The Experts below are selected from a list of 505320 Experts worldwide ranked by ideXlab platform

Dieter Cremer - One of the best experts on this subject based on the ideXlab platform.

  • Calculation of response properties with the normalized elimination of the small Component Method
    International Journal of Quantum Chemistry, 2013
    Co-Authors: Michael Filatov, Wenli Zou, Dieter Cremer
    Abstract:

    The normalized elimination of the small Component Method is a first principles two-Component relativistic approach that leads to the Dirac-exact description of one-electron systems. Therefore, it is an ideal starting point for developing procedures, by which first- and second-order response properties can be routinely calculated. We present algorithms and Methods for the calculation of molecular response properties such as geometries, dipole moments, hyperfine structure constants, vibrational frequencies and force constants, electric polarizabilities, infrared intensities and so forth. The described formalisms are applied to molecules containing mercury and other heavy elements, which require a relativistic treatment. Perspectives for the future development and application of Dirac-exact Methods are outlined. © 2013 Wiley Periodicals, Inc.

  • spin orbit coupling calculations with the two Component normalized elimination of the small Component Method
    Journal of Chemical Physics, 2013
    Co-Authors: Michael Filatov, Dieter Cremer
    Abstract:

    A new algorithm for the two-Component Normalized Elimination of the Small Component (2cNESC) Method is presented and tested in the calculation of spin-orbit (SO) splittings for a series of heavy atoms and their molecules. The 2cNESC is a Dirac-exact Method that employs the exact two-Component one-electron Hamiltonian and thus leads to exact Dirac SO splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)10.1103/PhysRevB.62.7809]. The use of the screened nucleus potential for the two-electron SO interaction leads to accurate spinor energy splittings, for which the deviations from the accurate Dirac Fock-Coulomb values are on the average far below the deviations observed for other effective one-electron SO operators. For hydrogen halides HX (X = F, Cl, Br, I, At, and Uus) and mercury dihalides HgX2 (X = F, Cl, Br, I) ...

  • An improved algorithm for the normalized elimination of the small-Component Method
    Theoretical Chemistry Accounts, 2011
    Co-Authors: Michael Filatov, Dieter Cremer
    Abstract:

    A new algorithm for the iterative solution of the normalized elimination of the small Component (NESC) Method is presented that is less costly than previous algorithms and that is based on (1) solving the NESC equations for the uncontracted rather than contracted basis (“First-Diagonalize-then-Contract”), (2) a new iterative procedure for obtaining the NESC Hamiltonian (“iterative TU algorithm”), (3) the renormalization scheme connected to the picture change, and (4) a finite nucleus model with a Gaussian charge distribution. The accuracy of NESC energies, which match those of 4-Component Dirac calculations, is demonstrated. Test calculations with CCSD(T), DFT, and large basis sets including high angular momentum basis functions (f,g,h,i) are presented to prove the general applicability of the new NESC algorithm. Comparison with other algorithms of solving the NESC equations are shortly discussed and time savings are presented.

Alfonsas Daniūnas - One of the best experts on this subject based on the ideXlab platform.

  • A Component Method for cold-formed steel beam-to-column bolted gusset plate joints
    Thin-Walled Structures, 2018
    Co-Authors: Žilvinas Bučmys, Jean-pierre Jaspart, Alfonsas Daniūnas, Jean-françois Demonceau
    Abstract:

    Abstract Cold-formed steel elements are being used more frequently on construction sites because of the good strength-to-cost ratio. Researches on such structures show that, in most cases, the behaviour of the constitutive joints is semi-rigid. However, insufficient studies are published examining the properties of these joints. This paper presents a study of cold-formed steel bolted gusset plate connections based on the Component Method approach. The Component Method considers any joint as a set of individual basic Components. In this procedure, the joints are analysed using mechanical models that are able to simulate moment – rotation M – φ relationship. In this paper the joint is analysed as made of three springs: beam bolt group, column bolt group and gusset plate. A “three springs” mechanical model and a technique to calculate joint stiffness is presented. The results predicted through the proposed mechanical model are validated through comparisons to experimental and finite element results.

  • Component Method in the Strength Evaluation of Cold-formed Steel Joints
    Procedia Engineering, 2017
    Co-Authors: Žilvinas Bučmys, Alfonsas Daniūnas
    Abstract:

    Abstract Nowadays, there is a growing tendency in the use of cold formed constructions, which may be explained by good strength to cost ratio. Thus, the goal of this paper is to investigate the strength of cold-formed steel beam-to-column bolted gusset-plate joints. In the paper the model of moment resistance of such joints based on the Component Method is presented. The calculation of resistance of steel Components is based on EN 1993-1-8 and EN 1993-1-1. Two types of gusset plates are investigated: I-shape and T-shape. The developed model is well in line with the full-scale experimental results.

  • Use of Component Method in the analysis of timber-steel connections
    2015
    Co-Authors: Alfonsas Daniūnas, Tomas Gečys
    Abstract:

    The use of Component Method for determining the moment resistance of an innovative beam-to-beam timber-steel connection is presented in the paper. The calculation of resistance of steel Components is conducted based on EN 1993-1-8. The resistance of timber Components is determined according to EN 1995-1-1, and based on the fullscale laboratory experiments and the finite element modelling results. The developed moment resistance calculation model, based on the Component Method, is well in line with the full-scale experimental and finite element modelling results.

  • analysis of the steel frames with the semi rigid beam to beam and beam to column knee joints under bending and axial forces
    Engineering Structures, 2008
    Co-Authors: Alfonsas Daniūnas, Kestutis Urbonas
    Abstract:

    This paper presents an analysis of framework structures with semi-rigid joints. The semi-rigid end-plate bolted joints are subjected to bending and tension or a compression axial force. Usually the influence of an axial force on joint rotational stiffness is neglected. In some cases, the level of axial forces in the joints of structures can be significant and has a profound influence on characteristics of semi-rigid joints. One of the most popular practical Methods permitting the determination of rotational stiffness and moment resistance of a joint is the so-called Component Method. The extension of the Component Method for evaluating the influence of bending moment and axial force on the rotational stiffness and moment resistance of a joint and an application to the analysis of framework structures are presented in the paper. The numerical results of calculations of steel frameworks are presented in this paper as well. The study shows that the estimation of axial force influence to rotation stiffness characteristics of the joint has significant influence on the distribution of internal forces and displacements of steel framework.

  • behaviour of semi rigid steel beam to beam joints under bending and axial forces
    Journal of Constructional Steel Research, 2006
    Co-Authors: Kestutis Urbonas, Alfonsas Daniūnas
    Abstract:

    Abstract This paper presents an analysis of semi-rigid beam-to-beam end-plate bolted joints that are subjected to bending and tension or a compression axial force. Usually the influence of axial force on joint rotational stiffness is neglected. According to EC3, the axial load, which is less than 10% of plastic resistance of the connected member under axial force, may be disregarded in the calculation of characteristics of a joint. Actually, the level of axial forces in joints of structures can be significant and has a significant influence on characteristics of semi-rigid joints. One of the most popular practical Methods permitting the determination of rotational stiffness and moment resistance of a joint is the so-called Component Method. The extension of the Component Method for evaluating the influence of bending moment and axial force on the rotational stiffness and moment resistance of a joint are presented in the paper. The numerical results of calculations of characteristics of joints and calculations of steel framework are presented in this paper as well.

Jean-pierre Jaspart - One of the best experts on this subject based on the ideXlab platform.

  • A Component Method for cold-formed steel beam-to-column bolted gusset plate joints
    Thin-Walled Structures, 2018
    Co-Authors: Žilvinas Bučmys, Jean-pierre Jaspart, Alfonsas Daniūnas, Jean-françois Demonceau
    Abstract:

    Abstract Cold-formed steel elements are being used more frequently on construction sites because of the good strength-to-cost ratio. Researches on such structures show that, in most cases, the behaviour of the constitutive joints is semi-rigid. However, insufficient studies are published examining the properties of these joints. This paper presents a study of cold-formed steel bolted gusset plate connections based on the Component Method approach. The Component Method considers any joint as a set of individual basic Components. In this procedure, the joints are analysed using mechanical models that are able to simulate moment – rotation M – φ relationship. In this paper the joint is analysed as made of three springs: beam bolt group, column bolt group and gusset plate. A “three springs” mechanical model and a technique to calculate joint stiffness is presented. The results predicted through the proposed mechanical model are validated through comparisons to experimental and finite element results.

  • Component Method for steel column bases
    2016
    Co-Authors: František Wald, Zdeněk Sokol, Martin Steenhuis, Jean-pierre Jaspart
    Abstract:

    This paper presents the application of the Component Method to steel column bases. The decomposition of the connection into Components is described. An analytical model is presented to determine the moment resistance and the rotational stiffness of column bases under axial forces. The analytical model is verified with test results. A sensitivity study of the base plate thickness and the anchor bolt length is presented

  • Application of the Component Method to structural joints with dowel fasteners in timber construction
    2005
    Co-Authors: N. François, A. Mertens, Jean-pierre Jaspart
    Abstract:

    A general procedure for the evaluation of the mechanical properties of structural joints, named “Component Method” [01], is now available from intensive research works at the European level. This procedure allows the analytical prediction of the resistance, but also of the stiffness and the deformation capacity, of structural joints under external forces (axial or shear forces, bending moments, ...). In the present paper, timber joints with dowel fasteners are considered. Two Components may be identified: the “dowel fastener in bending and shear” and the “timber member in embedding”.

  • designing structural joints according to eurocodes
    2000
    Co-Authors: Jean-pierre Jaspart
    Abstract:

    In Eurocode 3 [1] on steel buildings, the design of structural joints is covered by Chapter 6 and, for joints between H or I profiles, by Annex J. During the recent revision of Annex J [2], a new comprehensive design approach for the design of joints has been implemented and the so-called “Component Method” has been introduced as a basic procedure for the derivation of the stiffness and strength properties of the structural joints, whatever is the joint configuration (single-sided or double-sided beam-to-column joints, beam splices, …) and the connection type (welded connections, bolted connections with end-plates, flange cleats, …). More recently, the application of the Component Method has been extended to base plates configurations [3] and composite steel-concrete joints [4].

  • Application of the Component Method to column bases
    Journal of Constructional Steel Research, 1998
    Co-Authors: Jean-pierre Jaspart, D. Vandegans
    Abstract:

    Abstract Column bases transfer reactions from the structure to the foundation. When subjected to normal forces, shear forces and in-plane bending moments, they deform, particularly in rotation. This rotational behaviour is usually idealized as pinned or fully rigid. But in most of the cases column bases have a high semi-rigid behaviour which influences significantly the global frame response. In this paper, a mechanical model to predict their moment-rotation response is presented. To achieve this goal, the Component Method described in Annex J of Eurocode 3 is used and extended. According to the Component Method, any structural joint is considered as a set of individual Components and the determination of its mechanical properties as strength and rotational stiffness includes three main steps: (i) definition of the constitutive Components, (ii) evaluation of their mechanical properties and (iii) assembly of the Components to derive the joint properties. Lastly, comparisons of the mechanical model with experimental laboratory tests on column bases are performed.

Kestutis Urbonas - One of the best experts on this subject based on the ideXlab platform.

  • influence of the semi rigid bolted steel joints on the frame behaviour
    Journal of Civil Engineering and Management, 2010
    Co-Authors: Alfonsas Daniūnas, Kestutis Urbonas
    Abstract:

    Abstract This research work describes the analysis of steel semi rigid joints that are subjected to bending and tension or compression. The main attention is focussed on the beam‐to‐beam and plate bolted joints. Usually influence of axial force is neglected. In fact, the level of tension or compression of axial force can be significant and has some impact on joint behaviour and on its stiffness and strength characteristics. Nowadays the most powerful Method for the estimation of joints characteristics is the Component Method. The adaptation of the Component Method for the determination of joints characteristics under bending ant axial forces is shown in the paper. Some numerical results of calculations of steel frameworks are presented in this paper as well (Daniūnas and Urbonas 2008).

  • analysis of the steel frames with the semi rigid beam to beam and beam to column knee joints under bending and axial forces
    Engineering Structures, 2008
    Co-Authors: Alfonsas Daniūnas, Kestutis Urbonas
    Abstract:

    This paper presents an analysis of framework structures with semi-rigid joints. The semi-rigid end-plate bolted joints are subjected to bending and tension or a compression axial force. Usually the influence of an axial force on joint rotational stiffness is neglected. In some cases, the level of axial forces in the joints of structures can be significant and has a profound influence on characteristics of semi-rigid joints. One of the most popular practical Methods permitting the determination of rotational stiffness and moment resistance of a joint is the so-called Component Method. The extension of the Component Method for evaluating the influence of bending moment and axial force on the rotational stiffness and moment resistance of a joint and an application to the analysis of framework structures are presented in the paper. The numerical results of calculations of steel frameworks are presented in this paper as well. The study shows that the estimation of axial force influence to rotation stiffness characteristics of the joint has significant influence on the distribution of internal forces and displacements of steel framework.

  • behaviour of semi rigid steel beam to beam joints under bending and axial forces
    Journal of Constructional Steel Research, 2006
    Co-Authors: Kestutis Urbonas, Alfonsas Daniūnas
    Abstract:

    Abstract This paper presents an analysis of semi-rigid beam-to-beam end-plate bolted joints that are subjected to bending and tension or a compression axial force. Usually the influence of axial force on joint rotational stiffness is neglected. According to EC3, the axial load, which is less than 10% of plastic resistance of the connected member under axial force, may be disregarded in the calculation of characteristics of a joint. Actually, the level of axial forces in joints of structures can be significant and has a significant influence on characteristics of semi-rigid joints. One of the most popular practical Methods permitting the determination of rotational stiffness and moment resistance of a joint is the so-called Component Method. The extension of the Component Method for evaluating the influence of bending moment and axial force on the rotational stiffness and moment resistance of a joint are presented in the paper. The numerical results of calculations of characteristics of joints and calculations of steel framework are presented in this paper as well.

  • behaviour of semi rigid steel beam to beam joints under bending and axial forces
    Journal of Constructional Steel Research, 2006
    Co-Authors: Kestutis Urbonas, Alfonsas Daniūnas
    Abstract:

    Abstract This paper presents an analysis of semi-rigid beam-to-beam end-plate bolted joints that are subjected to bending and tension or a compression axial force. Usually the influence of axial force on joint rotational stiffness is neglected. According to EC3, the axial load, which is less than 10% of plastic resistance of the connected member under axial force, may be disregarded in the calculation of characteristics of a joint. Actually, the level of axial forces in joints of structures can be significant and has a significant influence on characteristics of semi-rigid joints. One of the most popular practical Methods permitting the determination of rotational stiffness and moment resistance of a joint is the so-called Component Method. The extension of the Component Method for evaluating the influence of bending moment and axial force on the rotational stiffness and moment resistance of a joint are presented in the paper. The numerical results of calculations of characteristics of joints and calculations of steel framework are presented in this paper as well.

Michael Filatov - One of the best experts on this subject based on the ideXlab platform.

  • Calculation of response properties with the normalized elimination of the small Component Method
    International Journal of Quantum Chemistry, 2013
    Co-Authors: Michael Filatov, Wenli Zou, Dieter Cremer
    Abstract:

    The normalized elimination of the small Component Method is a first principles two-Component relativistic approach that leads to the Dirac-exact description of one-electron systems. Therefore, it is an ideal starting point for developing procedures, by which first- and second-order response properties can be routinely calculated. We present algorithms and Methods for the calculation of molecular response properties such as geometries, dipole moments, hyperfine structure constants, vibrational frequencies and force constants, electric polarizabilities, infrared intensities and so forth. The described formalisms are applied to molecules containing mercury and other heavy elements, which require a relativistic treatment. Perspectives for the future development and application of Dirac-exact Methods are outlined. © 2013 Wiley Periodicals, Inc.

  • spin orbit coupling calculations with the two Component normalized elimination of the small Component Method
    Journal of Chemical Physics, 2013
    Co-Authors: Michael Filatov, Dieter Cremer
    Abstract:

    A new algorithm for the two-Component Normalized Elimination of the Small Component (2cNESC) Method is presented and tested in the calculation of spin-orbit (SO) splittings for a series of heavy atoms and their molecules. The 2cNESC is a Dirac-exact Method that employs the exact two-Component one-electron Hamiltonian and thus leads to exact Dirac SO splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)10.1103/PhysRevB.62.7809]. The use of the screened nucleus potential for the two-electron SO interaction leads to accurate spinor energy splittings, for which the deviations from the accurate Dirac Fock-Coulomb values are on the average far below the deviations observed for other effective one-electron SO operators. For hydrogen halides HX (X = F, Cl, Br, I, At, and Uus) and mercury dihalides HgX2 (X = F, Cl, Br, I) ...

  • An improved algorithm for the normalized elimination of the small-Component Method
    Theoretical Chemistry Accounts, 2011
    Co-Authors: Michael Filatov, Dieter Cremer
    Abstract:

    A new algorithm for the iterative solution of the normalized elimination of the small Component (NESC) Method is presented that is less costly than previous algorithms and that is based on (1) solving the NESC equations for the uncontracted rather than contracted basis (“First-Diagonalize-then-Contract”), (2) a new iterative procedure for obtaining the NESC Hamiltonian (“iterative TU algorithm”), (3) the renormalization scheme connected to the picture change, and (4) a finite nucleus model with a Gaussian charge distribution. The accuracy of NESC energies, which match those of 4-Component Dirac calculations, is demonstrated. Test calculations with CCSD(T), DFT, and large basis sets including high angular momentum basis functions (f,g,h,i) are presented to prove the general applicability of the new NESC algorithm. Comparison with other algorithms of solving the NESC equations are shortly discussed and time savings are presented.