# Elias ParaskevopoulosREDI Engineering Solutions

Elias Paraskevopoulos

PhD, Civil Engineer

## About

62

Publications

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362

Citations

## Publications

Publications (62)

Co-simulation techniques are widely used to enable global simulation of a coupled mechanical system via composition of simulators. Within this work, the focus is initially placed on a new scheme for the numerical integration of each subsystem since the corresponding accuracy affects directly the correct solution of a decomposed model. Following tha...

In this study, a review is presented of recent work of the authors on a class of multibody dynamic systems, involving bilateral motion constraints. First, the Analytical Dynamics framework is adopted and the basic theoretical ingredients of a method leading to a new set of equations of motion are presented. According to this method, the motion cons...

Co-simulation techniques are widely used to enable global simulation of a coupled system via composition of simulators. Herein, a novel co-simulation approach is developed and presented for mechanical systems, where the focus is placed on the proper decomposition of the initial system into two (or more) subsystems. Moreover, the master/orchestrator...

Based on past earthquake events, bridges are the most critical and most vulnerable component of road and rail transport systems, while bridge damage is related to substantial direct and indirect losses. For the case of railway bridges, the estimation of seismic fragility is a rather complex and
computationally demanding procedure given the real-ti...

Technical report with multiple authors (please refer to pdf), edited by Anastasios Sextos, Basil Margaris and Nikolaos Klimis. Coordinated by the Hellenic Association of Earthquake Engineering, the Institute of Engineering Seismology and Earthquake Engineering (ITSAK-EPPO) and Democritus University of Thrace with the collaboration of Aristotle Univ...

Bridges are the most critical and usually the most vulnerable structural component of a road network exposed to various hazards. Damage due to recent earthquakes worldwide highlighted the substantial direct and indirect financial losses related to partial or total collapse of critical bridge components and pointed to the need for reliable assessmen...

A new numerical integration method is presented for a class of multibody systems, exhibiting single frictional impacts. This method is a time-stepping scheme, involving incorporation of a novel return map into an augmented Lagrangian formulation, developed recently for systems with bilateral constraints. When an impact is detected, this map is appl...

Co-simulation is used to enable global simulation of a coupled system via composition of simulators. Namely, a co-simulation approach was developed and presented for mechanical systems with non-linear components. Specifically, a model two-degree-of-freedom oscillator, including Duffing type non-linearities, was investigated first by applying the me...

This paper presents a Dynamic Partitioning Method (DPM) to solve the vehicle-bridge interaction (VBI) problem via a set of exclusively second-order ordinary differential equations (ODEs). The partitioning of the coupled VBI problem follows a localized Lagrange multipliers approach that introduces auxiliary contact bodies between the vehicle’s wheel...

This work considers a class of multibody dynamic systems involving bilateral nonholonomic constraints. An appropriate set of equations of motion is employed first. This set is derived by application of Newton’s second law and appears as a coupled system of strongly nonlinear second-order ordinary differential equations in both the generalized coord...

Based on past earthquake events, bridges are the most critical and usually the most vulnerable components of road and rail transport systems, while bridge damage is related to substantial direct and indirect losses. In view of this, the need for direct and reliable assessment of bridge vulnerability has emerged, and several methodologies have been...

Based on past earthquake events, bridges are the most critical and usually the most vulnerable component of road and rail transport systems, while bridge damage is related to substantial direct and indirect losses. For the case of railway bridges, the estimation of seismic fragility is a rather complex and computationally demanding procedure due to...

This work considers a class of multibody dynamic systems involving bilateral nonholonomic constraints. An appropriate set of equations of motion is employed first. This set is derived by application of Newton’s second law and appears as a coupled system of strongly nonlinear second order ordinary differential equations in both the generalized coord...

This work presents a new numerical integration method for determining dynamics of a class of multibody systems involving impact and friction. Specifically, these systems are subject to a set of equality constraints and can exhibit single frictional impact events. Such events are associated to significant numerical stiffness, appearing in the equati...

This work presents a new return mapping, which can be an essential part in the numerical integration of the equations of motion of multibody systems involving impact events. For such systems, each unilateral constraint introduces a boundary hypersurface within the original configuration manifold, restricting the allowable motions on one side of thi...

The focus of this work is on dynamics of multibody systems subject to bilateral motion constraints. First, a new set of equations of motion is employed, expressed as a coupled system of strongly nonlinear second-order ordinary differential equations. After putting these equations in a weak form, the position, velocity and momentum type quantities a...

The scope of this research paper is to describe the mathematical formulation and develop a holistic and consistent methodology for dynamic analysis of coupled high-speed train-railway bridges. In the frame of the methodology proposed herein, appropriate numerical (discretization) schemes are introduced based on a suitable weak form relation dully t...

The new PPC Powerstation in Ptolemaida, Northern Greece, includes an asymmetric steel boiler house which comprises of an eccentrically braced central core combined with perimeter concentrically braced platforms, designed according to EC3 and EC8. The design by MHPSE provided for a 3D analysis of a condensed model, while the use of substructuring wa...

A systematic theoretical approach is presented, revealing dynamics of a class of multibody systems. Specifically, the motion is restricted by a set of bilateral constraints, acting simultaneously with a unilateral constraint, representing a frictional impact. The analysis is carried out within the framework of Analytical Dynamics and uses some conc...

This study focuses on the development of a new formulation, which describes the dynamics of a class of mechanical systems involving a single contact with friction. The whole process is performed within the general framework of analytical dynamics. At the same time, the efforts are assisted and enhanced by employing some fundamental tools of differe...

Some new theoretical and numerical results are presented on the dynamic response of a class of mechanical systems with equality motion constraints. At the beginning, the equations of motion of the corresponding unconstrained system are presented, first in strong and then in a weak form. Next, the formulation is extended to systems with holonomic an...

A systematic approach is presented first, leading to a new set of equations of motion for a class of mechanical systems subject to a single frictionless contact constraint. For this, some fundamental concepts of b-geometry are utilized and adapted to the general framework of Analytical Dynamics. These concepts refer to the theory of manifolds with...

This study presents a systematic approach, leading to a new set of equations of motion for a class of mechanical systems subject to a single frictionless contact constraint. To achieve this goal, some fundamental concepts of b-geometry are utilized and adapted to the general framework of Analytical Dynamics. These concepts refer to the theory of ma...

This study is focused on a class of discrete mechanical systems subject to equality motion constraints involving time and acatastatic terms. In addition, their original configuration manifold possesses time-dependent geometric properties. The emphasis is placed on a proper application of Newton’s law of motion. A key step is to consider the corresp...

Some new theoretical and numerical results are presented on the dynamic response of a class of mechanical systems with equality motion constraints. At the beginning, the equations of motion of the corresponding unconstrained system are presented, first in strong and then in a weak form. Next, the formulation is extended to systems with holonomic an...

A new set of equations of motion is presented for a class of mechanical systems subjected to equality motion constraints. Specifically, the systems examined satisfy a set of holonomic and/or nonholonomic scleronomic constraints. The main idea is to consider the equations describing the action of the constraints as an integral part of the overall pr...

Some new theoretical results are presented on modeling the dynamic response of a class of discrete mechanical systems subject to equality motion constraints. Both the development and presentation are facilitated by employing some fundamental concepts of differential geometry. At the beginning, the equations of motion of the corresponding unconstrai...

The Athens Opera House is a R/C building part of the Stavros Niarchos Cultural Center (SNFCC), a project designed by Renzo Piano, currently being constructed with a budget of 500 Million Euro. The ferrocement canopy of the Opera Building is made up of two ferrocement skins: the superior one (top skin) and the inferior one (bottom skin); they are co...

A set of numerical results is presented, obtained by direct integration of the equations of motion for a class of constrained systems. These equations are derived by applying a new theoretical approach, where the constraint action is considered as an integral part of the overall process leading to the equations of motion. As a consequence, a set of...

A new theoretical approach is presented for deriving an appropriate set of equations of motion for a class of mechanical systems subjected to motion constraints. This approach is facilitated by employing some fundamental concepts of differential geometry and can treat both holonomic and nonholonomic constraints simultaneously. The main idea is to c...

An investigation is carried out for deriving conditions on the correct application of Newton’s law of motion to mechanical systems subjected to constraints. It utilizes some fundamental concepts of differential geometry and treats both holonomic and anholonomic constraints. The focus is on establishment of conditions, so that the form of Newton’s l...

A systematic theoretical approach is presented first, in an effort to provide a complete and illuminating study on motion of a rigid body rotating about a fixed point. Since the configuration space of this motion is a differentiable manifold possessing group properties, this approach is based on some fundamental concepts of differential geometry. A...

A systematic theoretical approach is presented first, in an effort to provide a complete and
illuminating study on motion of a rigid body rotating about a fixed point. Since the configuration space of this motion is a differentiable manifold possessing group properties, this approach is based on some fundamental concepts of differential geometry. A...

This work is devoted to deriving and investigating conditions for the correct application of Newton’s law to mechanical systems subjected to motion constraints. It utilizes some fundamental concepts of differential geometry and treats both holonomic and nonholonomic constraints. This approach is convenient since it permits one to view the motion of...

A systematic theoretical approach is presented, in an effort to provide a complete and illuminating study on kinematics and dynamics of rigid bodies rotating about a fixed point. Specifically, this approach is based on some fundamental concepts of differential geometry, with particular reference to Lie group theory. This treatment is motivated by t...

An investigation is carried out for deriving conditions on the correct application of Newton's law of motion to mechanical systems subjected to constraints. It utilizes some fundamental concepts of differential geometry and treats both holonomic and anholonomic constraints. The focus is on establishment of conditions, so that the form of Newton's l...

A systematic theoretical approach is presented, in an effort to provide a complete and illuminating study on motion of a rigid body rotating about a fixed point. Since the configuration space of this motion is a differentiable manifold possessing group properties, this approach is based on some fundamental concepts of differential geometry. A key i...

This work aims at introducing structural sensitivity analysis capabilities into existing commercial finite element software codes for the purpose of mapping retrofit strategies for a broad group of structures including heritage-type buildings. More specifically, the first stage sensitivity analysis is implemented for the standard deterministic envi...

This paper is concerned with the variationally consistent incorporation of time dependent boundary conditions. The proposed
methodology avoids ad hoc procedures and is applicable to both linear as well as nonlinear problems. An integral formulation
of the dynamic problem serves as a basis for the imposition of the corresponding constraints, which a...

The elemental formulation presented in Part I of this study [E. Paraskevopoulos, D. Talaslidis, Reduction of excessive energy in the four-noded membrane quadrilateral element. Part I: Linear theory-compressible materials, Comput. Methods Appl. Mech. Engrg. 194 (2005) 3771–3796] is extended in a straightforward manner to problems with nearly incompr...

The objective of the paper is to set forth, in a consistent manner, reasons for the appearance of excessive energy in the four-noded membrane quadrilateral element and to propose a formulation leading to simple and reliable elements that are less sensitive to distortions of the geometrical shape. By presenting the differential geometry, emphasis is...

A variationally consistent methodology is presented, which yields diagonal mass matrices in two-dimensional elastodynamic problems. The proposed approach avoids ad hoc procedures and applies to arbitrary quadrilateral and triangular finite elements. As a starting point, a modified variational principle in elastodynamics is used. The time derivative...

A modular analysis package is assembled for assessing risk in typical industrial structural units such as steel storage tanks, due to extreme transient loads that are produced either as a result of chemical explosions in the form of atmospheric blasts or because of seismic activity in the form of ground motions. The main components of the methodolo...

In the present work, various sources of excessive energy in four-noded quadri-lateral finite elements for membrane and bending problems are presented. Emphasis is placed upon geometric parameters describing the departure of the quadrilateral elements from inherent parallelograms. A methodology based on a modified version of the func-tional of Hu-Wa...

In this work, a methodology is presented for assessing seismic risk in industrial structures storing potentially hazardous chemicals. The components of a modular analysis software package specifically developed for this purpose are as follows: (a) Description of the seismic loading using synthetic accelerograms generated for various levels of peak...

Financial support of theGreek State Institute of Scholarships (I.K.Y.) is greatly acknowledged. Abstract This paper presents an overview of computational techniques, recently introduced within the field of Finite Element programming and discusses how these techniques have affected development and have been incorporated in Finite Element codes. Obje...