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  [ATENA] Newsletter April 2019
  글쓴이 : 관리자     날짜 : 19-05-01 10:53    
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Newsletter April 2019

Introduction to our spring newsletter 2019

Dear friends of ATENA software,

we hope this newsletter finds you well and busy with interesting and rewarding projects.

Lots of things have changed in our company since the release of our previous newsletter last autumn.

What is the most important, during the past year we hired 4 new engineers/programmers and 3 new part time students, employees to cover the increase in software sales, consulting and research projects. We stay very focused on their thorough completion. On top of it, we invested a huge amount of efforts in our ATENA software development to make it more friendly and robust from the users' perspective.

Since our software starts to be more and more recognized in the world, we decided to take part in many conferences and events worldwide. Please, see the section below for the list of the professional events where you can meet us presenting papers, having a stand or just chatting with you during a conference dinner - what matters is getting closer to you and knowing your current problems.

We look forward to cooperating with you or seeing you somewhere around the globe. The world seems to be surprisingly small sometimes :-).

With best regards from Prague

Your Cervenka Team

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Fig. 1: The display of cuts and internal forces diagrams of cracked concrete structures have been further improved in the new ATENA version

New Release of ATENA Software Version

ATENA version 5.7 is released in June. 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. This process causes the development of expansion strain in concrete, which may cause secondary cracking and can significantly reduce the concrete strength.

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Fig. 2: The analysis of large scale problems is more effective allowing you to model your structures with even more detail.

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Fig. 3: ATENA unique durability models also allow the modelling of chloride ingress and carbonation and their impact on reinforcement corrosion

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.

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Fig. 4: The new feature of tensor or vector plots can be combined with standard ATENA crack display to create beautiful figures providing great insight into the stress flow affected by crack development.

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Fig. 5: The improvements in the post-processing of large scale models is demonstrated on this display of cracking around the containment access hatch.

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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Fig. 6: Principal compressive concrete stresses in the pre-stressed nuclear containment including the base sub-structure was also modeled in the new ATENA version.

ATENA in the cloud

 

ATENA in the cloud. Our new product, the ATENACloud just reached a public BETA version, and 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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Fig. 7: ATENA software can be easily evaluated using our online ATENA cloud application.

ATENA simulation of 3D printing of concrete

The new module for ATENA has been developed to simulate and optimize the printing process and speed. The video shows an example analysis when too fast printing results in the wall collapse.

The printing module shows a procedure of such an analysis on the basis of nonlinear FEM, and it describes all extra features that are needed for such a simulation. These are mainly modelling of the detailed construction process of the structure, time variable load and suitable nonlinear constitutive equations for times ranging from fresh to mature concrete conditions. The newly developed computation modules are implemented into software ATENA (Cervenka et al 2018), which is later also used to compute a few sample analyses. The structure is first modelled at its final size and shape neglecting its construction process. Then, based on the prescribed motion of the printing head, a time for the activation of each element is calculated. The next step is the simulation of the manufacturing process. It is carried out at time steps, whereby at each step at a given time the FE model of the structure consists of active elements only and the rest is ignored.

The printing module is part of an international research project digiCON2, where the presented model will be used to optimize the path and speed of the printing process and for the verification of the structural stability of the printing process as well as of the final structure during its service life.

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Fig. 8: Deformed structure with maximum lateral deformation and the cut with the maximal displacements

ATENA Success Stories

Behaviour of an Armed Concrete Slab and Break Load

Our ATENA software is widely being used in practice in both sectors, commercial and academic. Moreover, we have just received a fresh notification by José Joaquín Ortega and Lucia Garijo from the University of Castilla-La Mancha informing us that they were declared as the winners of the blind prediction competition and obtained the prize using ATENA. For your illustration, we are enclosing two pictures from our Spanish colleagues showing the behaviour of the concrete slab.

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Fig. 9: Damage of the concrete slab

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Fig. 10: CAD-model imported to ATENA

Probabilistic non-linear finite element analysis of concrete buttress dams

Adrian Ulfberg
Master thesis of Science in Civil Engineering at Luleå Tekniska Universitet

What the thesis set out to achieve was to compare analytical calculations in some failure modes to a non-linear finite element analysis and to attempt to quantify the importance of these often disregarded for features. A section of the existing Kalhovd dam in Norway was chosen as a large amount of information about this buttress dam had been gathered. It had also undergone assessment in 2016 (with analytical methods) where this section of the dam had been deemed unstable.

ATENA 2D was the chosen finite element software for the project as it offered a module that allows for probabilistic analysis. This granted the possibility to test structural integrity with varying material parameters simulate material degradation and observe what influence the randomized parameters had on the behavior of the structure.
The results gathered from the deterministic analysis in ATENA showed that the structure was able to withstand the required loads by the Norwegian standards just by adding a more realistic representation of the section’s foundation. Further addition of discrete reinforcement to simulate the present rock bolts improved further upon the stability, well above the called for capacity.

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Fig. 11: Principal minimum strains [-] at final load step (left). Principal (minimum) stresses [MPa] at last load step (right)

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Fig. 12: Load-displacement diagram of probabilistic simulations of model 5

Performing the probabilistic analysis with SARA, with the intent of investigating material parameters and their affect on the structure, the five chosen variables had little impact on the structure with the loads positioned on the structure as stated in the codes, even with very sub-par parameters. It was only when, the position of the force simulating the ice load was lowered closer to the foundation and not at the crest of the dam (as previously modelled), when the material parameters weighed in on the stability.
The reasoning for this is due to the failure mode observed for the structure. It displayed a very dominant overturning failure when including the foundation geometry, whereas for a flat foundation geometry, the structure showed more of a combined sliding and overturning failure.

Results from the study showed that when accounting for the asperities of the foundation, the failure mode of the structure changed. This increased the capacity of the structure massively. The finite element analysis also allowed more than one failure mode to be present/evaluated, whereas impossible for the analytical calculations. The probabilistic analysis showed that the material parameters were of little importance to the overall stability as instability of the structure or loss of function was achieved before any local failures could be obtained.

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Fig. 13: Cracking pattern of simulation 1 at the final load step

The most interesting in this project was found the probabilistic analysis and how it showed clear distinctions between e.g. crack openings of the structure depending on which parameter values the model was given. This led to an understanding of the material parameters impact on the structure, which won’t be revealed in a deterministic analysis.

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 in English language will take place in Prague, the Czech Republic on June 12-14, 2019.


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 in-depth explanation or background information:

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Fig. 14: Come to see Prague in summer and join our ATENA user seminar in June.

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Fig. 15: ATENA seminar 2018.

 

 

  • Overview of new ATENA version 5.7
  • 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

Where You Can Meet Us

April 24-27, 2019
SEI Structures Congress 2019
Orlando, USA
Event website

May 23-24, 2019
Modelling in mechanics 2019
Ostrava, Czech Republic
Event website

May 27-29, 2019
fib Symposium: Innovations in materials, design and structures
Krakow, Poland
Event website

June 3-5, 2019
Underground Construction Prague 2019
Prague, Czech Republic
Event website

June 3-7, 2019
Central European Civil Engineering Meeting
Koszalin, Poland
Event website

June 17-20, 2019
NAFEMS World Congress
Québec City, Canada
Event website

June 24-26, 2019
FramCos-X: Fracture Mechanics of Concrete and Concrete Structures
Bayonne, France
Event website

July 10-12, 2019
NCCE
Udon Thani, Thailand
Event website

August 6-9, 2019
QR2MSE
Zhangjiajie, China
Event website

September 2-4, 2019
The Seventh International Conference on Structural Engineering, Mechanics and Computation
Cape Town, South Africa
Event website

September 17-20, 2019
Fibre Concrete 2019
Prague, Czech Republic
Event website

October 20-24, 2019
ACI Fall
Cincinnati, USA
Event website

November 20-21, 2019
Concrete Days
Hradec Králové, Czech Republic
Event website

Recent Articles

CERVENKA, J., AL-SAUDI A., PRYL, D.: Modelling of High-cycle Fatigue Crack Growth in Concrete, 10th International Conference on Fracture Mechanics of Concrete and Concrete Structures FraMCoS-X, G. Pijaudier-Cabot, P. Grassl and C. La Borderie  (Eds)

CERVENKA, J., CERVENKA, V.: Model Uncertainties and Global Safety Formats for Reinforced Concrete Design by Numerical Simulation, NAFEMS World Congress 2019, June 17-20, Quebec City, Canada, (acknowledgement cyberBridge)

CERVENKA, J., JENDELE, L., VAITOVA, M.: Simulation of digitally printed concrete structures using 3D extrusion, NAFEMS World Congress 2019, June 17-20, Quebec City, Canada (acknowledgement digiCON2)

HULKOVA, G., PUKL, R., CERVENKA, J., SASEK, L.: Tools for back analysis of geotechnical constructions, Undeground Structures, Praha, CR, 2019

JENDELE, L., CERVENKA, J., VAITOVA, M.: FEM modelling of digitally printed concrete structures using 3D extrusion, The Seventh International Conference on Structural Engineering, Mechanics and Computation (SEMC 2019), Sept. 2-4, Cape Town, South Africa (acknowledgement digiCON2)

NOVAK, L., NOVAK, D., PUKL, R.: Probabilistic and semi-probabilistic design of large concrete beams failing in shear (SEMC 2019), Sept. 2-4, Cape Town, South Africa

NOVAK, D., LEHKY, D., PUKL, R.: Fiber-reinforced cementitious composite: Sensitivity analysis and parameters identification, Advanced Material Congress, Miami, USA, December 8-13, 2019

PUKL, R., CERVENKA, V., NOVAK, L., NOVAK, D.: Shear failure of very large concrete beam: Nonlinear, probabilistic and semi-probabilistic modelling, CSM8, Paros, Greece, June 2018

PUKL, R., LEHKY, D., LIPOWCSAN, M., NOVAK, D.: Numerical model and sensitivity analysis for parameter determination of fibre-reinforced concrete, Fibre Concrete Praha, CR, September 17-20, 2019