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Newsletter October 2018

Dear friends of ATENA software,
 
we hope you are doing well and this year will be successfull for you.

As the year is slowly coming to its end, we suppose you are fully busy with finishing your interesting projects on schedule. We would like to bring your kind attention towards the latest development in our ATENA software, which we strive to continuously develop in order to bring the latest achievements in the numerical modeling of reinforced concrete to your desk.

We would also like share our success stories with you because they are written by our users. By knowing their own ATENA experience, we can analyze what we have done well and what should be improved. To meet our users' needs, we regularly organize our ATENA seminar for our users to get familiar with our software's capabilities.

We wish you pleasant reading and we look forward to introducing you any further improvements in ATENA in the upcoming year. 


With kind regards from Prague
Your Cervenka team

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Improved visualization of vectors and tensorial quantities in ATENA supports new options for user adjustments so that beautiful as well as instructive figures can be created to show for instance the stress flow inside the structure.

New Release of ATENA Software Version

ATENA version 5.7 will be released this fall. It contains important improvements to the various features introduced in the previous years. These improvements were triggered by the feedback of our users and clients.

Better performance in solving and post-processing large scale analysis

ATENA software is becoming the premier solution for checking the design or assessment of large and safety critical structures. It is therefore often useful to develop large scale complex models involving various element types: - 1D/3D beam elements – 2D/3D shell elements – 2D/3D solid elements. ATENA supports standard 1D beam and 2D shell elements. In addition, it includes special 3D beam as well as shell elements, with only displacement degrees of freedom. This simplifies the development of complex large scale models, where it is useful to combine beam and shell elements with solid elements. Beam and shell elements can be effectively used in areas with dominantly bending behavior, while critical shear dominated areas can be modeled by solid elements. Based on the feedback of ATENA users as well as our own experience of using ATENA in large scale analysis of tall buildings, we have improved the speed of analysis and namely postprocessing almost 100 times compared to version 5.6. Such large models are demonstrated in the figures in this newsletter, which shows results from performance based design of a multistorey buildings supported by nonlinear analysis.

Durability modeling - new model for Alkali-silica-reaction in concrete
Alkali-silica reaction (ASR) is a reaction in concrete between alkali hydroxides and reactive siliceous aggregates.

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Results from a pushover analysis of a reinforced concrete building, top - deformed shape and crack pattern, bottom - stresses in the main reinforcement.

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ATENA modeling of pushover analysis of a high rise building. Left bottom window shows calculated crack widths and crack pattern. Right window shows the deformed shape with the principal compressive stress in concrete.

This process causes the development of expansion strain in concrete, which may cause secondary cracking and can significantly reduce the concrete strength. This new material is part of our ongoing effort to provide engineers with an efficient tool to evaluate the durability of reinforced concrete structures. ATENA models now cover the most important aspects of durability of reinforced concrete structures such as chloride and carbonation process, reinforcement corrosion and ASR. The durability features are all available now in the new version 5.7, and they have been developed during a research project DURACERV funded by Czech Technological Agency under the project #TA04031458.

Improvements in the run-time and post-processor program ATENA Studio
ATENA Studio has by now become the most popular software in the ATENA simulation system. It allows runtime visualization of the analysis process as well as full post-processing capabilities even while the analysis is still running and the iterative process is not yet completed.

 

This very useful insight into the iterative process helps to discover any modeling errors and gives useful hints how to eliminate any divergence problems. This program has been further improved in the version 5.7.

The main improvements are:
-    faster post-processing of large scale models, speed increase almost 100 times
-    new display of local element coordinate systems, especially useful for beam and shell elements
-    new colored display of tensorial quantities such as principal stresses and strains
-    new colored display of vector quantities of forces and displacements
-    improvements in the visualization and definition of moment, normal and shear force diagrams and 1D evolution graphs of beam and reinforcement quantities
-    plus many other minor improvements and corrections

Other new features and improvements:
The latest version of Microplane M7 model from Prof. Zdenek Bazant and Prof. Ferhun Caner has been implemented to improve the behavior of M7 material model for the modeling of brittle materials such as concrete, rock or masonry.
Improvements in the tensile fatigue model that enables to consider the fatigue damage in concrete material in high cycle fatigue.

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Photo: Tata Consultancy Services Campus Chennai, below ATENA analysis of the RC slab on top of the campus tower.

Virtual Testing Laboratory Service

 

ATENA in the cloud. Our new product, the Virtual Testing Laboratory Service, just reached a public BETA version. We would like to invite you to try it.

http://vtls.cervenka.cz/

VTLS allows you to use our software ATENA and other tools on cloud based computers. These are created instantly, with all needed software pre-installed.

Data can be uploaded/downloaded via this web application. To connect cloud computers created via VTLS you will need some RDP client software. Computers can be operated from any operating systems including mobile platforms iOS and Android.

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ATENA Success Stories

Nonlinear FE analysis for concrete hinges

Nonlinear FE analysis for concrete hinges
[Kalliauer2018ActaMechanica, Kalliauer2018EuroC]

Concrete Hinges (Fig.1) are used in Bridge columns and in Tunnel linings. In the last years concrete hinges gained an increasing interest in monolithic construction, because they are economic, durable and ecological. Current design standards for concrete hinges are based on the guidelines of Leonhardt and Reimann. Nowadays design standards require a semiprobabilistic safety-concept for the Service-Limit-States as well as for the Ultimate-Limit-States. Leonhardt’s guidelines focus more on the Service-Limit-States, and therefore TU-Wien tested several concrete hinges up to their bearing capacity to derive new, substantive design standards. The Institute for Mechanics of Materials and Structures used an external micro-mechanical approach developed by Hlobil et al. for editing the input parameters. ATENA Science is used to model concrete under high triaxial compression [Kalliauer2018ActaMechanica] using the Menétrey-William-failure-surface, which was later improved by Červenka.

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Fig.1: Experiments at TU-Wien.

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Fig.2: Stresses all three directions (left: loading direction, middle: horizontal direction, right: thickness direction).

A stress ratio of approximately 1:0.5:0.3 (Fig. 2) occurs on the compressive side of the hinge [Kalliauer2018ActaMechanica], leading to a compressive strength of two times the uniaxial compressive strength [Kalliauer2018ActaMechanica].  Also this triaxial stress path leads to a glancing intersection with the failure-meridian [Kalliauer2018ActaMechanica], ATENA Studio can predict the bearing capacity within the experimental scattering without any fitting parameters.

The Master thesis of Kalliauer includes a more detailed analysis, such as (a) parameter identification (Fig.3), including the influence on stresses and strains as well as on the bearing capacity, (b) convergence studies, including mesh dependency, (c) influence on different material models, (d) stress distributions in the cross section, (e) dependency of front-side-notches and (f) a statistical sensitivity Analyses carried out in SARA Studio (Fig. 4).

The Institute for Mechanics of Materials and Structures want to thank the ATENA hotline support for having answered all the questions.

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Fig.3: Dependence of the fracture Energy an the plastic strains (left: low fracture energy; right: high fracture energy).

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Fig.4: Stochastic Analysis in Sara Studio for the bearing capacity.

[Kalliauer2018ActaMechanica] KALLIAUER, J., SCHLAPPAL, T., VILL, M., MANG, H. & PICHLER, B.: Bearing capacity of concrete hinges subjected to eccentric compression: multiscale structural analysis of experiments; Acta Mechanica, Springer Nature, 2018; pp.849-866, DOI: 10.1007/s00707-017-2004-3

[Kalliauer2018EuroC] KALLIAUER, J., SCHLAPPAL, T., MANG, H. A. & PICHLER, B. (Ed.: MESCHKE, G., PICHLER, B. & ROTS, J. G.): Parameter identification as the basis for Finite Element simulations of Ultimate Limit States of concrete hinges; Proceedings Euro-C 2018 conference, ISBN 978-1-138-74117-1, Feb. 2018, pp. 689
 

ATENA Advanced User Seminar 2019

 

Dear users of ATENA software,


we would like to invite you to our ATENA Advanced User Seminar 2019. The seminar will take place in Prague, the Czech Republic on February 20-22 in Czech language and June 12-14, 2019 in English language.


In 2016 the content of the seminar was rearranged compared to the previous years. We decided to concentrate on fewer topics, but provide deeper coverage and more hands-on experience with particular problems. Based on the feedback from our hotline support, we selected several topics, where we expect that ATENA users could benefit most from more indepth explanation or background information:
 

  • Overview of new ATENA version 5.6.
  • Modeling contact problems in ATENA.
  • Modeling strengthening of reinforced concrete structures.
  • Modeling of construction process in ATENA for bridges and tunnels.
  • Modeling of fiber-reinforced concrete structures.
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Where You Can Meet Us

October 7-11, 2018
fib Congress 2018
Melbourne, Australia
Event website

October 14-18, 2018
ACI Fall 2018
Las Vegas, USA
Event website

November 6-9, 2018
MECOM 2018
Tucumán, Argentina
Event website

November 21-22, 2018
Concrete Days 2018
Prague, Czech Republic
Event website

Recent Articles

Al-Saoudi, A., Al-Mahaidi, R., Kalfat, R., Cervenka, J.: Finite Element Investigation of the Fatigue Performance of FRP Laminates Bonded to Concrete, Composite Structures, Volume 208, 15 January 2019, Pages 322-337, https://doi.org/10.1016/j.compstruct.2018.10.001

CERVENKA, J., CERVENKA, V., LASERNA. S.: On Crack Band Model in Finite Element Analysis of Concrete Fracture in Engineering Practice, Engineering Fracture Mechanics, Volume 197, 2018, Pages 27-47, ISSN 0013-7944.
http://www.sciencedirect.com/science/article/pii/S0013794418301620

CERVENKA, J., CERVENKA, V., SYKORA, M., MLCOCH, J.: Evaluation of Safety Formats for Structural Assessment Based on Nonlinear Analysis, Proceedings Euro-C 2018 conference, ISBN 978-1-138-74117-1, Feb. 2018, pp. 669-678

CERVENKA, V., CERVENKA, J, KADLEC, L.: Model Uncertainties in Numerical Simulations of Reinforced Concrete Structures - Structural Concrete Journal fib, Journal of International Federation for Structural Concrete. DOI: 10.1002/suco.201700287, 2018;1–13

DIAS-DA-COSTA, D., CERVENKA, V., GRACA-E-COSTA, R.: Model Uncertainty in Discrete and Smeared Crack Prediction in RC Beams under Flexural Loads. Engineering Fracture Mechanics. 199 (2018) 532-543

HAJKOVA, K., SMILAUER, K., JENDELE, L., CERVENKA, J.: Prediction of Reinforcement Corrosion due to Chloride Ingress and its Effects on Serviceability, Engineering Structures 174 (2018), pp. 768-777

KUKLIK, P., SUSANTI, E., VALEK, M., NOVAK, D., PUKL, R.: Bearing Capacity of Masonry Walls in Churches - Numerical Investigation, 11th International Conference on Structural Analysis of Historical Constructions "An interdisciplinary approach", Cusco, Peru, September 2018

PUKL, R., CERVENKA, V.: Uncertainty Aspects in Fracture-Mechanical Analysis of Concrete Structures, 16th International Probabilistic Workshop (IPW2018), Vienna, Austria, September 2018

PUKL, R., CERVENKA, V., NOVAK, D.: Shear Failure of Very Large Concrete Beam: Modelling using Random Fields, CSM8 - 8th Conference on Computational Stochastic Mechanics, Paros, Greece, June 2018

PUKL, R., LEHKY, D., NOVAK, D.: Towards Nonlinear Reliability Assessment of Concrete Transport Structures, IABSE Conference "Engineering the Developing World", Kuala Lumpur, Malaysia, April 2018

PUKL, R., SAJDLOVA, T., CERVENKA, J.: Design of SFRC Precast Tunnel Segments Supported by NLFEA, 3rd FRC ACI-fib-RILEM Joint International Workshop "Fibre Reinforced Concrete: from Design to Structural Applications", Desenzano, Italy, June 2018

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