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Randl, Norbert Design recommendations for interface shear transfer in fib Model Code 2010 Structural Concrete 3/2013 230-241 Technical Papers

Kurzfassung

Interface shear transfer between differently aged concretes is a topic that crops up frequently and in different situations in structural design. In the fib Model Code for Concrete Structures 2010 the fundamental basics of concrete-to-concrete load transfer are given in section 6.3 and the corresponding design rules in 7.3.3.6. The different potential mechanisms contributing to the shear resistance along the interface, i.e. adhesive bond, aggregate interlock, friction and dowel action, are thus combined and their relationship taken into account by interaction factors. This article summarizes the most important results from past and ongoing studies and presents the background to the theory forming the design basis of fib Model Code 2010, the “extended shear friction theory” (ESF).

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Belletti, Beatrice; Damoni, Cecilia; den Uijl, Joop A.; Hendriks, Max A. N.; Walraven, Joost C. Shear resistance evaluation of prestressed concrete bridge beams: fib Model Code 2010 guidelines for level IV approximations Structural Concrete 3/2013 242-249 Technical Papers

Kurzfassung

The design shear resistance of an existing structure can be evaluated with analytical design procedures and numerical procedures provided by non-linear finite element analyses. The new fib Model Code 2010 proposes different calculation methods that fall into four different levels of approximation. As the level of approximation rises, so the complexity and the accuracy of the calculated shear resistance increases. Non-linear finite element analyses belong to the highest level of approximation, but although they are more and more becoming a customary tool in the daily design process, building codes do not provide guidance on how to perform these analyses.
This paper describes non-linear finite element analyses performed on prestressed beams, which underwent shear failure during experimental loading, in order to assess and criticize the finite element approaches. The aim of this work is to propose guidelines for numerical simulations in order to reduce model and user factors. The results obtained from the non-linear finite element analyses have been compared with the analytical results using different levels of approximation. The design shear resistance obtained with the highest level of approximation, level IV, derived from non-linear finite element analyses, turned out to be higher than the design shear resistance obtained with analytical procedures (levels I/II/III).

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Ayoub, Essam; Malek, Charles; Helmy, Gamal Highlights of the design and construction of a 12 km elevated APM bridge project in Saudi Arabia Structural Concrete 3/2013 250-259 Technical Papers

Kurzfassung

The automated people mover (APM) bridge project constructed at Princess Nora University (PNU) in Saudi Arabia and inaugurated in May 2012 is a major project with many challenges in design and construction due to its strict time-frame compared with the big scale of the project. Therefore, the design had to be such that it ensured simplicity, time-savings, lowest costs, aesthetics and the high quality required for bridge project elements. For aesthetic reasons, a box section was chosen for all the APM bridge sections for the bridge project, including straight, bifurcation and curved parts. This paper highlights the efficiency of the precast concrete techniques used in the design and construction of big projects such as this elevated APM bridge project at PNU in Saudi Arabia.

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Zanuy, Carlos; Curbach, Manfred; Lindorf, Alexander Finite element study of bond strength between concrete and reinforcement under uneven confinement condition Structural Concrete 3/2013 260-270 Technical Papers

Kurzfassung

It is well known that many factors affect the bond behaviour between concrete and steel reinforcement. Most of them characterize the degree of confinement, which is necessary for an appropriate determination of the bond strength and bond-slip relationship according to most extended models. Nevertheless, there are situations where the confinement is not known in advance or it can hardly be defined. That is, for example, the case of reinforced concrete under transverse pressure or tension. Under such conditions the confinement varies both longitudinally and circumferentially. This paper presents a 3D finite element approach to study the bond capacity of cases where the bond strength of the specimen is the result of the different contribution provided along the steel-concrete interface and cannot be described uniquely. A surface-to-surface contact model with frictional behaviour and debonding is used to study the influence of the local stress state at the interface. The model is able to reproduce the different failure modes (splitting or pull-out) obtained in experiments and provide a rational explanation of the influence of transverse tension.

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Iskhakov, Iakov; Ribakov, Yuri Two-layer concrete bridge beams as composite elements Structural Concrete 3/2013 271-277 Technical Papers

Kurzfassung

Two-layer high-performance RC beams can be used in the traffic (longitudinal) direction of long-span bridges. The beam section consists of two parts: a bottom part made of normal-strength concrete (NSC), which has a U-type section, and an upper one made of steel fibre-reinforced high-strength concrete (HSC), which has a rectangular section. Using two-layer beams is logical because as the beam span becomes longer and the service load increases, so a higher concrete strength is required in the beam's compression zone to withstand rather large bending moments. As concrete in the tension zone of the section contributes little to the beam's loadbearing capacity, this zone is made of NSC. This is an important economical advantage of two-layer beams. Steel fibres are only used in the compression zone made of HSC. The addition of steel fibres results in a higher ductility for the HSC layer, allowing proper design of two-layer bridge beams for dynamic loads. The design parameters for such beams include the HSC class, where the HSC layer depth is known and is equal to the depth of the rectangular section (above the U-section). The bottom NSC part (U-section) of a long-span beam is usually prestressed. Taking into account this circumstance, the total beam section depth should be checked for the serviceability limit state.

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Yamanobe, Shinichi; Saito, Kimio; Ichinomiya, Toshimichi; Kanamitsu, Yoshihisa Bilateral loading experiment on and analysis of concrete piers using mortar-jointed ultra-high-strength fibre-reinforced concrete precast formwork Structural Concrete 3/2013 278-290 Technical Papers

Kurzfassung

The seismic performance of a reinforced concrete pier structure depends greatly on the plastic hinge region at the base of the pier. To improve the plastic hinge region of the structure, we propose using ultra-high-strength fibre-reinforced concrete (UFC) formwork for the concrete cover at the base of the pier. This study describes the structural characteristics of a pier with a base cast using mortar-jointed UFC formwork.
To investigate the structural characteristics, a bilateral circular cyclic loading experiment and a simulation analysis using a fibre model were conducted. The results show that the flexural strength remained stable under a large rotation angle. Even at the rotation angle at the ultimate limit state, crushing failure of the mortar did not occur and the ultimate limit state did not result from mortar damage, because the tensile strength of mortar-filled joints is close to zero, and thus excellent flexural crack distribution performance can be achieved.

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fib-news: Structural Concrete 3/2013 Structural Concrete 3/2013 291-297 fib-news

Kurzfassung

First International Conference on Concrete Sustainability (ICCS13) in Tokyo, Japan
fib Congress in Mumbai
fib Commission 6, “Prefabrication”: background and current activities
MC2010 meeting in Belgium
Sixth International Symposium on Strait Crossings
70th anniversary of fib Ukrainian national member NIISK
Avraham Pisanty 1936-2013
Short notes
Congresses and symposia

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Contents: UnternehmerBrief Bauwirtschaft 3/2013 UnternehmerBrief Bauwirtschaft 3/2013 Contents

Kurzfassung

No Abstract.

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Schalk, Günther Von neuen und verhinderten Gesetzen ? UnternehmerBrief Bauwirtschaft 3/2013 1 Editorial

Kurzfassung

No Abstract.

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Kurz infomiert UnternehmerBrief Bauwirtschaft 3/2013 2 Kurz informiert

Kurzfassung

Bau startet mit gemischten Gefühlen ins neue Jahr
Nächste Ausgabe der EnEV auf den Weg gebracht
Streit über Streitvermeidung - Adjudication in der Kritik

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Malkwitz, Alexander; Karl, Christian K. Chancen in der malaysischen Bauwirtschaft - auch für Mittelstand UnternehmerBrief Bauwirtschaft 3/2013 3-11 Berichte

Kurzfassung

Malaysia befindet sich aktuell in einem Stadium zwischen einem Schwellenland und einem technologisch leistungsfähigen Industrieland. Die aktuellen Entwicklungen erscheinen nicht nur für Großunternehmen attraktiv. Auch kleine und mittelständische Unternehmen könnten in verschiedenen Bereichen ihre Chancen nutzen.

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Übergangsregelung für Authentifizierung bis Ende August 2013 UnternehmerBrief Bauwirtschaft 3/2013 12 Berichte

Kurzfassung

No Abstract.

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Bruttorechnungen des Jahres 2012 über 150 Euro überprüfen UnternehmerBrief Bauwirtschaft 3/2013 12 Berichte

Kurzfassung

No Abstract.

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Schalk, Günther Klare Worte beim Tag der mittelständischen Bauindustrie UnternehmerBrief Bauwirtschaft 3/2013 13 Berichte

Kurzfassung

No Abstract.

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Haftet Prokurist für Steuerschulden der Firma? UnternehmerBrief Bauwirtschaft 3/2013 14 Berichte

Kurzfassung

No Abstract.

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Rabatte von Lieferanten an Arbeitnehmer kein Arbeitslohn UnternehmerBrief Bauwirtschaft 3/2013 14 Berichte

Kurzfassung

No Abstract.

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Englert, Florian Aktuelles aus der Rechtsprechung UnternehmerBrief Bauwirtschaft 3/2013 15-17 Berichte

Kurzfassung

No Abstract.

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Auszeichnung für Nationalstadion Warschau UnternehmerBrief Bauwirtschaft 3/2013 17 Berichte

Kurzfassung

No Abstract.

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Rüstige Frührentner dürfen 2013 mehr hinzuverdienen UnternehmerBrief Bauwirtschaft 3/2013 18 Berichte

Kurzfassung

No Abstract.

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Minijob 2013 - ein Fall für die Rentenversicherungspflicht? UnternehmerBrief Bauwirtschaft 3/2013 18-19 Berichte

Kurzfassung

No Abstract.

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UBB-Meldungen kurz und prägnant UnternehmerBrief Bauwirtschaft 3/2013 19 Berichte

Kurzfassung

No Abstract.

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Steuerung von Bauprozessen UnternehmerBrief Bauwirtschaft 3/2013 20 Buchtipp

Kurzfassung

No Abstract.

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UBB-Veranstaltungstipps UnternehmerBrief Bauwirtschaft 3/2013 20 Veranstaltungen

Kurzfassung

No Abstract.

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Inhalt: Bauphysik 2/2013 Bauphysik 2/2013 Inhalt

Kurzfassung

Keine Kurzfassung verfügbar.

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Fouad, Nabil A.; Sadek, Ehab F. Experimentelle und numerische Untersuchung zum Langzeitkriechverhalten von Wärmedämmplatten aus extrudiertem Polystyrol-Hartschaumstoff Bauphysik 2/2013 63-76 Fachthema

Kurzfassung

Extrudierter Polystyrol-Hartschaum (XPS) hat aufgrund seiner ausgezeichneten Eigenschaften als lastabtragende Wärmedämmung in letzter Zeit große Aufmerksamkeit erregt. Diese Art der Wärmedämmung wird häufig unter Plattengründungen eingesetzt, bei denen hohe Druck- und teilweise auch Schubspannungen auftreten. Damit die Dämmplatten sicher in diesem Bereich angewendet werden können, sollte ihr Kriechverhalten untersucht und bewertet werden, um mögliche unverträgliche Setzungen zu vermeiden. Das Hauptziel der vorliegenden Untersuchungen ist es, das Kriechverhalten von lastabtragenden XPS-Wärmedämmstoffplatten unter reinen Schubspannungs- und kombinierten Druck-Schubspannungszuständen zu prüfen und eine potentielle Auswirkung, welche die Druckbelastungen auf das Schub-Kriechdehnungsverhalten unter kombinierten Belastungszuständen haben könnte, zu untersuchen. Mit einem speziell dafür entwickelten Prüfstand wurden Versuche zum Kriechverhalten von XPS-Hartschaumplatten unter Schub- und kombinierten Druck-Schubspannungszuständen durchgeführt. Versuchsergebnisse zeigten einen leichten Anstieg des Kriechdehnungsverhaltens aufgrund der Einwirkung von Druckbelastungen in kombinierten Lastzuständen. Die Ergebnisse der Versuche zum Kriechverhalten wurden verwendet, um möglichst genaue Annäherungen zu erhalten, die das Kriechverhalten unter den genannten Belastungen darstellen. Eine Übersicht, wie das Kriechverhalten anhand der Finite-Elemente-Methode mithilfe von mikrostrukturbasierten FE-Modellen simuliert werden kann, wurde vorgestellt. Die Mikrostruktur wurde mithilfe von Röntgenstrahlung festgehalten und sichtbar gemacht. Die entwickelten mikrostrukturbasierten FE-Modelle wurden dann verwendet, um eine Parameterstudie zur Optimierung des Kriechverhaltens von XPS Hartschaumplatten unter Schub- und Druckbelastungen durchzuführen.

Experimental and finite element analysis of creep behavior of extruded polystyrene rigid foam.
Extruded polystyrene (XPS) rigid foams have recently attracted a great attention as a superior load-bearing thermal insulation material. This type of thermal insulation material is commonly used under raft foundations, where high levels of compression loads and sometimes shear loads take place. To apply these boards safely in such application areas, their creep behavior should be intensively evaluated and analyzed to avoid any hazardous potential settlement. The principle objective of the current research is to investigate the creep behavior of XPS load-bearing thermal insulation boards under pure shear and combined shear-compression stress states and to explore any potential effect the compression stresses could have on the shear creep strains under the combined loading state. Creep tests were performed on XPS rigid foam boards under shear and combined shear-compression stress states using a specially developed test set-up. Experimental results showed a slight increase in the creep shear strains due to the application of compression stresses in the combined loading conditions. Creep test results have been used to investigate the most accurate approach able to model and extrapolate the creep behavior under these types of stresses. An overview of simulating the creep behavior through finite element method using microstructure-based FE models was introduced. The microstructure was captured by the x-ray computer tomography imaging technique. The developed microstructure-based FE models were then used to carry out a parametric study aiming to optimize the creep response of XPS boards under shear and compression loads.

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