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Papers by Panagis Papadopoulos

Research paper thumbnail of Simplified Step-by-Step Nonlinear Static Program Investigating Equilibrium Conditions of Electrons in Atom and Ionization Energies: Case Study on Argon

Open Journal of Physical Chemistry

For investigation of equilibrium conditions of electrons in an atom, and Ionization Energies of E... more For investigation of equilibrium conditions of electrons in an atom, and Ionization Energies of Elements, a simplified deterministic static model is proposed. The electrons are initially uniformly and sparsely arranged on the outer surface of nucleus. Then, by taking into account the nucleus-electron interaction (attractive and repulsive) and the mutual electron-electron repulsions, and by a simple step-by-step nonlinear static analysis program, all the electrons are found to equilibrate on the outer surface of the same sphere, which is concentric and larger than nucleus. In a second stage, starting from an equilibrium sphere of electrons, one of the electrons is subjected to gradual forced removal, radially and outwards with respect to nucleus. Within each removal step, the produced work increment is determined and the increments are summed. When no more significant attraction is exerted by nucleus to removed electron, the total work gives the Ionization Energy. After removing of single electron, the remaining electrons fall on a lower shell, that is, they equilibrate on the outer surface of a smaller concentric sphere. For nucleus-electron interaction, an L-J (Lennard-Jones) type curve, attractive and repulsive, is adopted. When the parameter of this curve is n > 1.0, the Ionization Energy exhibits an upper bound. As parameter n increases from 1.0 up to 2.0, the attractive potential of L-J curve is gradually weakened. The proposed How to cite this paper: Papadopoulos,

Research paper thumbnail of Numerical study on the behavior of cables of cable-stayed bridges

Research paper thumbnail of Nonlinear seismic analysis of R/C frames by network models

Research paper thumbnail of Analysis of a portal steel frame subject to fire by use of a truss model

Research paper thumbnail of Comparison of Codes and Truss model requirements for Confinement

Research paper thumbnail of A simple program for the dynamic analysis of network models

Research paper thumbnail of A truss model with structural instability for the confinement of concrete columns

Research paper thumbnail of A truss model for the confinement of concrete columns

Research paper thumbnail of Comparison of a truss model for confinement with UBC and NZS requirements

Research paper thumbnail of Nonlinear analysis of infilled plane RC frames

Research paper thumbnail of Simple analysis of RC frames with soft first story

Research paper thumbnail of Amount of confinement preventing global instability of a RC column

Research paper thumbnail of A network model with substructures for seismic analysis of RC frames

Research paper thumbnail of Analysis of steel frame with pitched roof exposed to fire by a truss model

Research paper thumbnail of Recent Developments in Engineering Research Vol. 4

Research paper thumbnail of Simplified non-linear seismic analysis of infilled reinforced concrete frames

Earthquake Engineering & Structural Dynamics, 2004

The N2 method for simpliÿed non-linear seismic analysis has been extended in order to make it app... more The N2 method for simpliÿed non-linear seismic analysis has been extended in order to make it applicable to inÿlled reinforced concrete frames. Compared to the simple basic variant of the N2 method, two important di erences apply. A multi-linear idealization of the pushover curve, which takes into account the strength degradation which occurs after the inÿll fails, has to be made, and speciÿc reduction factors, developed in a companion paper, have to be used for the determination of inelastic spectra. It is shown that the N2 method can also be used for the determination of approximate summarized IDA curves. The proposed method was applied to two test buildings. The results were compared with the results obtained by non-linear dynamic analyses for three sets of ground motions, and a reasonable accuracy was demonstrated. A similar extension of the N2 method can be made to any structural system, provided that an appropriate speciÿc R-T relation is available. Copyright ? 2004 John Wiley & Sons, Ltd.

Research paper thumbnail of Simple Nonlinear Static Analysis Using Truss Models for Modeling Snap-through of Thin Shallow Arches

Applied Mechanics and Materials, 2012

In this paper, a truss model is used for the geometrically nonlinear static analysis of a thin sh... more In this paper, a truss model is used for the geometrically nonlinear static analysis of a thin shallow arch subject to snap-through. Thanks to the very simple geometry of a truss, the equilibrium conditions can be easily written and the global stiffness matrix can be easily updated with respect to the deformed structure, within each step of the analysis. A very coarse discretization is applied. For the geometrically nonlinear static analysis, a short computer program has been developed by displacement control of a plane truss model of a structure. This very short, fully documented computer program is applied on the geometrically nonlinear static analysis of a specific thin shallow arch subject to snap-through.

Research paper thumbnail of Achievements of Truss Models for Reinforced Concrete Structures

Open Journal of Civil Engineering, 2012

Research paper thumbnail of Numerical Study On The Behavior Of Cables OfCable-stayed Bridges

A simple method is proposed for the nonlinear static analysis of cable-stayed bridges, with empha... more A simple method is proposed for the nonlinear static analysis of cable-stayed bridges, with emphasis on the analysis of cables. The bridge is simulated by a plane truss model. A short computer program, with less than 200 Fortran instructions, is used, for the nonlinear static analysis, by incremental loading, of the above truss model. Geometric nonlinearities are taken into account by writing the equilibrium conditions with respect to deformed structure, within each step of the algorithm. The sag effect of cables is considered by assuming them to be the axial structural members with the equivalent elasticity modulus of Ernst. The above method is applied on a typical cable-stayed bridge with a central span of about 200m. The results are found to be in satisfactory approximation with other published data. Seismic inertia loads, parallel to the bridge axis, are applied to all the nodes of the truss. These loads combined with dead loads only, cause, in the back-stay, a state near slacke...

Research paper thumbnail of A simple method using a truss model for in-plane nonlinear static analysis of a cable-stayed bridge with a plate deck section

Engineering Structures, 2008

A beam element is simulated by a plane truss, which exhibits the same axial and flexural stiffnes... more A beam element is simulated by a plane truss, which exhibits the same axial and flexural stiffness. A short computer program has been developed for the nonlinear static analysis of a plane truss model of a beam structure, with incremental loading. The geometric nonlinearities, due to large displacements interacting with large axial forces, are taken into account by writing the

Research paper thumbnail of Simplified Step-by-Step Nonlinear Static Program Investigating Equilibrium Conditions of Electrons in Atom and Ionization Energies: Case Study on Argon

Open Journal of Physical Chemistry

For investigation of equilibrium conditions of electrons in an atom, and Ionization Energies of E... more For investigation of equilibrium conditions of electrons in an atom, and Ionization Energies of Elements, a simplified deterministic static model is proposed. The electrons are initially uniformly and sparsely arranged on the outer surface of nucleus. Then, by taking into account the nucleus-electron interaction (attractive and repulsive) and the mutual electron-electron repulsions, and by a simple step-by-step nonlinear static analysis program, all the electrons are found to equilibrate on the outer surface of the same sphere, which is concentric and larger than nucleus. In a second stage, starting from an equilibrium sphere of electrons, one of the electrons is subjected to gradual forced removal, radially and outwards with respect to nucleus. Within each removal step, the produced work increment is determined and the increments are summed. When no more significant attraction is exerted by nucleus to removed electron, the total work gives the Ionization Energy. After removing of single electron, the remaining electrons fall on a lower shell, that is, they equilibrate on the outer surface of a smaller concentric sphere. For nucleus-electron interaction, an L-J (Lennard-Jones) type curve, attractive and repulsive, is adopted. When the parameter of this curve is n > 1.0, the Ionization Energy exhibits an upper bound. As parameter n increases from 1.0 up to 2.0, the attractive potential of L-J curve is gradually weakened. The proposed How to cite this paper: Papadopoulos,

Research paper thumbnail of Numerical study on the behavior of cables of cable-stayed bridges

Research paper thumbnail of Nonlinear seismic analysis of R/C frames by network models

Research paper thumbnail of Analysis of a portal steel frame subject to fire by use of a truss model

Research paper thumbnail of Comparison of Codes and Truss model requirements for Confinement

Research paper thumbnail of A simple program for the dynamic analysis of network models

Research paper thumbnail of A truss model with structural instability for the confinement of concrete columns

Research paper thumbnail of A truss model for the confinement of concrete columns

Research paper thumbnail of Comparison of a truss model for confinement with UBC and NZS requirements

Research paper thumbnail of Nonlinear analysis of infilled plane RC frames

Research paper thumbnail of Simple analysis of RC frames with soft first story

Research paper thumbnail of Amount of confinement preventing global instability of a RC column

Research paper thumbnail of A network model with substructures for seismic analysis of RC frames

Research paper thumbnail of Analysis of steel frame with pitched roof exposed to fire by a truss model

Research paper thumbnail of Recent Developments in Engineering Research Vol. 4

Research paper thumbnail of Simplified non-linear seismic analysis of infilled reinforced concrete frames

Earthquake Engineering & Structural Dynamics, 2004

The N2 method for simpliÿed non-linear seismic analysis has been extended in order to make it app... more The N2 method for simpliÿed non-linear seismic analysis has been extended in order to make it applicable to inÿlled reinforced concrete frames. Compared to the simple basic variant of the N2 method, two important di erences apply. A multi-linear idealization of the pushover curve, which takes into account the strength degradation which occurs after the inÿll fails, has to be made, and speciÿc reduction factors, developed in a companion paper, have to be used for the determination of inelastic spectra. It is shown that the N2 method can also be used for the determination of approximate summarized IDA curves. The proposed method was applied to two test buildings. The results were compared with the results obtained by non-linear dynamic analyses for three sets of ground motions, and a reasonable accuracy was demonstrated. A similar extension of the N2 method can be made to any structural system, provided that an appropriate speciÿc R-T relation is available. Copyright ? 2004 John Wiley & Sons, Ltd.

Research paper thumbnail of Simple Nonlinear Static Analysis Using Truss Models for Modeling Snap-through of Thin Shallow Arches

Applied Mechanics and Materials, 2012

In this paper, a truss model is used for the geometrically nonlinear static analysis of a thin sh... more In this paper, a truss model is used for the geometrically nonlinear static analysis of a thin shallow arch subject to snap-through. Thanks to the very simple geometry of a truss, the equilibrium conditions can be easily written and the global stiffness matrix can be easily updated with respect to the deformed structure, within each step of the analysis. A very coarse discretization is applied. For the geometrically nonlinear static analysis, a short computer program has been developed by displacement control of a plane truss model of a structure. This very short, fully documented computer program is applied on the geometrically nonlinear static analysis of a specific thin shallow arch subject to snap-through.

Research paper thumbnail of Achievements of Truss Models for Reinforced Concrete Structures

Open Journal of Civil Engineering, 2012

Research paper thumbnail of Numerical Study On The Behavior Of Cables OfCable-stayed Bridges

A simple method is proposed for the nonlinear static analysis of cable-stayed bridges, with empha... more A simple method is proposed for the nonlinear static analysis of cable-stayed bridges, with emphasis on the analysis of cables. The bridge is simulated by a plane truss model. A short computer program, with less than 200 Fortran instructions, is used, for the nonlinear static analysis, by incremental loading, of the above truss model. Geometric nonlinearities are taken into account by writing the equilibrium conditions with respect to deformed structure, within each step of the algorithm. The sag effect of cables is considered by assuming them to be the axial structural members with the equivalent elasticity modulus of Ernst. The above method is applied on a typical cable-stayed bridge with a central span of about 200m. The results are found to be in satisfactory approximation with other published data. Seismic inertia loads, parallel to the bridge axis, are applied to all the nodes of the truss. These loads combined with dead loads only, cause, in the back-stay, a state near slacke...

Research paper thumbnail of A simple method using a truss model for in-plane nonlinear static analysis of a cable-stayed bridge with a plate deck section

Engineering Structures, 2008

A beam element is simulated by a plane truss, which exhibits the same axial and flexural stiffnes... more A beam element is simulated by a plane truss, which exhibits the same axial and flexural stiffness. A short computer program has been developed for the nonlinear static analysis of a plane truss model of a beam structure, with incremental loading. The geometric nonlinearities, due to large displacements interacting with large axial forces, are taken into account by writing the