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Steel market outlook 2013/2014 Steel Construction 3/2013 185 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Thieme, Andreas; Schröter, Falko Modern heavy steel plates for use in offshore installations - characteristics and production processes Steel Construction 3/2013 186-190 Articles

Kurzfassung

Steels for structural applications for offshore oil and gas as well as offshore wind installations have to fulfil demanding requirements that exceed those for steels used in normal structural steelwork. The applicable steel grades must show an optimum trade-off between sufficient toughness and good strength properties, and at the same time allow easy fabrication, especially concerning weldability. Although sufficient toughness is of importance in order to avoid abrupt failure phenomena such as brittle fracture, good strength properties are necessary to minimize the dead weight of the structure and thus facilitate transport and erection process. The significance of good fabrication properties consist of two facets: good weldability results in easy processing procedures and thus cost-efficiency in fabrication; further, materials with good weldability exhibit a higher resistance to cracking phenomena in the heat affected zone and are therefore more “forgiving” when it comes to non-optimum welding conditions, which may occur during erection in harsh environments.
This steel has to be tailor-made at the steelworks, the aim being to produce it as cleanly as possible with specially adapted alloying concepts. To secure good properties in the half thickness portion of the plates, what is necessary for offshore plates, slabs and ingots have to show an accurate control of the mid thickness segregation. Additionally those plates need higher deformation ratios from slab to plate in order to get a dense structure also in the mid thickness by proper through thickness deformation. These materials are produced with various rolling and heat treatment processes, each chosen depending on the desired grade, thickness and weight of the final plate. The processes in use are normalization of the plates, thermomechanical controlled rolling and the quenching and tempering of the plates.
This article aims to support the designer or fabricator when selecting the steel grade by explaining the different production methods and the resulting properties with respect to the final use.

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Ummenhofer, Thomas; Weidner, Philipp Improvement factors for the design of welded joints subjected to high frequency mechanical impact treatment Steel Construction 3/2013 191-199 Articles

Kurzfassung

The effectiveness of high frequency mechanical impact treatment for increasing the fatigue strength of welded structures has been investigated in several research projects over recent years. Based on extensive fatigue test data, design recommendations have been developed by different institutions. Most recommendations provide fatigue strength improvement factors that consider beneficial effects due to the application of post weld treatment methods. Current design recommendations use fatigue test data derived from small-scale specimens, but only very few studies have focused on welded joints with a plate thickness > 15 mm. This paper reviews existing design recommendations and provides a database for welded joints with a plate thickness exceeding those already covered. Butt-welded joints, longitudinal attachments and transverse attachments are covered in particular. Based on the data evaluated, improvement factors are given for a stress ratio of R = 0.1 for axial loading.

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Baeßler, Matthias; Rücker, Werner; Cuéllar, Pablo; Georgi, Steven; Karabeliov, Krassimire Large-scale testing facility for cyclic axially loaded piles Steel Construction 3/2013 200-206 Articles

Kurzfassung

Offshore piles have to withstand predominantly cyclic axial loads when they are installed in multi-pile configurations, as in jacket foundations. The dimensions of the pile are governed by both the internal capacity and the fatigue behaviour of the steel cross-section as well as by its external capacity in the pile-soil interaction. Owing to the large numbers of piled foundations required for current and future offshore wind farms, there is an urgent need to optimize the dimensions and related costs of single piles. With regard to the pile capacity, two major topics of research are the determination of possible capacity gains due to pile ageing effects and proper consideration of cyclic degradation. In order to investigate both effects, a large-scale testing facility has been constructed at the BAM TTS site in Horstwalde near Berlin. This open-air facility allows large tubular driven piles to be loaded cyclically in both tension and compression while studying the ageing effects by introducing delays between the testing campaigns. First results already show a moderate increase in pile capacity over time. Concerning the anticipated capacity degradation of cyclically loaded piles, preliminary results show an unexpected behaviour. Additional tests are currently being conducted for further clarification.

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Founding of "Gesellschaft für Bautechnikgeschichte" Steel Construction 3/2013 206 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Schmidt, Michael; Fehling, Ekkehard; Braun, Torsten Grouted connections for offshore wind turbine structures, Part 1: Individual approval, materials and quality control Steel Construction 3/2013 207-215 Articles

Kurzfassung

On offshore wind turbine structures, grouted connections are widely used to connect the tower structure to the foundation while accommodating the unavoidable geometrical tolerances effectively. The long-term behaviour of high- and ultra-high-strength grouts primarily depends on the adequate strength and durability of the material plus the process reliability. The performance of the fresh and the hardened grout is influenced by many factors that have to be evaluated and considered individually with respect to the “rough” offshore conditions. Those factors are: mix performance and consistency, the ambient conditions at the place and time of use, the equipment for and stability of the mixing and casting processes, the length of casting time and the thermal and mechanical loads during the early stages. To ensure adequate long-term behaviour, a meaningful quality assurance system should be set up to cover both the materials and the processes. The article emphasises some fundamental experiences gained by the authors with numerous wind turbine parcs in the North Sea and the Baltic Sea.

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Fehling, Ekkehard; Leutbecher, Torsten; Schmidt, Michael; Ismail, Mohammed Grouted connections for offshore wind turbine structures, Part 2: Structural modelling and design of grouted connections Steel Construction 3/2013 216-228 Articles

Kurzfassung

In many cases, the design checks of grouted connections follow international standards which contain analytical design equations. In order to also obey mechanical consistency especially for structures with significant bending moment and to satisfy basic requirements according to the Eurocodes, different mechanical models have been used in practice in a number of cases. In this regard, non-linear finite element models as well as analysis with strut and tie models have been applied. Findings from these calculations as well as from experimental investigations on both the material and the structural level are analysed and compared. In conclusion, an improved design approach based on a strut model which is easy to handle is presented and exemplified.

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Kido, Ewa Maria; Cywinski, Zbigniew The new steel-glass architecture of buildings in Japan Steel Construction 3/2013 229-237 Reports

Kurzfassung

Practical examples of modern architecture in the western hemisphere based on structural compositions of steel and glass have been presented several times in recent years. In doing so, their theoretical background has also been discussed. This paper focuses on the relevant architectural manifestations in Japan. Buildings for commercial and public use are the sole interest here - with special emphasis on the ultramodern character of their design. It is planned to consider infrastructure elements such as railway stations and airport structures in a future article.

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Ernst , Claudia; Brunier , Knut The Design Carport - A self-supporting folded steel sheet structure Steel Construction 3/2013 238-241 Reports

Kurzfassung

In the design and making of complex architectural systems, sheet metal is still predominantly used as a cladding material. The objective here is to integrate innovative digital and analogue methodologies to develop a design system for a self-supporting lightweight structure entirely based on the use of sheet metal as a construction material.
A digital working methodology which is informed by fabrication techniques, material behavior and structural performance allows for a highly precise product and a coherent fabrication process.

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Eilzer, Wolfgang; Jun, Rolf; Angelmaier, Volkhard; Maier, Markus Hans-Peter Andrä reached 65 Steel Construction 3/2013 242-243 People

Kurzfassung

Keine Kurzfassung verfügbar.

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Hovering wings of light in Hamburg are completed Steel Construction 3/2013 243 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Announcement: Steel Construction 3/2013 Steel Construction 3/2013 243 Announcement

Kurzfassung

Keine Kurzfassung verfügbar.

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ECCS News: Steel Construction 3/2013 Steel Construction 3/2013 244-246 ECCS News

Kurzfassung

Events
Announcements
Technical Committees (TC) activities
TC News

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Contents: Structural Concrete 3/2013 Structural Concrete 3/2013 Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Foster, Stephen Physical understandings and development of mechanical models for the design of concrete structures Structural Concrete 3/2013 193-194 Editorial

Kurzfassung

Keine Kurzfassung verfügbar.

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Sigrist, Viktor; Bentz, Evan; Ruiz, Miguel Fernández; Foster, Stephen; Muttoni, Aurelio Background to the fib Model Code 2010 shear provisions - part I: beams and slabs Structural Concrete 3/2013 195-203 Technical Papers

Kurzfassung

This paper examines the evidence for the one-way shear model developed for the fib Model Code for Concrete Structures 2010 and provides examples of its application. For the design and analysis for shear, for members with and without shear reinforcement, the fib Model Code 2010 procedures have been developed from physical-mechanical models that are based on observed behaviour at the meso-scale level; they represent a significant advance over previous standardized empirical methods. In addition, an approach referred to as “level of approximation” (LoA) is incorporated where advanced models are simplified in a consistent and conservative way such that the designer can select the effort needed to justify their design. To illustrate the practical use of the models and the LoA approach, two examples are presented. The first is a deck slab of a cut-and-cover tunnel where design and possible refinements are discussed for a given configuration. The second is a prestressed concrete bridge girder, which is considered for the cases of design and for the analysis of an existing structure.

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Muttoni, Aurelio; Ruiz, Miguel Fernández; Bentz, Evan; Foster, Stephen; Sigrist, Viktor Background to fib Model Code 2010 shear provisions - part II: punching shear Structural Concrete 3/2013 204-214 Technical Papers

Kurzfassung

This paper outlines the theoretical background to the punching shear provisions implemented in the fib Model Code for Concrete Structures 2010 and presents a practical example of their application. The aim is to explain the mechanical model that forms the basis for the punching design equations, to justify the relevance of the provisions and to show their suitability for the design and assessment of structures.

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Fardis, Michael N. Performance- and displacement-based seismic design and assessment of concrete structures in fib Model Code 2010 Structural Concrete 3/2013 215-229 Technical Papers

Kurzfassung

The scope of fib Model Code for Concrete Structures 2010 includes the fully fledged performance- and displacement-based seismic design of new structures and assessment of existing ones. This part of fib Model Code 2010 covers buildings, bridges or similar concrete structures and aims to provide well-defined performance levels for specific seismic hazard levels. Detailing of members for ductility is not based on opaque prescriptions, as in current codes, but on transparent, explicit verification of inelastic deformation demands against capacity limits. The reference analysis method is non-linear dynamic, but under certain conditions inelastic deformation demands may be estimated from linear analysis and the 5%-damped elastic response spectrum; in that case force demands on force-controlled, brittle failure modes are estimated from the plastic mechanism through equilibrium. In order to predict the seismic deformation demands with some confidence, the analysis should use realistic values for the member secant stiffness up to the yield point. The paper explains the background to the expressions given for this property in fib Model Code 2010 as well as of those for the deformation limits used when verifying seismic deformation demands. The modifications to the shear resistance approach of fib Model Code 2010, which takes cyclic loading into account, are also explained and justified.

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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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