Reza Attarnejad

Bio: Reza Attarnejad is an academic researcher from University of Tehran. The author has contributed to research in topics: Finite element method & Beam (structure). The author has an hindex of 17, co-authored 67 publications receiving 1040 citations. Previous affiliations of Reza Attarnejad include University College of Engineering & University of Kashan.

Effects of forward directivity on the response of soil–structure systems

Abstract: The effects of input parameters of pulse-like ground motions on the response of soil–structure systems are investigated through employing an ensemble of 64 ground motions. The soil and superstructure are idealised as a semi-infinite cone and a non-linear multiple-degrees-of-freedom shear building, respectively. The results confirm that the location of the critical storey is significantly affected by the pulse inputs and interacting parameters. Also, the pulse period ranges in which the critical storey complies with upper storeys are influenced considerably by interacting parameters. Moreover, there is a trade-off between pulse period and amplitude to determine the seismic demands of the structure.

Analysis of Euler-Bernoulli nanobeams: A mechanical-based solution

Abstract: The accuracy and efficiency of the elements proposed by finite element method (FEM) considerably depend on the interpolating functions namely shape functions used to formulate the displacement field within the element. In the present study, novel functions, namely basic displacements functions (BDFs), are introduced and exploited for structural analysis of nanobeams using finite element method based on Eringen’s nonlocal elasticity and EulerBernoulli beam theory. BDFs are obtained through solving the governing differential equation of motion of nanobeams using the power series method. Unlike the conventional methods which are almost categorized as displacement-based methods, the flexibility basis of the method ensures true satisfaction of equilibrium equations at any interior point of the element. Accordingly, shape functions and structural matrices are achieved in terms of BDFs by application of merely mechanical principles. In order to evaluate the competency and accuracy of the proposed method with different boundary conditions, several numerical examples with various boundary conditions are scrutinized. Carrying out several numerical examples, the results in stability analysis, free longitudinal vibration and free transverse vibration show a complete accordance with those in literature.

Dynamic analysis of dam-reservoir-foundation interaction using finite difference technique

Abstract: Time domain dynamic analysis of inclined dam-reservoir-foundation interaction was conducted using finite difference method (FDM). The Timoshenko beam theory and the Euler-Bernoulli beam theory were implemented to draw out governing equation of beam. The interactions between the dam and the soil were modeled by using a translational spring and a rotational spring. A Sommerfeld’s radiation condition at the infinity boundary of the fluid domain was adopted. The effects of the reservoir bottom absorption and surface waves on the dam-reservoir-foundation interaction due to the earthquake were studied. To avoid the instability of solution, a semi-implicit scheme was used for the discretization of the governing equation of dam and an explicit scheme was used for the discretization of the governing equation of fluid. The results show that as the slope of upstream dam increases, the hydrodynamic pressure on the dam is reduced. Moreover, when the Timoshenko beam theory is used, the system response increases.

Numerical free vibration analysis of higher-order shear deformable beams resting on two-parameter elastic foundation

Abstract: Free vibration analysis of higher-order shear deformation beam resting on one- and two-parameter elasticfoundation is studied using differential transform method (DTM) as a part of a calculation procedure. First,the governing differential equations of beam are derived in a general form considering the shear-freeboundary conditions (zero shear stress conditions at the top and bottom of a beam). Using DTM the derivedequations governing beams, followed by higher-order shear deformation model, Timoshenko model andBernoulli-Euler model are transformed to algebraic forms and a set of recurrence formulae is then derived.Upon imposing the boundary conditions of the beam at hand, a set of algebraic equations are obtained andexpressed in matrix form. Finally, the transverse natural frequencies of the beam are calculated through aniterative procedure. Several numerical examples have been carried out to demonstrate the competency ofthe present method and the results obtained by DTM are in good agreement with those in the literature.Afterward, the free vibration of beams followed up by different models (i.e. Bernoulli-Euler, Timoshenkoand different higher-order models) are taken into consideration.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Seismic Design Of Reinforced Concrete And Masonry Buildings

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