISSN) ; Movahhedy, M. R ; Assempour, A ; Sharif University of Technology
2012
Abstract
In this paper, the so-called small time-step instability in finite element simulation of the fluid part is considered in fluid-structure interaction (FSI) problems in which a high-frequency vibrating structure interacts with an incompressible fluid. Such a situation is common in many microfluid manipulating devices. A treatment has been proposed that uses the dimensionless set of FSI governing equations in order to scale up the problem time step to a proper level that precludes the potential small time-step instability. Two-dimensional and three-dimensional finite element simulations of a mechanical micropumping device are performed to verify the efficiency of the presented approach. Solid...
Bit error probability analysis of UWB communications with a relay node
, Article IEEE Transactions on Wireless Communications ; Volume 9, Issue 2 , 2010 , Pages 802-813 ; 15361276 (ISSN) ; Nasiri Kenari, M ; Aazhang, B ; Sharif University of Technology
2010
Abstract
In this paper, the extension of cooperative communication to the context of TH-UWB is investigated. In particular, the average bit error probability (BEP) is provided for cooperative TH-UWB systems with decode-and-forward relaying protocol. In the considered relay network, UWB links among the nodes are modeled according to IEEE 802.15.4a standards. Our methodology is based on computing the Characteristic Function (CF) of the decision variable at the destination terminal. We use Gaussian quadrature numerical method to approximate the CF of interference component appeared in decision variable term. This technique permits to predict the system performance in different IEEE 802.15.4a defined...
Response of the beams on random Pasternak foundations subjected to harmonic moving loads
, Article Journal of Mechanical Science and Technology ; Volume 23, Issue 11 , 2010 , Pages 3013-3023 ; 1738494X (ISSN) ; Kargarnovin, M. H ; Sharif University of Technology
2010
Abstract
Dynamic response of infinite beams supported by random viscoelastic Pasternak foundation subjected to harmonic moving loads is studied. Vertical stiffness in the support is assumed to follow a stochastic homogeneous field consisting of a small random variation around a deterministic mean value. By employing the first order perturbation theory and calculating appropriate Green's functions, the variance of the deflection and bending moment are obtained analytically in integral forms. To simulate the induced uncertainty, two practical cases of cosine and exponential covariance are utilized. A frequency analysis is performed and influences of the correlation length of the stiffness variation on...
Simulation of low density lipoprotein (LDL) permeation into multilayer coronary arterial wall: interactive effects of wall shear stress and fluid-structure interaction in hypertension
, Article Journal of Biomechanics ; Volume 67 , 2018 , Pages 114-122 ; 00219290 (ISSN) ; Nikmaneshi, M. R ; Firoozabadi, B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Due to increased atherosclerosis-caused mortality, identification of its genesis and development is of great importance. Although, key factors of the origin of the disease is still unknown, it is widely believed that cholesterol particle penetration and accumulation in arterial wall is mainly responsible for further wall thickening and decreased rate of blood flow during a gradual progression. To date, various effective components are recognized whose simultaneous consideration would lead to a more accurate approximation of Low Density Lipoprotein (LDL) distribution within the wall. In this research, a multilayer Fluid-Structure Interaction (FSI) model is studied to simulate the penetration...
In silico study of patient-specific magnetic drug targeting for a coronary LAD atherosclerotic plaque
, Article International Journal of Pharmaceutics ; Volume 559 , 2019 , Pages 113-129 ; 03785173 (ISSN) ; Amani, A ; Forouzandehmehr, M ; Ghoytasi, I ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Coronary artery disease is the first cause of death across the world. Targeted delivery of therapeutics through controlled release of micro- and nano-particles remains a very capable approach to develop new strategies in treating restenosis and atherosclerotic plaques. In this research, to produce the arterial geometry, an image-processing was done using CT-scan images of a LAD coronary artery. After implementing the finite element mesh, the Fluid-Structure Interaction (FSI) simulation based on physiological boundary conditions was performed. Next, a Lagrangian description of particles dynamics in a non-Newtonian blood flow considering momentum equation of motion for each particle and the...
Evaluation of dynamic properties of a calcite cemented gravely sand
, Article Geotechnical Earthquake Engineering and Soil Dynamics IV Congress 2008 - Geotechnical Earthquake Engineering and Soil Dynamics, Sacramento, CA, 18 May 2008 through 22 May 2008 ; Issue 181 , 2008 ; 08950563 (ISSN); 9780784409756 (ISBN) ; Shakeri, M. R ; Shahcheraghi, S. A ; Sharif University of Technology
2008
Abstract
Understanding of the effect of cementation on dynamic behaviour of cemented soil in an earthquake prone area could be crucial for earthquake resistance design. The major section of the city of Tehran has been developed on cemented coarse-grained alluvium. In order to understand the dynamic behaviour of this soil, a series of undrained cyclic triaxial tests were performed on uncemented and artificially calcite-cemented samples. In this paper, two dynamic parameters including dynamic shear modulus and damping ratio based on different definitions are investigated. In this regard the effects of cement content, confining pressure and cyclic deviatoric stress were studied as well. In general by...
Targeted drug delivery of magnetic microbubble for abdominal aortic aneurysm: an in silico study
, Article Biomechanics and Modeling in Mechanobiology ; Volume 21, Issue 2 , 2022 , Pages 735-753 ; 16177959 (ISSN) ; Ebrahimi, S ; Ghorbani, G ; Alishiri, M ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Targeted drug delivery (TDD) to abdominal aortic aneurysm (AAA) using a controlled and efficient approach has recently been a significant challenge. In this study, by using magnetic microbubbles (MMBs) under a magnetic field, we investigated the MMBs performance in TDD to AAA based on the amount of surface density of MMBs (SDMM) adhered to the AAA lumen. The results showed that among the types of MMBs studied in the presence of the magnetic field, micromarkers are the best type of microbubble with a −50 % increase in SDMM adhered to the critical area of AAA. The results show that applying a magnetic field causes the amount of SDMM adhered to the whole area of AAA to increase −1.54 times...
Effect of cysteine oxidation in SARS-CoV-2 receptor-binding domain on its interaction with two cell receptors: Insights from atomistic simulations
, Article Journal of Chemical Information and Modeling ; Volume 62, Issue 1 , 2022 , Pages 129-141 ; 15499596 (ISSN) ; Privat Maldonado, A ; Yusupov, M ; Rahnama, S ; Bogaerts, A ; Ejtehadi, M. R ; Sharif University of Technology
American Chemical Society
2022
Abstract
Binding of the SARS-CoV-2 S-glycoprotein to cell receptors is vital for the entry of the virus into cells and subsequent infection. ACE2 is the main cell receptor for SARS-CoV-2, which can attach to the C-terminal receptor-binding domain (RBD) of the SARS-CoV-2 S-glycoprotein. The GRP78 receptor plays an anchoring role, which attaches to the RBD and increases the chance of other RBDs binding to ACE2. Although high levels of reactive oxygen and nitrogen species (RONS) are produced during viral infections, it is not clear how they affect the RBD structure and its binding to ACE2 and GRP78. In this research, we apply molecular dynamics simulations to study the effect of oxidation of the highly...
Sensitivity analysis of jacket-type offshore platforms under extreme waves
, Article Journal of Constructional Steel Research ; Volume 83 , 2013 , Pages 147-155 ; 0143974X (ISSN) ; Bahaari, M. R ; Bagheri, V ; Ebrahimian, H ; Sharif University of Technology
2013
Abstract
Jacket-type offshore platforms play an important role in oil and gas industries in shallow and intermediate water depths such as Persian Gulf region. Such important structures need accurate considerations in analysis, design and assessment procedures. In this paper, nonlinear response of jacket-type platforms against extreme waves is examined utilizing sensitivity analyses. Results of this paper can reduce the number of random variables and consequently the computational effort in reliability analysis of jacket platforms, noticeably. Effects of foundation modeling have been neglected in majority of researches on the response of jacket platforms against wave loads. As nonlinear response of...