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Battini, J.-M. (2018). Analysis of Dampers for Stay Cables Using Non Linear Beam Elements. Structures, 16, 45-49
Open this publication in new window or tab >>Analysis of Dampers for Stay Cables Using Non Linear Beam Elements
2018 (English)In: Structures, ISSN 2352-0124, Vol. 16, p. 45-49Article in journal (Refereed) Published
Abstract [en]

This paper presents a numerical approach to evaluate the damping properties of a stay cable with an external viscous damper. The idea is to model the cable by using non-linear corotational beam elements and to study small vibrations around the static deformed equilibrium configuration. This gives a complex eigenvalue problem from which the modal damping ratios can be calculated. The performance of the proposed method is assessed through two numerical applications. Compared with the analytical methods based on differential equations widely used in the literature, the proposed non-linear finite element approach has the advantages that the effect of the sag is considered in an accurate way and that there is no limitation regarding the number and the value of the structural parameters that can be introduced in the model. 

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Dampers, Non-linear finite elements, Stay cables
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-236618 (URN)10.1016/j.istruc.2018.08.009 (DOI)000450933400006 ()2-s2.0-85052647926 (Scopus ID)
Note

QC 20181119

Available from: 2018-11-19 Created: 2018-11-19 Last updated: 2018-12-10Bibliographically approved
Chhang, S., Sansour, C., Hjiaj, M. & Battini, J.-M. (2017). An energy-momentum co-rotational formulation for nonlinear dynamics of planar beams. Computers & structures, 187, 50-63
Open this publication in new window or tab >>An energy-momentum co-rotational formulation for nonlinear dynamics of planar beams
2017 (English)In: Computers & structures, ISSN 0045-7949, E-ISSN 1879-2243, Vol. 187, p. 50-63Article in journal (Refereed) Published
Abstract [en]

This article presents an energy-momentum integration scheme for the nonlinear dynamic analysis of planar Euler-Bernoulli beams. The co-rotational approach is adopted to describe the kinematics of the beam and Hermitian functions are used to interpolate the local transverse displacements. In this paper, the same kinematic description is used to derive both the elastic and the inertia terms. The classical midpoint rule is used to integrate the dynamic equations. The central idea, to ensure energy and momenta conservation, is to apply the classical midpoint rule to both the kinematic and the strain quantities. This idea, developed by one of the authors in previous work, is applied here in the context of the co-rotational formulation to the first time. By doing so, we circumvent the nonlinear geometric equations relating the displacement to the strain which is the origin of many numerical difficulties. It is rigorously shown that the proposed method conserves the total energy of the system and, in absence of external loads, the linear and angular momenta remain constant. The accuracy and stability of the proposed algorithm, especially in long term dynamics with a very large number of time steps, is assessed through four numerical examples.

Place, publisher, year, edition, pages
Elsevier Ltd, 2017
Keywords
2D beam, Co-rotational formulation, Conserving energy, Energy-momentum method, Nonlinear dynamic, Dynamics, Kinematics, Momentum, Energy momentum method, Euler Bernoulli beams, Geometric equations, Long term dynamics, Transverse displacements, Nonlinear equations
National Category
Civil Engineering
Identifiers
urn:nbn:se:kth:diva-207289 (URN)10.1016/j.compstruc.2017.03.021 (DOI)000401675600004 ()2-s2.0-85017346411 (Scopus ID)
Note

QC 20170619

Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2018-12-05Bibliographically approved
Chhang, S., Hjiaj, M., Battini, J.-M. & Sansour, C. (2017). An energy-momentum formulation for nonlinear dynamics of planar co-rotating beams. In: COMPDYN 2017 - Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering: . Paper presented at 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2017, Rhodes Island, Greece, 15 June 2017 through 17 June 2017 (pp. 3682-3696). National Technical University of Athens, 2
Open this publication in new window or tab >>An energy-momentum formulation for nonlinear dynamics of planar co-rotating beams
2017 (English)In: COMPDYN 2017 - Proceedings of the 6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, National Technical University of Athens , 2017, Vol. 2, p. 3682-3696Conference paper, Published paper (Refereed)
Abstract [en]

This article presents an energy-momentum integration scheme for the nonlinear dynamic analysis of planar Bernoulli/Timoshenko beams. The co-rotational approach is adopted to describe the kinematics of the beam and Hermitian functions are used to interpolate the local transverse displacements. In this paper, the same kinematic description is used to derive both the elastic and the inertia terms. The classical midpoint rule is used to integrate the dynamic equations. The central idea, to ensure energy and momenta conservation, is to apply the classical midpoint rule to both the kinematic and the strain quantities. This idea, developed by one of the authors in previous work, is applied here in the context of the co-rotational formulation to the first time. By doing so, we circumvent the nonlinear geometric equations relating the displacement to the strain which is the origin of many numerical difficulties. It can be rigorously shown that the proposed method conserves the total energy of the system and, in absence of external loads, the linear and angular momenta remain constant. The accuracy and stability of the proposed algorithm, especially in long term dynamics with a very large number of time steps, is assessed through two numerical examples.

Place, publisher, year, edition, pages
National Technical University of Athens, 2017
Keywords
2D beams, Conserving energy, Corotational formulation, Energy-momentum method, Nonlinear dynamic
National Category
Other Engineering and Technologies
Identifiers
urn:nbn:se:kth:diva-224408 (URN)2-s2.0-85042298112 (Scopus ID)9786188284425 (ISBN)
Conference
6th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, COMPDYN 2017, Rhodes Island, Greece, 15 June 2017 through 17 June 2017
Note

QC 20180316

Available from: 2018-03-16 Created: 2018-03-16 Last updated: 2018-03-16Bibliographically approved
Heng, P., Hjiaj, M., Battini, J.-M. & Limam, A. (2017). An enhanced SDOF model to predit the behaviour of a steel column impacted by a rigid body. Engineering structures, 152, 771-789
Open this publication in new window or tab >>An enhanced SDOF model to predit the behaviour of a steel column impacted by a rigid body
2017 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 152, p. 771-789Article in journal (Refereed) Published
Abstract [en]

The transient dynamic response of a steel beam-column subjected to impact loading is a complex phenomenon involving large localized plastic deformations and non-smooth contact interactions. Exposed to high intensity of the contact force generated from impact, the beam-column may undergo large displacement and inelastic deformation. Previous research has shown that a calibrated elasto-plastic single degree of freedom system is able to reproduce both the displacement and the force time-history of a steel beam subjected to non-impulsive loading or low-velocity impact. In these models, the static force-displacement curve is derived from either experiments or detailed 3D nonlinear analysis. Tri-linear resistance function has been extensively used to reproduce the different stages of the response including catenary effects. A rigorous treatment of such a complex problem calls for the use of non-smooth analysis tools to handle the impulsive nature of the impact force, the unilateral constraint, the impenetrability condition and the discontinuity of the velocity in a rigorous manner. In this paper, we present a non-smooth elasto-plastic single degree of freedom model under impact loading that permits the use of arbitrary resistance function. Adopting the non-smooth framework offers tools such as differential measures and convex analysis concepts to deal with unilateral contact incorporating Newton’s impact law. The mid-point scheme is adopted to avoid numerical unrealistic energy decay or blowup. Furthermore, the non-penetration condition is numerically satisfied by imposing the constraint at only the velocity level to guarantee energy-momentum conservation [1]. The explicit expression of resistance functions of the beam that are used in the SDOF model are obtained from a simplified nonlinear static analysis of two beam-column models. In the analysis, a linear relation between normal force and bending moment is assumed for the plastification of the hinges. Two proposals to simplify the explicit expressions of the model’s response behavior are given. Performing an energy-based analysis, we predict maximum displacement that is needed to absorb the kinetic energy arising from the impact for different coefficient of restitution. The numerical examples underline the validity of the model by showing good agreement with the predictions of reference models.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Single degree of freedom, Impact, Non-smooth analysis, Steel structures, Catenary action, Analytical solution
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-217277 (URN)10.1016/j.engstruct.2017.08.061 (DOI)2-s2.0-85042169401 (Scopus ID)
Note

QC 20171106

Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2018-02-27Bibliographically approved
Heng, P., Alhasawi, A., Battini, J.-M. & Hjiaj, M. (2017). Co-rotating rigid beam with generalized plastic hinges for the nonlinear dynamic analysis of planar framed structures subjected to impact loading. Finite elements in analysis and design (Print)
Open this publication in new window or tab >>Co-rotating rigid beam with generalized plastic hinges for the nonlinear dynamic analysis of planar framed structures subjected to impact loading
2017 (English)In: Finite elements in analysis and design (Print), ISSN 0168-874X, E-ISSN 1872-6925Article in journal (Refereed) Submitted
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-217279 (URN)
Note

QC 20171106

Available from: 2017-11-06 Created: 2017-11-06 Last updated: 2017-11-06Bibliographically approved
Liu, F., Battini, J.-M., Pacoste, C. & Granberg, A. (2017). Experimental and Numerical Dynamic Analyses of Hollow Core Concrete Floors. Structures, 12, 286-297
Open this publication in new window or tab >>Experimental and Numerical Dynamic Analyses of Hollow Core Concrete Floors
2017 (English)In: Structures, ISSN 2352-0124, Vol. 12, p. 286-297Article in journal (Refereed) Published
Abstract [en]

Due to their low self-weight and high strength, precast and prestressed hollow core concrete slabs are widely used in construction. However, the combination of low self-weight and long span implies that the slabs are sensitive to vibrations induced by human activities. In this work, experimental tests and numerical analyses are performed in order to understand the dynamic behaviour of hollow core concrete floors. For the experiments, a test floor of dimension 10 m × 7.2 m and consisting of 6 hollow core elements was built. Very good agreements between experimental and numerical results have been obtained. Comprehensive numerical parametric analyses have been performed in order to determine the optimal value of the material parameters.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Dynamic analyses, Experimental tests, Finite element model, Hollow core concrete slabs, Model calibration
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-218309 (URN)10.1016/j.istruc.2017.10.001 (DOI)000418536400023 ()2-s2.0-85033669374 (Scopus ID)
Note

QC 20171127

Available from: 2017-11-27 Created: 2017-11-27 Last updated: 2018-03-23Bibliographically approved
Lind Östlund, J., Andersson, A., Mahir, Ü.-K. & Battini, J.-M. (2017). Soil-Structure Interaction for foundations on High-Speed Railway Bridges. Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Soil-Structure Interaction for foundations on High-Speed Railway Bridges
2017 (English)Report (Other academic)
Abstract [en]

This report contains a parametric study on the dynamic response of railway bridges on flexible supports. The results are based on simulations using 2D and 3D models. The dynamic stiffness of the supports is described by separate models of the foundation, including relevant stress and strain dependent soil properties from permanent loading that is linearized in a subsequent dynamic analysis. The complex-valued dynamic stiffness constitutes the boundary conditions in a separate analysis of the bridge superstructure that is solved in frequency domain.

Two different foundation types are studied; shallow slab foundation with relatively good ground conditions, and pile group foundations with relatively poor ground conditions. In both cases, the foundation slab and the pile group have fixed geometry. In the parametric study, the corresponding vertical static foundation stiffness range from 2 – 20 GN/m for the slab foundation and 5 – 25 GN/m for the pile group foundation.

For the slab foundations, both the stiffness and damping highly depends on the properties of the soil, foundation depth and geometry of the foundation slab. For the pile group foundations, the stiffness is mainly governed by the pile group and the damping by the soil.

Based on the simulations, the additional damping from the slab foundation is in most cases negligible. Only for relatively soft foundations and short-span bridges significant additional damping is seen. For the pile group foundations, the additional damping is in some cases significant, especially for deeper foundations and short-span bridges. Considering a lower bound of the parametric study does however result in a negligible contribution.

The dynamic response from passing trains show that the assumption of fixed supports in most cases is conservative. However, the flexible supports may result in a lower natural frequency that should be accounted for in order to not underestimate the resonance speed of the train.

If flexible supports are included in a dynamic analysis, both the stiffness and damping component needs to be included. The frequency-domain approach presented in this report is a viable solution technique but is not implemented in most commercial software used in the industry.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. p. 65
Series
TRITA-BKN, ISSN 1103-4289 ; 166
Keywords
Dynamic soil-structure interaction; impedance; foundation stiffness; railway bridge; high-speed trains
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-230757 (URN)
Funder
Swedish Transport Administration, TRV 2016/56775
Note

QC 20180618

Available from: 2018-06-15 Created: 2018-06-15 Last updated: 2018-06-18Bibliographically approved
Heng, P., Hjiaj, M., Battini, J.-M. & Limam, A. (2016). A simplified model for nonlinear dynamic analysis of steel column subjected to impact. International Journal of Non-Linear Mechanics, 86, 37-54
Open this publication in new window or tab >>A simplified model for nonlinear dynamic analysis of steel column subjected to impact
2016 (English)In: International Journal of Non-Linear Mechanics, ISSN 0020-7462, E-ISSN 1878-5638, Vol. 86, p. 37-54Article in journal (Refereed) Published
Abstract [en]

This paper presents a new simplified model of the nonlinear dynamic behavior of a steel column subjected to impact loading. In this model, the impacted column, which undergoes large displacement, consists of two rigid bars connected by generalized elastic–plastic hinges where the deformation of the entire steel column as well as the connections is concentrated. The effect of the rest of the structure on the column is modeled by an elastic spring and a point masse both attached to the top end of the column which is also loaded by a compressive force. The plastification of the hinges follows the normality rule with a yield surface that accounts for the interaction between M and N. The latter is described by a super-elliptic yield surface that allows ones to consider a wide range of convex yield criterion by simply varying the roundness factor that affects the shape of the limit surface. By including these features, the model captures both geometry and material nonlinearities. Both the flow rule and the equations of motion are integrated using the midpoint scheme that conserves energy. The non-smooth nature of impact is considered by writing the equations of motion of colliding masses using differential measures. Contact conditions are written in terms of velocity and combined with Newton's law to provide the constitutive law describing interactions between masses during impact. Numerical applications show that the model is able to capture the behavior of a column subjected to impact.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Catenary action, Energy-conserving scheme, Generalized plastic hinges, Impact, Non-smooth mechanics, Progressive collapse, Steel structures, Control nonlinearities, Dynamic analysis, Hinges, Steel construction, Structural dynamics, Catenary actions, Energy-conserving, Plastic hinges, Equations of motion
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-195223 (URN)10.1016/j.ijnonlinmec.2016.07.005 (DOI)000386405200007 ()2-s2.0-84982145085 (Scopus ID)
Note

QC 20161117

Available from: 2016-11-17 Created: 2016-11-02 Last updated: 2017-11-29Bibliographically approved
Le, T.-N., Battini, J.-M. & Hjiaj, M. (2015). A new 3D co-rotational beam element for nonlinear dynamic analysis. In: COMPDYN 2015: . Paper presented at 5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, Creta Greece, 2015 (pp. 1087-1110).
Open this publication in new window or tab >>A new 3D co-rotational beam element for nonlinear dynamic analysis
2015 (English)In: COMPDYN 2015, 2015, p. 1087-1110Conference paper, Published paper (Refereed)
Abstract [en]

The paper investigates the contribution of the warping deformations and the shear center location on the dynamic response of 3D thin-walled beams obtained with an original consistent co-rotational formulation developed by the authors. Consistency of the formulation is ensured by employing the same kinematic assumptions to derive both the static and dynamic terms. Hence, the element has seven degrees of freedom at each node and cubic shape functions are used to interpolate local transversal displacements and axial rotations. Accounting for warping deformations and the position of the shear center produces additional terms in the expressions of the inertia force vector and the tangent dynamic matrix. The performance of the present formulation is assessed by comparing its predictions against 3D-solid FE solutions.

Keywords
Computational methods; Deformation; Degrees of freedom (mechanics); Dynamics; Engineering geology; Geophysics; Structural dynamics; Thin walled structures, Co-rotational formulation; Earthquake engineering; ECCOMAS thematic conference; Instructions; Kinematic assumptions; Proceedings; Transversal displacement; Warping deformations, Earthquakes
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-174734 (URN)2-s2.0-84942284213 (Scopus ID)
Conference
5th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering, Creta Greece, 2015
Note

QC 20151105

Available from: 2015-11-04 Created: 2015-10-07 Last updated: 2015-11-04Bibliographically approved
Bornet, L., Andersson, A., Zwolski, J. & Battini, J.-M. (2015). Influence of the ballasted track on the dynamic properties of a truss railway bridge. Structure and Infrastructure Engineering, 11(6), 796-803
Open this publication in new window or tab >>Influence of the ballasted track on the dynamic properties of a truss railway bridge
2015 (English)In: Structure and Infrastructure Engineering, ISSN 1573-2479, E-ISSN 1744-8980, Vol. 11, no 6, p. 796-803Article in journal (Refereed) Published
Abstract [en]

This article presents numerical and experimental analyses of a steel truss railway bridge. The main interest of this work is that dynamic experiments have been performed before and after the ballasted track was placed on the bridge. Consequently, it has been possible to quantify the effect of the ballast and the rails on the dynamic properties of the bridge. For that, two finite element models, with and without the ballasted track, have been implemented and calibrated using the experimental results. It appears that the ballast gives an additional stiffness of about 25-30% for the lowest three eigenmodes. This additional stiffness can be only partly explained by the stiffness of the ballast. In fact, it seems that this additional stiffness is also due to a change of the support conditions.

Keywords
Ballast, Railway bridges, Experimental dynamics, Finite element modelling
National Category
Infrastructure Engineering
Research subject
Civil and Architectural Engineering
Identifiers
urn:nbn:se:kth:diva-142825 (URN)10.1080/15732479.2014.912242 (DOI)000349904000005 ()2-s2.0-84924222475 (Scopus ID)
Note

Updated from accepted to published.

QC 20150325

Available from: 2014-03-12 Created: 2014-03-12 Last updated: 2017-12-05Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2104-382X

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