Forschung und Entwicklung Recherche et développement · 2018. 9. 20. · Structural Concrete Laboratory of EPFL, with more than 250 punch - ing tests on full-size specimens since

Forschung und Entwicklung

Recherche et développement

Research and Development

148

Foreword

Research efforts in the field of structural concrete have been intensively performed since its implementationsas a building material more than one century ago. The aim of these researches has been to eventually pro-vide comprehensive, consistent and safe design methods and to allow a continuous development ofStructural Concrete. Despite the significant advances performed, many topics remain still under discussion.Also, the evolution in the material has opened a wide variety of new questions. There exists thus currentlythe need to continue with research initiatives in order to better understand the material and structuralresponse of concrete works and to simplify them into sound and transparent design models.

In the following pages, an overview of the researches performed in Switzerland in the field of StructuralConcrete during the last four years is presented. It shows the large diversity and richness of topics of interest.

In the name of all the researchers contributing in the following pages, I would also like to sincerely acknowl -edge the various sponsors for supporting these research efforts, from which society largely benefits.

Aurelio Muttoni

Head of fib’s Swiss National Member Group

Lausanne, August 2018

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Next generation ofUHPFRC for sustainableconstruction

Main investigators: E. Denarié, A. Hajiesmaeili, H. MohamedAbdul

The embodied energy in UHPFRCis dominated by two components:steel fibres and clinker. In thisproject, UHPFRC mixes are deve-loped by means of the massivereplacement of clinker with lime-stone filler and of steel fibreswith high-performance syntheticfibres. The novel mixes maintainor improve the tensile hardeningand softening response and othermechanical properties, the time-dependent response and com-pactness when compared to current steel fibre reinforcedUHPFRC materials. The environ-mental impact is significantlyreduced.

Fatigue behaviour ofUHPFRC – RC elements

Main investigators: E. Brühwiler,T. Makita, X. Shen, B. Sawicki

The fatigue behaviour of elementsmade of plain UHPFRC, R-UHPFRC(reinforced with rebars) and R-UHPFRC – RC under uniaxial and bi - axial stress states is investigated.The domain of very high numbersof fatigue cycles, i.e. more than10 million cycles, is explored inorder to simulate fatigue loadingconditions relevant for bridges.Rules are established for thedesign of fatigue strengtheningof bridge decks.

Punching shear strengthening of slabsusing UHPFRC

Main investigators: E. Brühwiler,M. Bastien-Masse, P. Schiltz

To strengthen reinforced concrete(RC) slabs with deficient shearresistance, it is proposed to add alayer of 25 to 50 mm of UHPFRCwith small diameter rebars (R-UHPFRC). The research reveals amonolithic composite element be -haviour where the new UHPFRClayer acts as an external tensilereinforcement leading to a signi-ficant increase in the combinedbending-shear and punching shearresistance of the strengthenedelement.

École Polytechnique Fédérale de Lausanne

Laboratory for Maintenance and Safety of existing Structures (MCS)

Research is related to UHPFRC (Ultra-High Performance Fibre Reinforced Cementitious Composite Materials)produced from cement and other reactive powders, additions, fine hard particles, water, admixtures and alarge number of short and slender steel fibres. The targeted addition of a thin layer of strain-hardeningUHPFRC to an existing member in reinforced concrete (RC) enhances the structural resistance and the dura-bility of existing RC structures. This concept has been implemented and applied in Switzerland since 2004to enhance reinforced concrete structures and to make them durable and performant for future use.

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Punching of Concrete Slabs

Main investigators: A. Muttoni,M. Fernández Ruiz, J. Simôes, J. Einpaul, F. Brantschen

An important experimental efforthas been performed by theStructural Concrete Laboratory ofEPFL, with more than 250 punch -ing tests on full-size specimenssince the year 2000. On that basis, a mechanical model,the Critical Shear Crack Theory,has been developed. This model has been adopted forpunching shear design by theSwiss Concrete Code SIA 262(2003 and 2013) and by the fib’sModel-Code 2010. It is also incor-porated in the draft for the nextgeneration of Eurocode 2 (prEN1992-1-1:2018).

Research (2014–2018) sponsored by:Swiss National Science Foun dation,project # 200021_137658/1

Additional information: https://ibeton.epfl.ch/Recherche/punching/Default_e.asp

Seismic response of flatslabs

Main investigators: A. Muttoni, K. Beyer, I. Drakatos

The response of slab-column con-nections, particularly for memberswithout transverse reinforcement,is typically associated with limiteddeformation capacities.This issue has raised questionsabout the suitability and potentialrisks of the use of flat slabs relyingon frame action as the primarybracing system of a structure (orwhen soft bracing systems areprovided). This research, con -ducted by the Structural ConcreteLaboratory in conjunction withthe Earthquake Engineering andStructural Dynamics Laboratoryof EPFL, is based on specific testsand has led to the extension ofthe theoretical framework of theCritical Shear Crack Theory tocover these cases.

Research (2014–2018) sponsored by: – Cemsuisse, research project #

201201 – Swiss National Science Foundation,

project # 143747– Seismology and Earthquake

Engineering Research Alliance forEurope, Project #2017-2

Additional information: https://ibeton.epfl.ch/Recherche/sustainedloading/Default_e.asp

Fatigue response of concrete in shear

Main investigators: A. Muttoni,M. Fernández Ruiz, F. Natario

Many structural elements such asbridge deck slabs are subjected tocyclic actions such as those origi-nating from traffic loads. Thisissue might be decisive for thedesign and verification of theseelements. However, conventionaldesign methods have been ques -tioned as many phenomena in -fluencing potential redistributionsof internal forces (such as shearand flexural cracking) are usuallyneglected.The Structural Concrete Labora toryhas performed a detailed investi-gation of this topic combiningexperimental and analytical re -search, leading to practical designguidelines.

Research (2014–2018) sponsored by: Swiss Federal Roads Office, project # AGB 2009/008

Additional information: https://ibeton.epfl.ch/Recherche/shearslabsshells/Default_e.asp


Structural Concrete Laboratory

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Shear resistance of beamsand slabs without shearreinforcement

Main investigators: A. Muttoni,M. Fernández Ruiz, F. Cavagnis, R. Cantone

The topic of the shear resistanceof slabs without transverse rein-forcement such as the deck slabsof bridges or the top and bottomslabs of cut-and-cover tunnels isdecisive in many cases for thedimensions and economic effi-ciency of these members.Related to this topic, theStructural Concrete Laboratoryhas performed detailed testingprogrammes with innovative testsetups and measurement devices.The results have allowed for con-sistent progress in the understand -ing of the various contributionsof the potential shear-transferactions.

Research (2014–2018) sponsored by: -– Swiss Federal Roads Office,

project # AGB 2015/011 – Swiss Federal Roads Office,

project # AGB 2011/015

Additional information: https://ibeton.epfl.ch/Recherche/shearslabsshells/Default_e.asp

Shear Transfer in CrackedConcrete

Main investigators: M. FernándezRuiz, A. Muttoni, M. Tirassa

The consistent understanding ofthe capacity of cracked concreteto transfer shear forces requiresan accurate description of theengagement of aggregate inter-lock stresses for crack kinematicscorresponding to those observedin shear failures. To this end, the Structural ConcreteLaboratory is carrying out researchin collaboration with the Compu -ta tional Solid Mechanics Labora -tory of EPFL where refined expe-rimental measurements are per-formed. The results are used incombination with the concept ofthe scales of roughness to providea consistent framework for themodelling of the phenomenon.

Research (2014–2018) sponsored by: Swiss National Science Foundation,project # 200021_1169649

Additional information: https://ibeton.epfl.ch/Recherche/shear/Default_e.asp

Strength of concrete undersustained loads

Main investigators: A. Muttoni,M. Fernández Ruiz, D. Tasevski

Concrete may be locally subjectedto high level of stress in many si -tuations. As a consequence, micro-crack development and growthmay occur in a phenomenon called non-linear creep, potential-ly reducing the effective concretestrength, but also producingbeneficial stress redistributionsand therefore reducing the stressconcentrations.This phenomenon has been inves -tigated by the Structural ConcreteLaboratory by developing a con-stitutive model of concrete thatincludes the development ofmicrocracking in concrete. Thismodel has been validated byseveral specific experimental pro-grammes and has allowed for thedevelopment of simplified designapproaches.


Additional information: https://ibeton.epfl.ch/Recherche/sustainedloading/Default_e.asp

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Non-linear analysis ofslabs

Main investigators: A. Muttoni,M. Fernández Ruiz, R. Cantone,M-R. Backes

An accurate analysis of the re -sponse of concrete slabs is re -quired to suitably estimate theopening of the cracks and there-fore their ability to transfer shearstresses. This analysis is howeverrelatively complex as it needs toaccount for the stiffness andredistributions on the internalforces after flexural and shearcracking.A number of suitable strategiesfor such modelling is being deve-loped at the Structural ConcreteLaboratory, allowing for the per-formance of refined analysis andalso providing guidelines for sim-plified analyses.

Research (2014–2018) sponsored by: -Swiss Federal Roads Office, project # AGB 2015/011


Textile Reinforced Concrete

Main investigators: M. FernándezRuiz, A. Muttoni, P. Valeri

Textile Reinforced Concrete con-sists of a material where a non-metallic reinforcement (normallycarbon or glass fabric) is arrangedwithin a cementitious matrix. Thisreinforcement is insensitive tocorrosion and therefore allowsfor the use of cements with lowclinker content and the provisionof low concrete covers.Within this frame, the StructuralConcrete Laboratory is carryingout research to characterise themechanical performance andpotential applications of thismaterial for building sustainableand lightweight structures.

Research (2014–2018) sponsored by: – Cemsuisse, research projects

# 201407 and # 201801– Gerber Rüf foundation,

project # KP-290/18

Additional information: https://ibeton.epfl.ch/Recherche/textile/Default_e.asp

Stress fields for design andassessment of structuralconcrete

Main investigators: A. Muttoni,M. Fernández Ruiz, F. Niketic

The stress fields method, as thestrut-and-tie method, has beenvery successful in the design anddimensioning of new structures,as well as for checking existingstructures. They have inspirednumerous codes and internatio-nal recommendations.On this basis, the elastic-plasticstress field method has beendeveloped by the StructuralConcrete Laboratory. This topic hasbeen the subject of a number ofresearch studies, which involvedverifying it systematically in testsand checking the applicability ofthe method for complex details.


Additional information: https://ibeton.epfl.ch/Recherche/stressfields/Default_e.asp



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Shear strength of girdersand beams with transversereinforcement

Main investigators: A. Muttoni,M. Fernández Ruiz, M. Rupf, M-R. Backes

Design of girders and can be con-sistently performed by using equi-librium-based models. Yet, anumber of specific issues such asthe amount of shear transferredby the compression chord, thetransverse bending of the webs orthe activation of the prestressingtendons require accurate ap -proaches to suitably assess thevarious potential load-carryingactions.A series of research studies hasbeen carried out on this topic bythe Structural Concrete Labora -tory, by applying and extendingthe elastic-plastic stress fieldmethod. As a result, a number ofdesign recommendations andguidelines for practice have beenproduced.

Research (2014–2018) sponsored by: -– Swiss Federal Roads Office,

project # AGB 2006/015– Swiss Federal Roads Office,

project # AGB 2009/009


Bond, anchorage and reinforcement detailing

Main investigators: A. Muttoni,M. Fernández Ruiz, F. Moccia

The Swiss practice with respect toanchorage and detailing has beentraditionally very much inspiredby a rigid-plastic bond response.This approach has shown consis -tent results in many cases, butdoes not account for a number ofspecific issues such as size effect,the influence of poor bond condi-tions or the influence of crackingparallel to the bar axis.Following these observations, theStructural Concrete Laboratory isleading an effort to develop morecomprehensive models to consis -tently account for the phenome-non of bond and its influence ondetailing. The final aim will be toupdate current code provisions,thereby extending their validityand applicability.



Reliability analysis

Main investigators: A. Muttoni,M. Fernández Ruiz, F. Niketic, P. Valeri, Q. Yu

The topic of reliability analysisand safety format is becomingone of capital importance fordesign for a number of reasons,such as the possibility of usingnon-linear analysis methods aswell as the need to use new mate-rials (for instance textile concrete)with different responses in termsof deformation capacity and po -tential redistribution of forces.Within this framework, theStructural Concrete Laboratory isinvestigating the suitability andconsistency of classical safety for-mats and how they can be tai -lored or extended to other cases.

Research (2014–2018) sponsored by: – Swiss Federal Roads Office,

project # AGB 2009/009 – Cemsuisse,

research project # 201801

Additional information: https://ibeton.epfl.ch/Recherche/codes/Default_e.aspp



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Computer-Aided Design ofDiscontinuity Regions

Main investigators: J. Mata-Falcón, D. T. Tran, T. Galkovski,W. Kaufmann

Strut-and-tie models and stressfields are powerful design tools,but often tedious and of limiteduse for serviceability and defor-mation capacity checks. Disconti -nuity Region Design, a computer-aided stress field tool, overcomesthese limitations. Simi lar to theEPSF method developed at EPFL,it only requires basic material pro-perties known at design stage andcomputes compression softeningautomatically. Further, it accountsfor tension stiffening (using theTension Chord Model) and strainlimitations of concrete and rein-forcement to cover all ULS andSLS checks, including crack widthsand deformation capacity.

Research (2016–2018) sponsored by:Eurostars-2 (Horizon 2020 EU re -search and innovation programme),#10571In collaboration with IDEA StatiCa.

Additional information: http://www.kaufmann.ibk.ethz.ch/en/research/DR.html

Large Universal ShellElement Tester

Main investigators: W. Kaufmann,A. Beck, D. Karagiannis, D. Werne

The Large Universal Shell ElementTester is a worldwide uniquetesting facility. Combining theconcepts of the University ofToronto’s panel and shell elementtesters, it enables large-scale testson reinforced concrete elementswith dimensions of 2.0 ∙ 2.0 m anda variable thickness. Precise, gene -ral load combinations (8 stress re -sultants) can be introduced at theedges of the specimen by meansof 100 actuators (–1.6/+1.2 MNeach), controlled by 20 controlchannels. The setup can also beused for the testing of e.g. fibrereinforced concrete or subassem-blies of larger structures undermultiaxial loading.

Research (2015–2018) sponsored by:– ETH Zurich– industry

Additional information: http://www.kaufmann.ibk.ethz.ch/en/research/LUSET.html

Concrete hinges/partiallyloaded areas

Main investigators: T. Markić, W. Kaufmann

Despite having been studied andused for more than a century,there is still a remarkable knowl -edge gap regarding the behaviourof concrete hinges and partiallyloaded areas in reinforced con -crete. The project aims at deve lop -ing consistent mechanical modelsfor these structural elements, andtheir subsequent validation bymeans of large-scale experiments.Based on the outcomes, a new setof design rules and recommenda-tions will be proposed. In a firststep, stress fields for partially loaded blocks, accounting for thebeneficial effect of confinement(active, passive and geometrical)have been developed.

Research (2016–2018) sponsored by:cemsuisse (project number 201501)

Additional information: http://www.kaufmann.ibk.ethz.ch/en/research/betongelenke.html

Eidgenössische Technische Hochschule (ETH) Zürich

Chair of Concrete Structures and Bridge Design

DRD stress field for deep beam withopening.

Failed specimen of Pilot Test 1 in theLUSET at ETHZ.

Bottle-shaped stress field for partiallyloaded reinforced concrete blocks.

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Eidgenössische Technische Hochschule (ETH) Zürich

Chair of Concrete Structures and Bridge Design

Structural behaviour of retaining walls affected bylocal corrosion

Main investigators: S. Haefliger,W. Kaufmann, U. Angst

Many existing cantilever retain ingwalls are affected by severe localpitting corrosion of the main rein-forcement in the constructionjoint above the footing. This leadsto a strong reduction of both de -formation capacity and ultimateload. Furthermore, the missingductility inhibits a pronounceddecrease of earth pressure bydeformation of the wall (as typi-cally assumed in design), leadingto higher loads. Hence, seriousconcerns about the safety ofthese structures arise. The projectaddresses this issue, accounting forthe effects of local corrosion anddeformation-dependent loadingin collaboration with the Chairsof Durability of Engineering Ma -terials and Geomechanics at ETHZ.

Research (2016–2018) sponsored by:– Federal Roads Office (FEDRO) – Federal Office of Transport (FOT)

Additional information: http://www.kaufmann.ibk.ethz.ch/en/research/verformungsverhalten_win-kelstuetzmauern.html

Effect of transverse bend -ing on the shear capacityof concrete bridges

Main investigators: D. Karagiannis, W. Kaufmann

Increasing traffic loads and deckwidening projects often requirethe assessment of the webs of existing box girder bridgesagainst combined loading by lon-gitudinal shear and transversebending. Due to the presumedconservatism of current designmodels for this type of loading,strengthening is required in manycases. Through a combination oftheoretical investigations, large-scale experiments and numericalsimulations, this research projectaims at developing a mechani-cally consistent model that willenable a more realistic assess-ment of the load-bearing capacityunder combined in-plane shearand transverse bending, includingchecks of the deformation capacity.

Research (2015–2018) sponsored by:Federal Roads Office (FEDRO)

Additional information: http://www.kaufmann.ibk.ethz.ch/en/research/querbiegung_schub.html

Principle sketch of retaining wallaffected by local corrosion.

a) Segment of a box girder bridgeand b) isolated web element.

(a)

(b)

Strengthening a ribbedslab with UHPFRC

Main investigators: H. Martín-Sanz García, B. Herraiz, E. Chatzi,E. Brühwiler

The Du Pont building, erected in1913, is an existing and historicreinforced concrete structure inthe city of Zurich. As part of therenovation of the building, theslabs are to be strengthened byadding a 40 mm UHPFRC layer. Aseries of experiments took placeat the IBK Structures Lab (ETHZurich), using an embedded fiberoptic measurement system, toassess the actual capacity of theslabs, and investigate failuremechanisms. The project is a col-laboration between the Chair ofStructural Mechanics (ETH Zurich),the Structural Maintenance andSafety Laboratory (EPFL) and Dr.Lüchinger+Meyer BauingenieureAG.

Research (2015–2018) sponsored by: – Swiss National Science Foundation,

project # 407040_154060– PSP Properties AG

Additional information: http://www.chatzi.ibk.ethz.ch/people/research-staff/henar-martin-sanz.html

UHPFRC strengthened ribbed slab,extracted from the Du Pont buildingand prepared for testing at the IBKStructures Lab.

Chair of StructuralMechanics

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Empa, Swiss Federal Laboratories for Materials Science and Technology

Structural Engineering Research Laboratory

Temperature stability ofCFRP strips in bridges

Main investigators: J.M. Gallego,M. Breveglieri, C. Czaderski, J. Michels

In bridge construction, externallybonded carbon fibre rein forcedpolymer (CFRP) strips can be usedfor the flexural strength ening ofcantilevers in the transverse direc-tion of box girder bridges.Experiments were performed toexamine the temperature stabili-ty and durability of this type ofinstallation during mastic asphaltapplication. Tests on cantileversexposed to sun exposure overseveral years are still on going.Furthermore, thermo-mecha nicalmodels to estimate temperaturesin the adhesive, models for theresistance of the bonded systemand practical recommendationswill be developed.

Research sponsored by: Swiss FederalRoads Office (FEDRO), ResearchProject AGB 2012/001 (2013–2017)and AGB 2016/003 (2017–2019)

Additional information: https://www.empa.ch/de/web/s303/strenghening-concrete-structures

Near-surface mounted me -mory steel strengthening

Main investigators: B. Schranz, C. Czaderski, M. Shahverdi

A cost-effective, iron-based shapememory alloy (memory steel) wasdeveloped at Empa for applicationin civil engineering structures. Thememory steel can be produced inthe form of standard geometryribbed reinforcement bars. Theunique properties of the materialcan be utilized in a pre-stressedform of the near-surface mounted(NSM) strengthening techniqueusing grooves in the concretecover for building components inflexure. A PhD project at Empaaims at acquiring in-depth knowl -edge about the characteristics ofthe material, its bond in the grooves and its application bymeans of small to large-scaleexperiments as well as numericalinves tigations.

Research (2017–2021) sponsored by:Swiss National Science Foundation(SNF), Project No. 200021_175998/1

Additional information:https://www.empa.ch/web/s303/advanced-structural-materials

Prestressed shear strength -ening of RC beams

Main investigators: M. Shahverdi,C. Czaderski, J. Michels (Companyre-fer)

In this project, ribbed memorysteel bars produced by thecompa ny re-fer are used incombina tion with shotcrete forshear strengthening of reinforcedconcrete (RC) structures. The pre-stressing has the advantage thatthe shear cracks width can bereduced and new shear cracksoccur under higher loads. Theresults so far show the feasibilityof memory steel shear reinforce-ment. Large-scale experiments onT-beams with a length of 5.2 mare performed in order to studythe practical application andeffectiveness of memory steel forthe prestressed shear strengthen -ing of concrete beams.

Research (2016–2019) sponsored by:Innosuisse, CTI Project No. 18528.1PFIW-IW, Industry Partner: re-fer,Brunnen, Switzerland

Additional information:https://www.empa.ch/web/s303/advanced-structural-materials

CFRP strip strengthening on top of aRC box-girder bridge and its simulati-on on cantilever test beams subjectedto long-term sun exposure.

Above: principle of near-surfacemounted reinforcement (NSMR),Below: ribbed memory steel bars.

Schematic illustration of ribbed me mo -ry steel bars in shotcrete applicationfor shear strengthening of RC beamsand the shear cracks of the referencetest beam measured with DIC.

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Construction with wood-cement compounds andtimber

Main investigators: D. Zwicky, N. Macchi, A. Fridez, V. Sciboz,M. Maeder, M. Medziti

Pourable lightweight wood-basedconcretes (or wood-cement com-pounds, WCCs, respectively) weredeveloped and assessed withrespect to struc tural properties,targeting their structural combi-nation with timber.Composite slab and wall ele-ments were conceived and eva-luated experimentally and analy-tically in full-scale tests up to rup-ture and for long-term behaviour.Practical structural design ap -proaches were also derived.Further assessments targeted pro-perties of thermal and fire protec-tion, recyclability, eco-balance andeconomic competitiveness. Possi -ble use in residential, office andschool buildings was proven.

Research (2012–2017) sponsored by: – Swiss National Science Founda-tion,

project 4066-40_136918– Univ. of Applied Sciences and Arts

of Western Switzerland– ERNE Holzbau AG– Vial Charpentes SA

Additional information: – www.nfp66.ch > project Zwicky– researchgate.net/profile/Daia_Zwicky

Haute école d’ingénierie et d’architecture Fribourg HEIA-FR

institut des Technologies de l’Environnement Construit iTEC

Timber-WCC slab in full-scale test.

Thin UHPC layers to improve the seismic behaviour of structures

Main investigators: M. Devaux,D. Redaelli, M. Hayek, J. Moix

Ultra-High Performance Fibre-Rein forced Concrete (UHPFRC)allows for very thin (20–30 mm)but extremely resistant, robustand durable layers to be cast.With their strength and ductility,cast-in-place or precast UHPC lay-ers can be efficiently used as localreinforcement to improve theseismic behaviour of existing andnew structural elements made oftraditional materials (concrete,masonry and steel).Experimental and theoreticalresearch is ongoing to identifystructurally and constructivelyoptimized UHPC configurations,in order to provide engineers withpractical design guidelines.

Research (2015 to date) sponsored by: – Univ. of Applied Sciences and Arts

of Western Switzerland– Industrial partners

Additional information: itec.heia-fr.ch/FR/Projets

Cyclic test on masonry wall elementwith U-shaped corner strengtheningmade of thin UHPFRC layers.

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New development of aCRFP tensioning system

Main investigators: H. Stempfle,L. Abächerli, G. Borkowski

The tensioning system developedin the past by StressHead AG andLucerne University, was well re -ceiv ed nationally and to an extentinternationally in the area ofcomponent reinforcement. Theanchors used to date required attimes that existing reinforcementto be severed. For this reason, thetensioning system with anchorswas further developed for beamsand slabs so that force can beapplied without damaging theexisting reinforcement. In addi -tion, a design concept for thesystem was developed.

Research (2012–2015) sponsored by:– Innosuisse– Stresshead AG

Additional information: https://www.hslu.ch/de-ch/hochschule-luzern/forschung/projekte/detail/?pid=3927

Post-tensioning anchorwith highly resilient loadintroduction zone

Main investigators: H. Stempfle,M. Switalla, E. Schurtenberger

The challenges involved in pre-tensioning systems include forceintroduction and their mechani-cal constraints and engineeringdesign while at the same timemanaging to find an economicsolution. The objective of the pro-ject was to develop post-tension -ing anchors for flat slabs thatwould allow for the post-tension -ing of concretes with a lowerearly strength, for the benefit ofgood construction progress. Theload introduction zone was to beoptimised at the same time. Aspart of the work, a model forforce introduction in concretewas developed, taking compres -sive stress and tensile stress intoconsideration.

Research (2013–2016) sponsored by:– Innosuisse– VSL AG


Fatigue of bridge deckssubjected mainly to bending forces

Main investigators: K. Thoma, G. Borkowski, P. Roos

Within the framework of anFEDRO project (Swiss FederalRoads Office), a fatigue test onreinforced concrete componentswas planned, carried out and ana-lysed taking into considerationthe membrane state of stress(CMA) . In addition, the influenceof a CMA on the steel stressamplitudes using non linear finiteelements analysis of case studiesand samples was discussed. In aparameter study, the influence ofkey parameters (bond stiffness,flexural strength, etc.) on the CMAand the result ing steel stresseswere demonstrated.

Research (2011–2018) sponsored by:Swiss Federal Roads Office


Lucerne University of Applied Sciences and Arts

Competence Centre for Structural Engineering (CC KI)

Four-point bend test of the untensio-ned beam strengthened with CRFPtensioning system.

Pre-tensioned double-span slab:injection of tension cables.

Fatigue test of bridge deck.

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Lucerne University of Applied Sciences and Arts

Competence Centre for Structural Engineering (CC KI)

Efficient construction offrame corners in reinforcedconcrete

Main investigators: D. Heinzmann,K. Thoma, H. Stalder, A. Jäger

The research project aims at deve-loping a simple, efficient reinfor-cement layout for frame corners,which should enable a completetransfer of the load-bearing resis -tance of the adjacent compo-nents. The load-bearing behaviourof these frame corners is verifiedexperimentally with componenttests and an associated designconcept is developed based onthe Stringer table model.The result is an economical andpractical reinforcement layout forreinforced concrete construction.In further research projects,financed by Innosuisse, prefabri-cated discontinuity reinforcementelements are developed for moreproductive and efficient use inreinforced concrete construction.

Research (since 2017) sponsored by:cemsuisse

Punching of reinforcedconcrete slabs made fromrecycled concrete frommixed demolition waste

Main investigators: A. Kenel, M. Laurent, A. Jäger

The concrete building method isvery common in Switzerland (andin all industrialised countries). Toconserve gravel resources, concretecan be produced with recycled(mixed) demolition waste.In the leaflet SIA 2030:2010, thepunching of slabs made of recycledconcrete from RC-M mixed granu-late is treated very conservativelyor as lightweight concrete due tothe lack of test results. This project is intended to enablethe increased use of recycled con-crete from mixed RC-M demolitionwaste in building construction, inparticular for the slabs, and there-fore to conserve the resource (pri-mary) gravel.

Research (since 2017) sponsored by:– City of Zurich– F.J. Aschwanden AG– Kibag AG– Toggenburger AG


Fracture pattern of the test of aclosing frame corner.

Section of a tested punching slab.

Documents

Forschung und Entwicklung Recherche et développement · 2018. 9. 20. · Structural Concrete Laboratory of EPFL, with more than 250 punch - ing tests on full-size specimens since