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Newsletter October 2014

New Release of ATENA Software

ATENA Version 5.1

We are very happy to inform your about the release of this new ATENA version in October 2014. It brings you several very interesting new features in our flagship product ATENA Science, which should enhance your productivity and give you new capabilities and post-processing options that will deepen your understanding of your concrete structures:

The new key features are:

• parallel calculation reduces the analysis time 3-4 times
• improved 3D beam/shell elements for large scale modelling of buildings or bridges
• 3D cut option with the calculation of internal forces: moments, normal and shear forces
• 32 and 64bit versions and new options for nonlinear analysis control
 

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Fig. 1: There is almost 4 times reduction of the analysis time if ATENA is executed on 8 threads

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Fig. 2: Reinforcement stress in multi-storey building using the new shell elements

• shrinkage, creep models based on fib model code 2010 and Eurocode 2
• updated ATENA Studio with unified run-time and post-processing
• unique ATENA crack visualization and animation feature
• Microplane model M7 by Ferhun Caner and Zdenek Bazant
• Contact/Interface modelling with initial opening or moving interfaces

Many of the above features are also available in our standard ATENA 2D and 3D engineering version.

One of the main new features in the new ATENA version is the possibility for parallelization of some computationaly intensive calculations. In ATENA 5.1 a new PARDISO solver can be used to increase the speed of the linear equation solver. Even greater increase in the analysis speed was however obtained by parallelization of the calculation of internal forces.

By the combination of these two approaches the analysis time can be reduced almost 4 times as is documented in the Fig. 1. It shows the analysis time of the standard ATENA tutorial problem, i.e. the Leonhardt shear beam with 20480 3D finite elements and 23528 nodes. The total number of degrees of freedom was 70149, and the analysis was performed up to failure including the post-peak response. This process involved 50 analysis steps with the total number of 165 iterations.

Another strong improvement is the introduction of the new 3D shell elements. These shell elements are also formulated as fully 3D like the former ATENA Ahmad shell elements, but their formulation includes also the normal stress component Sigma_zz. This eliminates the need for the normal displacement constraint, which increases the robustness of these elements in large scale models combining solid and shell elements. Their application is documented in Fig. 2, which shows the nonlinear analysis of a section of a multi-storey apartment building.

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Fig. 3: New 3D cut option with the calculation of internal forces: moments, normal and shear forces

The cut option in ATENA Studio was enhanced by introducing the possibility to integrate the stresses over each cut plane. The integration process automatically considers also any reinforcement bars intersected by the cut plane. This process allows the evaluation of standard engineering quantities such as moments, normal and shear forces (Fig. 3). This feature is present in the standard ATENA 2D Engineering version, and now based on the requests by ATENA users is also available for 3D models.

ATENA Success Stories

Metro Extension in Shanghai – Using ATENA to Reach Cost Optimisation


JKP Static Ltd. based in Hungary analyzed a one-to-one model of the full tunnel section with ATENA at the Tongji Univesity in Shanghai. At JKP ATENA has been used extensively for completion of their worldwide projects for several years. The issue of efficiency, especially time, material and cost savings, is highly demanded nowadays. Most notably, evaluation of these aspects generally contributes to a succesfull project realization.

In the the first stage of this project, the real deflections of the original RC tunnel were modelled and compared. The numerical model showed excellent correlation with the test results, so in the next stage an optimisation process was started, where steel bars were replaced with suitable fibres. The design process was supported by experimental program, and the numerical simulations in ATENA showed very good correlation with the full-scale physical test results. The numerical modelling in ATENA showed that the significant reduction of steel reinforcement by 50 and 75% respectively could be achieved.

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Fig. 4: Principal stress and cracks in ATENA model

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Fig. 5: JKP Static engineers.: Koszely Agnes, Juhasz Karoly Peter, Nagy Lórant

 


Mr. Karoly Peter Juhasz, a chief engineer at JKP Static Ltd., Hungary, summarizes his long-term experience with ATENA software: 

“JKP Static Ltd. - changing the face of engineering through advanced concrete material modelling with ATENA”.

This project was implemented by JKP Static Ltd., Hungary. For more information about their upcoming projects you may click on the following link: www.jkpstatic.com

Experiment at Polytechnique Montréal

ATENA is also a great tool to support experiments. This is the case at Polytechnique Montréal (Canada), where experiments on the mechanical performance of full-scale fibre reinforced concrete (FRC) bridge elements under static and dynamic loading have been conducted for more than a decade. Recently, precast slabs have been tested under bending loads by M.Sc. candidate Frédéric Lachance in order to assess the mechanical behavior of innovative designs using high and ultra-high performance fibre reinforced concrete (HPFRC and UHPFRC) materials.
In this research project, ATENA 3D was used for preliminary design of the experimental setup and for better insight and understanding of the experimental results of the precast slabs.

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Fig. 6: Experimental setup and numerical models for negative bending moment

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Fig. 7: Experimental and numerical negative moment-displacement results

The 3D numerical models used the ATENA Cementitious2 User constitutive law, which was specifically developed for modelling HPFRC and UHPFRC materials. Two FRC precast slabs were modelled. The first one is a hybrid slab design, made of HPFRC with a 30 mm UHPFRC overlay. The second precast slab design is made only of UHPFRC.


3.0 m long and 0.6 m wide precast slab specimens were produced in HPFRC and UHPFRC at a precast plant. They were submitted to four-point bending loads. The results in Fig. 7 show the bending moment in function of the mid-span displacement of the slab under negative bending. One can observe the good correlation between experimental and numerical moment-displacement curves. Cracking patterns and rebar stresses measured in the slabs were also well reproduced with ATENA 3D.

Conferences

We attended two conferences in Canada this summer. The first event held at the University of Québec was focused on PhD students having the opportunity to share information with international research community. Ms. Tereza Sajdlová from our company presented her work there. The abstract is published below, where you can also find the abstract presented at the second event organized by the University of Montreal about fibre reinforced concrete. Mr. Radomír Pukl presented results of his research there.
The latest congress which we attended was 10th CCC 2014, which took place in Liberec, Czech Republic at the beginning of October. Mr. Jan Červenka and Mr. Radomír Pukl participated there with two papers. You can also read the abstracts below.

In case you are interested in receiving the full version of the conference papers, please contact us at cervenka@cervenka.cz
 

10th fib International PhD Symposium in Civil Engineering

Numerical simulations of functionally graded fiber reinforced cementitious composite members

T. Sajdlová, P. Kabele

Functionally graded members are relatively new application of fiber reinforced cementitious composites (FRCC). Numerical modeling using finite element method is a suitable tool for analysis of the behaviour and fracture of FRCC and it can simplify the design of functionally graded members. The main goal of this research is the development of a material model for the analysis of structural elements with non-uniform distribution of fiber reinforcement. The main material properties (e.g. the cohesive law) are determined and implemented into ATENA material models. The results of the numerical simulations are compared with the experimental results. The results of functionally graded FRCC members and homogenous FRCC members are compared, and then the advantages and disadvantages of both groups are discussed.

2nd FRC International Workshop


Optimization of input parameters for material model of fibre reinforced concrete and application on the numerical simulation of tunnel lining

T. Sajdlová, R. Pukl

Nonlinear finite element simulation has a big potential in the field of fibre reinforced (FRC) structures. Special material models accounting for the high toughness and ductility are available for modeling of FRC-material. Input material parameters for the numerical models are here of crucial importance. They are identified from measured response of four-point bending beams using inverse analysis. The optimal material input data sets are utilized for nonlinear modeling of segmental tunnel lining.

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Utilization of steel fibre reinforced concrete (SFRC) for segmental tunnel lining promises potential advantages in comparison to the traditionally reinforced concrete (RC) structures - faster manufacturing, lower risk of corrosion, less damage during transport. Results from the experimental and numerical investigations for RC and SFRC segments are presented. Response of the structural members under service loads and their damage under limit loads are evaluated in order to check and confirm suitability of the SFRC segments for practical utilization.

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10th Central European Congress on Concrete Engineering 2014

Nonlinear analysis of Troja bridge in Prague

J. Červenka, J. L. Vítek, V. Červenka

Nonlinear analysis was used to verify the extent of cracking and crack widths in the end segment of Troja Bridge in Prague. The analysis simulated the whole construction process, and its main objective was to verify the cracking in the massive concrete slabs above the supports at the bridge ends. The nonlinear analysis proved that the cracking would not be extensive, and the crack widths would remain in acceptable limits. This enabled the elimination of additional very short pre-stressing cables in these segments, which reduced the bridge cost as well as simplified the construction process.

Recent tasks and requirements to computer analysis of concrete structures

R. Pukl, T. Sajdlová, J. Mikolášková, P. Havlásek, P. Kabele

In the presented paper, selected applications of nonlinear finite element analysis of existing and designed concrete structures were shown - for transport infrastructure (bridges, tunnels), energetical structures (wind turbine towers), buildings, structural details. Developments of non-linear material models for non-traditional materials (fibre reinforced concrete, ultra high performance concrete, advanced cementitious composites) and actions (fatigue) and their application to computer simulation of structures were discussed including identification of appropriate input parameters. Optimal solution strategies for selected civil engineering problems and methods for an efficient design of modern engineering structures based on the nonlinear computer analysis and global safety concept were proposed.

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ATENA User Seminars 2014

Our both seminars (first in English language, second in Czech language) have taken place in Prague, the Czech Republic and was targeted to ATENA users, who want to learn more about the theoretical background of the ATENA version 5 and its advanced features such as ATENA Studio, GiD-pre-post/processing, dynamic, eigenvalue, creep, thermal or fire analyses.

The new ATENA version 5.1 was used throughout the both seminars. This new version includes a totally reworked runtime and postprocessing environment ATENA Studio that replaces the previous program AtenaWin, and represents the basis for future ATENA development. The main focus will be on the package ATENA Science, which includes an updated GiD interface and new features for parallelization, modeling concrete hydration, seismic and pushover analysis.

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Where You Can Meet Us

October 26-30, 2014
ACI International Convention, Fall 2014
Washington DC, USA
Event website

November 5, 2014
International Shear Force Workshop
Parma, Italy
 

November 25-27, 2014
SMART 2013 workshop
Paris, France
Event website

November 26-27, 2014
Concrete Days 2014
Hradec Králové, ČR
Event website

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Recent Articles

ČERVENKA, J., ČERVENKA, V., PUKL, R., Application of Global Safety Formats from Model Code 2010 for Design and Structural Assesment by Nonlinear Analysis, fib Symposium Mombay 2014, pp. 695-706

ČERVENKA, J., VÍTEK, J., ČERVENKA, V., Nonlinear Analysis of Troja Bridge in Prague, 10th CCC Congress, Liberec 2014

JENDELE, L, ČERVENKA, J., Curvilinear Nonlinear 3D Isoparametric Layered Shell Elements. In: Topping BHV, Iványi P, editors. Twelfth International Conference on Computational Structures Technology Naples, Italy: Civil-Comp Press; 2014

PUKL, R., NOVÁK, D., LEHKÝ, D., (2014): "The Role of Fracture-Mechanical Parameters in Simulating Stochastic Structural Response", CSM7 - Seventh International Conference on Computational Stochastic Mechanics, Santorini, Greece

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