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Newsletter October 2020

We are Making our Breakthrough with new ATENA 5.7

Dear ATENA fans, friends and followers,

We are very pleased to announce the release of brand new ATENA 5.7. which represents a milestone in our latest development. 

We managed to bring some new features to your desktop that we think are worth evaluating. 

They will be described in more detail below, however, we are picking up just a summary of them to give you a first hint of how useful it might be for your daily work:

- reinforcement corrosion
- alkali-silica reaction (ASR)
- significant speed increase while running analysis
- durability modelling enhancements

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Fig. 1: Pre-stressed concrete bridge with segmental construction process recently analysed by ATENA.

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Fig. 2: View of the numerical model of one cantilevered section of the segmenta bridge, (top) deformed shape at the end of bridge construction.

You can evaluate these major improvements either by renewing your maintenance contract in case you are our existing customer, or alternatively, if you are new to ATENA please contact us about the licensing options available for your.

We believe this will convince you to start working with ATENA 5.7. and make use of its capabilities.  

Additionally, we are currently completing the implementation of a support for 3D printing of concrete. This enhancement is highly demanded nowadays (see our project digiCON2 for more details) and should be part of the newly prepared ATENA 5.8, which is expected to be released in the beginning of next year. Of course, you will be notified about its release. If you are interested in testing this new feature, please contact us and we will provide you with our beta version.

We look forward to responding to your queries about ATENA 5.7. 

With warm regards and wishes of good health,

Your Cervenka Team

New Features in the Latest Versions of ATENA Software

In October the latest version ATENA v5.7 has been released and is available for download from our website.

The speed of nonlinear analysis has been significantly improved as well as the speed of post-processing large models.
In addition several unique new features has been introduced:

- Modeling of durability and corrosion - chloride ingress and concrete carbonation in the concrete cover is simulated taking into account the presence of cracks. This induces reinforcement corrosion, which is modelled as a reduction of reinforcement cross-section having an impact on the structural load carrying capacity.


- Simulation of concrete deterioration due to alkali-silica reaction (ASR)
- New model for fibre-reinforced concrete (FRC) based on added fracture energy concept
- Streamlined definition for combined models consisting of advanced models with solid elements and 1D beam or 2D shell elements
- Material driver – a small software for testing and detailed investigation of ATENA material models or for the development of material user subroutines

For more details about the latest ATENA version please see our website.

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Fig. 3: Concrete cracking above the main support, moment evolution and deflection of a composite steel-concrete bridge analyzed by ATENA.

ATENA Success Stories

Reinforcement Layout in Concrete Pile Foundations


This interesting study was completed at KTH University, Sweden and supported by Tyréns company. The author is Mustafa Angar, and he studied the behavior of concrete pile cap supported by four piles with two varying positions of longitudinal reinforcements.
The positions include top of piles and bottom of the pile cap. For this purpose, non-linear finite element models of a pile cap were created using software ATENA.
The objective was to investigate which position of reinforcement yields the higher bearing capacity and to study the failure modes in the models.

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Fig.4: Results of the mesh sensitivity study in the pile cap analysis.

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Fig. 5: Effect of fracture energy on the obtained crack patterns in pile cap analysis.

The numerical analysis started by creating four pile cap models in ATENA 3D. The difference between the models being the position and ratio of longitudinal reinforcement.
The purpose behind the two reinforcement ratios was to observe the behavior of pile cap model in two cases: a) when failure occurs prior to yielding of reinforcement; b) when failure occurs after reinforcement is yielding. The models were then analyzed using software ATENA Studio, which can more efficently exploit the improvements in ATENA analysis speed and parallelization.
A parametric study was performed in the model as well to investigate the effects of various parameters on the results obtained. It was found that fracture energy had the most significant effect on the results obtained.
The results revealed that placing the reinforcement on top of the piles in case (a) increased the capacity of the model by 23.5 % and in case (b) (pile cap bottom) increased the capacity by 18.5 %. This because the tensile stresses were found to be concentrated on top of piles rather than at the bottom of pile caps.


The final failure mode in the model with top reinforcement position was crushing of the inclined compressive strut beneath the column, and in the model with bottom reinforcement position, the splitting of the compressive strut due to tensile stresses developed perpendicular to the inclined strut.

The potential advantage of placing the reinforcement at the pile cap bottom was better crack control in serviceability limit state and a slightly less fragile failure mode compared to the pile top position of reinforcement.

The complete publication is available for download here.

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Fig. 6: Typical example of a reinforced concrete pile cap.

Punching Shear in Concrete Flat Slabs Supported on Slender Edge Steel Columns

Jose Andres Perez and Pasha Jalal completed their Master thesis at KTH, and ATENA was used for the modelling of punching shear in reinforced concrete slabs.

Non-linear finite element analyses (NLFEA) has been used to study the cracking and failure mechanism of a reinforced concrete slab. It is a slab over the edge support without clamping stiffness, therefore simulating the slab shear mechanism over a slender steel column was carried out in this thesis.
The analyses has been performed using the software ATENA. Since the symmetry has been taken into account over the edge column, only one half of the cross-section has been modeled, with a symmetry line passing vertically through the slab and the column.

It can be summarized that the failure occurred in the vicinity of the column, and has a conical shape crack pattern similar to the ones encountered when punching shear occurs. However, it is important to note that this failure is not due to classical punching shear, but instead due to shear cracks developing around the column in both directions, both parallel and perpendicular to the free-edge.

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Fig. 7: Deformed model at failure.

Three models were studied to evaluate the impact of the length of the lower leg of the c-bar reinforcement. The crack propagation during punching shear begins from the upper surface of the slab and prolongs downwards diagonally towards the bottom of the slab that is adjacent to the column.
However, the crack propagation in the strip perpendicular to the free edge in all three models initiate from the bottom and propagate upwards.


It can be concluded that the length reduction of the lower leg of the c-bars reduces the shear strength capacity of the slab around the steel-plate. The reason for this is due to a reduction in maximum peak load when the lower leg of the c-bars were reduced. Consequently, this leads to a decrease in shear strength capacity of the slab and an earlier failure, where the inner-span was not able to take additional loads which could have led to greater deflections.

The complete publication is available for download here.

 

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Fig. 8: Reinforcement stress at failure, c-bar reinforcement along the right bottom edge.

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Fig. 9: Three-point bending tensile test for dosing 75* kg/m3.

Determination of Mechanical Properties of Fiber Reinforced Concrete for Numerical Modelling


MARCALIKOVA, Z, CAJKA, R., Department of Structures, Faculty of Civil Engineering, VSB-Technical University of Ostrava, Ludvíka Podéště 1875/17, 708 33 Ostrava-Poruba, Czech Republic.

The study deals with the determination of mechanical properties of fiber reinforced concrete in dependence on various dosages and recipe of concrete. The mechanical properties were determined for the default recipe of concrete, where the individual variants differ in the amount of fibers. In the experimental program: compressive strength, modulus of elasticity, split tensile strength, flexural tensile strength and load-displacement diagram were investigated.

The flexural tensile strength was determined based on a three-point and four-point bending test. Based on the evaluated data, the uniaxial tensile strength was evaluated and the functional dependence on the resultant recipe of concrete with a dosage of 75 kg/m3 is with respect of the increasing importance and application of numerical modelling of building structures was investigated. The analyses performed using non-linear calculation using software ATENA. The aim was to simulate the performed laboratory test and appropriately approximate the specific input parameters of the fiber reinforced concrete model for the nonlinear analysis.

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Fig. 10: Normal stress σx - displacement 8 mm.

The research dealt with the determination of mechanical properties of fiber reinforce concrete for various dosages of fibers in concrete. Specifically, they were fibers Dramix® 3D 65/60 BG with end bends. Dose fibers was 0, 25, 50, 75 kg/m3. For a dosage 75 kg/m3, it has been found that a recipe needs to be adjusted to increase / improve mechanical properties. In some cases, the recipe change has improved the tensile properties by 44%. The resulting mechanical properties determined based on of laboratory tests are important for numerical modelling, but need to be supplemented with specific parameters as presented for the selected case. Numerical modelling then makes it possible to describe the gradual development of a crack very well and thus to optimize the structural design, e.g. industrial floors, foundation slabs in interaction with the subsoil, etc.

Research and Development Projects

Completed Projects

cyberBridge

We have completed the International Research and development project cyberBridge from Eurostars program this year. Within this project new approaches for combining bridge monitoring with advanced nonlinear modelling were developed.
Three bridges in Czech Republic, Germany and Austria have been monitored. The numerical model was calibrated using the real traffic as shown on the video here. The calibrated model was used to make long term assessment and prognosis of the bridge reliability.

More information you can find on http://www.cyberbridge.eu/

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Fig. 11: Summary of the main achievements in the service life evaluation of a bridge in Esslingen, Germany.

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Fig. 12: The symmetric quarter model of concrete container for disposal of VVER-440 type spent nuclear fuel and contour plots from its thermal analysis.

New Projects Started in 2020

 

Development of Coupling Details for Concrete Containers for Radwaste and Spent Fuel and Modeling of Their Long-Term Performance

Partners: CTU Prague, Cervenka Consulting, s.r.o., Stavby - Kominy, s.r.o., Centrum vyzkumu Rez, s.r.o.

The project deals with the design of limit parameters (volume of container and used concrete) of multi-barrier containers for high-level waste and spent fuel disposal. The design takes into account the volume of released gases due to gamma-radiation and thermal load and subsequent container pressure increase.

 

The ultimate goals are:

1. Development of software for container pressure and limit parameters calculation affected by the volume of released gases depending on the water-to-cement ratio of concrete mixture. The input parameters will be obtained by experimental investigation of weight loss of concrete samples during gamma irradiation and heat load.
2. Production of functional designs of fresh concrete mixture and reinforcement of the container using anchors in case of high pressure.

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Fig. 13: Preliminary design of spent nuclear fuel container dimensions.

Virtual Events

ATENA in the Cloud

As many of you might be working from home now, we think you may appreciate our offer to provide you with ATENA in the cloud. You can make use of our software with full capabilities and without any performance limitations. ATENA cloud is open to anyone, who wants to test ATENA or run a nonlinear analysis on a cloud.

If you are interested to learn more about this service or you seek to activate your cloud account, please kindly click here.

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Fig. 14: Example of ATENA analysis in the cloud showing the running nonlinear analysis and quick access dialog to manuals and example problems.

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Fig. 15: Pushover analysis of a high-rise building 3D model in ATENA.

ATENA Webinars 2020

 

ATENA 5.7 Demonstration No. 1

The focus of this first seminar is the new durability modules that allow you to model long term deterioration effects on reinforced concrete structures such as chloride ingress or carbonation and the resulting reinforcement corrosion. For those not yet familiar with ATENA we provide a brief overview of the model preparation, unique runtime visualization of results or concrete cracking visualization in the post-processor.

Watch record from the demonstration here.

ATENA 5.7 Demonstration No. 2

The seminar shows several methods for modelling reinforcement and pre-stressing in the new ATENA v5.7. Generally there are two types of reinforcement model in ATENA: smeared and discrete. In the smeared model, the reinforcement is considered in a smeared way basically as a composite material consisting of concrete and reinforcement. The second discrete model can treat each reinforcement individually. In the discrete model, the pre-stressing can be applied. The discrete model allows the consideration of bond between reinforcement and concrete. The bond model can be also used for the calculation of pre-stressing losses. The webinar goes over the reinforcement models available in ATENA, and how they can be used to simulate pre-stressing including the calculation of pre-stressing losses.

Watch record from the demonstration here.

ATENA 5.7 Demonstration No.3

The next webinar will be on Thursday, November 5th, 2020, 10-11am CEST is free of charge. For more information, please go here.

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Fig. 16: Crack development in the segmental pre-stressed bridge cantilever at collapse load from ATENA nonlinear analysis.

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Fig. 16: Announcement screen for GiD conference presentation.

GiD Convention 2020

 

Jan Cervenka, head executive officer of Cervenka Consulting s.r.o. presented "Advanced Modelling of Reinforced Concrete Structures Using ATENA Interface to GiD" in the GiDconventionOnline, July 20th. Video from this conference you can find on YouTube channel.

ATENA On-line Training

Due to the limited movement of people around the world, we are going to prepare next ATENA seminars as on-line trainings. We would like to invite you to participate to training on February 15-17, 2021 in Czech language and on June 14-16, 2021 in English language.
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:

- 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.
- ATENA-SARA: probabilistic modelling, reliability analysis.

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Fig. 17: Beautiful photo of Prague castle in autumn.

Where You Can Meet Us On-line

Cement Softwaredag
October 28, 2020

The Software Day is a study day where members, but also non-members of Cement (knowledge platform about concrete structures), can gain knowledge about the possibilities and developments in the field of software for constructors. Besides through various sub-sessions and presentations / demonstrations, you will get a good idea of the software that can help you with a good structural design.

ATENA 5.7 Demonstration No.3
November 5, 2020

Online webinar for everyone who wants to learn more about the new version ATENA 5.7.

The following topics will be covered:
- Overview of ATENA programs: ATENA Engineering 2D & 3D, ATENA Science: what is the difference between the products and when they should be used.
- Durability models: reinforcement corrosion due to chloride ingress and carbonation, modelling of concrete degradation due to alkali-silica reaction
- New model for fibre-reinforced concrete material based on added fracture energy
- Material driver for testing user or existing material models
- ATENA in the cloud: atenacloud.cervenka.cz
- Overview of ATENA beam, shell and solid elements and their connections

fib Shanghai
November 22-24, 2020

This event that originally supposed to be held in Shanghai, China and now is planned as an online symposium, jointly organized by the Chinese National Group of fib and Tongji University and focused on "Concrete Structures for Resilient Society”, covering the innovation from concrete materials to structures, and dedicates to bringing together all the engineers, scientists, specifiers, concrete technologists, researchers, academics, practitioners and professionals to share knowledge and learn about advances in the concrete and construction world.

Recent ATENA Articles

CERVENKA, J.: ATENA – GID Interface for Advanced Modelling of Reinforced Concrete Structures, GiD Convention 2020, https://www.gidhome.com/gid-convention/gid-convention-2020

CERVENKA, J., CORDES, T., BERGMEISTER, K.: Stabilitätsanalyse der Spritzbetonsicherung der Kaverne des BBT-Zugangstunnels, Baustatik – Baupraxis 14, © 2020, Universität Stuttgart, ISBN 978-3-00-064639-3, pp. 808-811 (acknowledgement GeoTech4)

CERVENKA, J., JENDELE, L., ZALSKY, J., PUKL, R., NOVAK, D.: Digital Twin Approach for Durability and Reliability Assessment of Bridges, fib Symposium 2020, www.fibshanghai2020.cn

IASIELLO, C., PEREZ CALDENTEY, A., CERVENKA, J., PRYL, D.: An Application of Confined Concrete Modeling to Three‐dimensional Nonlinear Finite Element Analysis: The example of tunnel boring machine lining joints. Structural Concrete. 2020; 116. https://doi.org/10.1002/suco.201900584

LI, W., TANG, S., HUANG, Z., YANG, X., SHI, T., XING, F. Shear Behavior of Concrete Beam Reinforced in Shear with Carbon Fiberreinforced Polymer Mesh Fabric (CFRP-MF) Configuration, Guangdong Provincial Key Laboratory of Durability for Marine Civil Engineering, Shenzhen University, Shenzhen 518060, China, May, 2020, https://doi.org/10.1016/j.engstruct.2020.110828

PUKL, R.: Advanced Computer Simulation of Concrete Structures. Keynote lecture at the 4th International Conference on Civil Engineering Research (ICCER) (online), INSTITUT TEKNOLOGI SEPULUH NOPEMBER, Surabaya, Indonesia, July 2020

PUKL, R.: ATENA and SARA – Software Tools Developed by Cervenka Consulting s.r.o. for Assessment of Civil Engineering Structures. Invited presentation at the 4th International Conference on Civil Engineering Research (ICCER) (online), INSTITUT TEKNOLOGI SEPULUH NOPEMBER, Surabaya, Indonesia, July 2020

Q. Y. WEI, W. XU, D. NOVAK, R. PUKL, D. Y. LI, M. S. CAO: Damage Detection in Sluice Hoist Beams Subject to Excitation at Resonance Frequency Band Based on Local Primary Frequency. VIBROENGINEERING PROCEDIA. OCTOBER 2019, VOLUME 2, ISSN PRINT 2345-0533, ISSN ONLINE 2538-8479, KAUNAS, LITHUANIA

RAFAEL, A., Sanabria DIAZ, SILVIA J. SARMIENTO NOVA, MARIA C.A. TEIXEIRA da SILVA, LEANDRO MOUTA TRAUTWEIN, LUIZ C. de Almeida: Reliability Analysis of Shear Strength of Reinforced Concrete Deep Beams using NLFEA. Engineering Structures 203 (2020) 109760

RIMKUS, A., CERVENKA, V., GRIBNIAK, V., CERVENKA, J.:, 2020, Uncertainty of the Smeared Crack Model Applied to RC beams. Engineering Fracture Mechanics, Paper ID: 107088. DOI: 10.1016/j.engfracmech.2020.107088. ISSN: 0013-7944

SUCHARDA, O.: Identification of Fracture Mechanic Properties of Concrete and Analysis of Shear Capacity of Reinforced Concrete Beams without Transverse Reinforcement, Department of Building Materials and Diagnostics of Structures, Faculty of Civil Engineering, VSB-Technical University of Ostrava, June, 2020, doi:10.3390/ma13122788

SUCHARDA, O., MATECKOVA, P., BILEK, V.: Non-linear Analysis of an RC Beam without Shear Reinforcement with a Sensivity Study of the Material Properties of Concrete, Dept. of Building Materials and Diagnostics of Structures, Faculty of Civil Engineering, VSB-Technical University of Ostrava, Czech Republic, Slovak Journal of Civil Engineering, Vol. 28, 2020, No. 1, 33 – 43

Recent Diploma and PHD Thesis with ATENA

ANGAR, M., M.: Reinforcement Layout in Concrete Pile Foundations. A study based on non-linear finite element analysis, 2020, ISBN: 978-91-7873-598-3, Stockholm, Sweden

CHEN, H.: Study of Shear Mechanisms and Strength of Concrete Deep Beams Based on Strut-and-tie Model, Hunan University, 9/2019, https://www.researchgate.net/publication/337592432

FANTON, A., R.: Numerical Analysis of Thermomechanical Behavior of Reinforced Concrete Slabs in Fire, 2019, https://www.researchgate.net/publication/338901452, Campinas, Brazil

PEREZ, J., A., PASHA, J.: Punching Shear in Concrete Flat Slabs Supported on Slender Edge Steel Columns, 2020, ISBN: 978-91-7873-597-6, Stockholm, Sweden

SERRAS, D., N.: Controlled Damage Based Design of Composite Structures under Seismic Loading, Ph.D. thesis 2019, Hellenic Open University,

 

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