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Ritakallio, Pekka; Björk, Timo Low-temperature ductility and structural behaviour of cold-formed hollow section structures - progress during the past two decades Steel Construction 2/2014 107-115 Articles

Kurzfassung

Cold-formed hollow sections are a widely used tubular construction material. The applicability, weldability and reliability of cold-formed rectangular hollow sections are sometimes questioned because of the consequences of cold forming and inhomogeneous cross-sections. One of the main concerns is related to the cold-formed corner areas and possible loss of toughness due to strain ageing in the vicinity of the welds. Conventional hot-rolled C-Mn steels are susceptible to strain ageing, and Eurocode 3 includes restrictions on welding in the cold-formed corner area. Both steelmaking and hot rolling have undergone crucial developments and this has had an impact on cold-formed hollow sections. Thermomechanically rolled fine-grain steels became state of the art at the end of the 1990s. This study confirms that cold-formed EN 10219 hollow sections made of suitable fine-grain steels have a similar Charpy-V toughness on the flat face and in the corner, and that even after ageing the transition temperature T40J in the corner area is at a very low level, typically below -50 °C. The load and deformation capacities of X- and K-joints fulfil the requirements without any noticeable ageing effects. The advances in steelmaking and hot rolling enable the manufacturing of reliable and versatile cold-formed EN 10219 hollow sections for welded structures with good low-temperature ductility even in the cold-formed corner area.

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Abspoel , Roland; Bijlaard, Frans Optimization of plate girders Steel Construction 2/2014 116-125 Articles

Kurzfassung

The costs of the self-weight of a structure have never been a real issue in the design of steel girders, since the material costs of a structural element are mainly determined by labour costs. The booming economies of China and India cause a continuously increasing demand for steel. This and the now stringent regulations regarding sustainability make material economy in design much more interesting.
In a material economy-driven plate girder design, the lever arm between the flanges will increase. This leads to a higher stiffness and bending moment resistance, but also to an increase in the web slenderness of the girder. This means that high-strength steels can be used, leading to a large reduction in steel consumption.
Eurocode 3, EN-1993-1-5, [1] restricts the web slenderness based on the formula to avoid flange-induced buckling, originally derived by Basler [2]. However, experimental and theoretical research conducted on 10 unstiffened plate girders with high web slenderness ratios at the Stevin II Laboratory of Delft University of Technology shows that this formula is too conservative.
This paper presents the results of this research and suggestions for a new plate girder design strategy.

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Raw Materials Improvement Report available Steel Construction 2/2014 125 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Lipp , Andreas; Ummenhofer, Thomas Influence of tensile chord stresses on the strength of circular hollow section joints Steel Construction 2/2014 126-132 Article

Kurzfassung

The current version of the Eurocode for the design of joints does not include any brace load capacity reduction for welded hollow section joints with tensile chord preloading as opposed to those without. However, the more recent 2nd edition of the CIDECT design guides or the ISO standard for welded hollow section joints includes a strength reduction due to tensile chord stresses. This paper presents the results of experimental and numerical investigations into how tensile chord stresses influence the capacity of circular hollow section X-joints. The conclusion of this study is a new chord load function proposal for circular hollow section joints subjected to tensile chord stresses.

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Kurrer, Karl-Eugen The History of Theoretical, Material and Computational Mechanics - Mathematics meets Mechanics and Engineering. From E. Stein (ed.) Steel Construction 2/2014 132 Book review

Kurzfassung

Keine Kurzfassung verfügbar.

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Gresnigt, A. M. (Nol); Karamanos, Spyros A. Response of steel tubes under concentrated lateral loads Steel Construction 2/2014 133-140 Article

Kurzfassung

Steel tubes may be loaded by concentrated lateral loads such as support or impact loads. Impact loading, for example, is an important load case for buried pipelines that are struck during excavation activities, or large-diameter tubes during transportation (handling accidents). This paper presents an analytical model based on shell theory to determine the elastic-plastic load deformation behaviour. Test results are given as well as the results of finite element calculations. The finite element results and the model equations are in good agreement with the experimental results and illustrate the tube denting response.

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March 2014 crude steel production Steel Construction 2/2014 140 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Helbig, Thorsten; Kamp, Florian; Oppe, Matthias Lazika Pier Sculpture - A crossover from sculpture to structure Steel Construction 2/2014 141-146 Reports

Kurzfassung

Lazika is a new city in Georgia located on the Black Sea coast. The one-hundred meter long Lazika Pier with its 31 m high landmark sculpture is one of the first structures to mark the beginning of the development of this new metropolis.
The sculpture designed by German architect Jürgen Mayer H. consists of stacked oval elements - so called blobs - organized in seven levels. The blobs are subdivided into vertical plain levels running in an orthogonal direction with a distance of 90 cm. Due to the exposed position, tough requirements concerning corrosion resistance and a pretty tight timetable for design, fabrication and erection, structural steel has been chosen as the building material. The sculpture consists of steel plates with varying thicknesses of 5 to 10 mm. Elements composed of plasma-cut plates were pre-fabricated within a site workshop and installed using mobile cranes. Exterior and interior lighting features provide a dynamic and pulsating look to the sculpture.

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Pfeiffer, Esther; Kern, Andreas Modern production of heavy plates for construction applications - controlling production processes and quality Steel Construction 2/2014 147-153 Reports

Kurzfassung

Modern steel and pressure vessel construction requires heavy plates with tailored properties. In addition to satisfying quality standards, delivery on schedule is an important requirement for building projects. To show how these demands on actual deployment of plates are realized, this paper discusses methods for optimum production planning and production control where the focus is upon improving the flow of work, thus gradually eliminating unevenness across the system to realize the demands. Owing to the complexity of the heavy plate production process, computer-based modelling of material flow processes is presented as a suitable tool. In addition, important aspects of quality assurance and quality control during the production of high-performance plates are summarized. The quality characteristics of the plates are suitable surface quality, flatness, dimensional accuracy und mechanical and technological properties. How these features are controlled during the production of heavy plates is presented systematically.

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Göppert, Knut; Haspel, Lorenz; Waldner, Dany Mobile pavilions for the fairground of the BASELWORLD - The world's leading watch and jewellery show BASELWORLD has been given a new look Steel Construction 2/2014 154-157 Reports

Kurzfassung

Most stands at last year’s BASELWORLD as well as the fairground have been fundamentally redesigned: Six crystalline pavilions that house food service, media relations and ticket office string through a mosaic of blooming flower beds. Together with the architectural practice dany waldner AG, schlaich bergermann und partner developed a modular system for mobile buildings that feature a quick and easy installation for versatile use while meeting high design requirements. Functional but elegant detailing was required starting with wide span customized multi-functional aluminium girders carrying the roof membranes, incorporating invisible stressing devices for the membrane, attachments of secondary girders, facade columns and facade panels as well as electrical power supply for the integrated illumination. Laminates of glass panes and varying metallised textiles were used to clad the facade panels made of light weight aluminium frames and connected with integrated connection devices. The structure is resting on legs adjustable in height and adaptable to varying inclination of the ground, requiring a series of movable parts to be designed for multi use, long term performance and corrosion resistance free of lubrication. Combining the advantages of stainless steel, bronze, aluminium and black steel in the strict content of requirements made the project a challenge somewhere between civil and mechanical engineering.

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People: Steel Construction 2/2014 Steel Construction 2/2014 157-159 People

Kurzfassung

Darko Beg (1954-2014)
Ram Puthli 70 years

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ECCS News: Steel Construction 2/2014 Steel Construction 2/2014 159-162 ECCS News

Kurzfassung

Events
Announcements
Technical Committees (TC) activities
Ongoing R 
Publications

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Theory of Structures - Fundamentals, Framed Structures, Plates and Shells. From P. Marti Steel Construction 2/2014 162-163 Book review

Kurzfassung

Keine Kurzfassung verfügbar.

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"A great time for young engineers" Steel Construction 2/2014 164-166 Interview

Kurzfassung

Keine Kurzfassung verfügbar.

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Announcement: Steel Construction 2/2014 Steel Construction 2/2014 166 Announcement

Kurzfassung

Keine Kurzfassung verfügbar.

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Contents: Structural Concrete 2/2014 Structural Concrete 2/2014 Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Bergmeister, Konrad The service life of any structure is due to the genius of the engineer who designs it - and should not be at the expense of the engineer maintaining it. Structural Concrete 2/2014 115-116 Editorial

Kurzfassung

Keine Kurzfassung verfügbar.

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Krokstrand, Ole H.; Ramstad, Reiulf; Hölmebakk, Carl-Viggo Splendid concrete architecture in National Tourist Routes in Norway Structural Concrete 2/2014 117-125 Technical Papers

Kurzfassung

The Norwegian Public Roads Administration started a programme named “National Tourist Routes in Norway” in 1994. Today it includes 18 selected routes from south to north. The uniqueness of these attractions lies in the spectacular architecture found at the viewpoints, places of interest and visitor centres located amid magnificent scenery.
The aim of the tourist routes was to strengthen Norway's position in the marketing of international tourism and to help promote local business.
The routes are carefully selected and allow tourists to enjoy some of the most spectacular scenery in the country. Young Norwegian sculptors and architects, and a few renowned ones from abroad too, were invited to take up the challenge of creating unique viewing platforms, service buildings, footbridges, ramps, benches and stairs to be placed along the different routes. All are so unique that tourists automatically stop as they drive along, not just to admire the scenery, but also the special objects.
Several of these objects are in concrete, and four are presented below. (Map references for the individual projects are listed for easy searching on Google Earth)

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Breitenbücher, Rolf; Meschke, Günther; Song, Fanbing; Zhan, Yijian Experimental, analytical and numerical analysis of the pullout behaviour of steel fibres considering different fibre types, inclinations and concrete strengths Structural Concrete 2/2014 126-135 Technical Papers

Kurzfassung

The pullout behaviour of single steel fibres embedded in a concrete matrix is investigated for various configurations of fibre types and embedment lengths and angles by means of laboratory tests and analytical models. Laboratory tests for fibre pullout are performed to investigate the fibre-matrix bond mechanisms. Parameters influencing the fibre pullout response, such as fibre shape, fibre tensile strength, concrete strength and fibre inclination angle are systematically studied. The effects of these parameters on the pullout force versus displacement relationship, fibre efficiency and fibre/matrix failure response are analysed based on the experimental results. For the analytical modelling of the fibre pullout behaviour of straight fibres, an interface law is proposed for the frictional behaviour between fibre and matrix. In the case of inclined fibres, the plastic deformation of the fibre and the local damage to the concrete are also considered. For hooked-end fibres, the anchorage effect due to the hook is analysed. Combining these sub-models allows the pullout response of single fibres embedded in a concrete matrix to be predicted. In addition, numerical simulations of pullout tests are performed to obtain insights into the local fibre-concrete interactions and to provide supporting information for the analytical modelling. The models are successfully validated with the experimental results.

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Groli, Giancarlo; Pérez Caldentey, Alejandro; Soto, Alejandro Giraldo Cracking performance of SCC reinforced with recycled fibres - an experimental study Structural Concrete 2/2014 136-153 Technical Papers

Kurzfassung

This paper presents an experimental campaign aiming to assess the cracking behaviour of flexural members made with self-compacting concrete (SCC) and reinforced with both rebars and steel fibres recycled from end-of-life tyres (ELT). The characteristics, constructability and performance of this new type of fibre are first discussed. The results of the tests carried out are then presented and discussed. The parameters that have been investigated are: &phgr;/&rgr;s,ef, concrete cover and fibre content. The results obtained show improvement in cracking behaviour, especially for low reinforcement ratios and large covers. Results are compared with the predictions of the recently published fib Model Code for Concrete Structures 2010. The main objective of this investigation is to evaluate the efficiency of a new type of fibre technology for crack width control of RC elements, with advantages in sustainability from the point of view of recycling and durability.

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Prince, M. John Robert; Singh, Bhupinder Investigation of bond behaviour between recycled aggregate concrete and deformed steel bars Structural Concrete 2/2014 154-168 Technical Papers

Kurzfassung

The results of 45 pullout tests on 8, 10 and 12 mm diameter deformed steel bars concentrically embedded in recycled aggregate concrete designed using equivalent mix proportions with coarse recycled concrete aggregate (RCA) replacement levels of 25, 50, 75 and 100 % are described here. Although consistent results were not obtained for the 8 mm bars, the normalized bond strengths of the 10 and 12 mm bars across all RCA replacement levels were higher for the RCA concretes compared with the natural coarse aggregate concrete, and they increased with RCA replacement levels. Brittleness index, an analogous parameter from rock mechanics, has been shown to be a relevant predictor of the measured bond strengths. An empirical bond stress-slip relationship has been proposed and it has been conservatively suggested that anchorage lengths for the 10 and 12 mm deformed bars in recycled aggregate concrete may be taken to be the same as those in natural aggregate concrete.

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Fan, Yuhui; Xiao, Jianzhuang; Tam, Vivian W. Y. Effect of old attached mortar on the creep of recycled aggregate concrete Structural Concrete 2/2014 169-178 Technical Papers

Kurzfassung

This paper first presents an experimental study on the shrinkage and creep behaviour of recycled aggregate concrete (RAC) with different recycled coarse aggregate (RCA) replacement percentages (i.e. 0 %, 33 %, 66 %, 100 %). The experimental results reveal that increasing the RCA replacement percentage can increase the shrinkage and creep of RAC. A numerical method for creep behaviour with old adhering mortar is also proposed by analysing the influence mechanism of creep and the volume content of old adhering mortar on the creep of RAC. It is found that the RAC creep is significantly influenced by old adhering mortar properties and its volume content. Finally, a numerical model of RAC creep is established by considering the influence of mechanical properties and the creep behaviour of old adhering mortar. It is proved that this model can calculate the creep of RAC.

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Liu, Xian; Yuan, Yong; Su, Quanke Sensitivity analysis of the early-age cracking risk in an immersed tunnel Structural Concrete 2/2014 179-190 Technical Papers

Kurzfassung

Engineers know only too well that early-age cracking accounts for the decrease of long-term serviceability for a majority of infrastructure. In immersed tunnels, early-age cracks may leave paths for aggressive media, which lead to deterioration and thus compromise durability. On the other hand, the cracking risk in concrete structures depends on a number of factors, such as material properties, construction methods, curing measures, etc., which make decisions complex.
This work presents the results of a sensitivity analysis of early-age behaviour for an immersed tunnel cast in situ. Numerical modelling and local sensitivity methods are employed to evaluate the sensitivity of early-age cracking to casting temperature, formwork conductivity, formwork removal time, curing temperature and ambient temperature. The numerical results indicate that the casting and curing temperatures appear to be the most dominant factors with regard to the whole fabrication period.
This study provides a realistic method for determining the uncertainty analysis of concrete structures at an early age, and identifies the most important factors during the fabrication of immersed tunnel segments, which is beneficial for further decisions related to the control of early-age cracking.

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Yuan, Yong; Chi, Yang Water permeability of concrete under uniaxial tension Structural Concrete 2/2014 191-201 Technical Papers

Kurzfassung

Concrete structures can suffer from water permeating under stresses. This paper investigates the surface water permeability of reinforced concrete elements subjected to uniaxial tension. A testing system was developed to combine a conventional loading machine with a surface permeameter. To eliminate the effect of initial absorption of water, calibration tests were conducted on plain concrete samples with different surface saturated states. The experiment presented is designed to test the surface water permeability of a structural member under uniaxial tension. Specimens were reinforced centrally with different sizes of steel bar and fabricated with normal-strength and high-strength concrete. A uniaxial tensile load was applied from 0.10 to 0.80 of estimated ultimate cracking load in 0.10 increments. At the same time, water permeability was measured at each load step. Test results give the relationship between water permeability of concrete member and tensile load levels.

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Yan, Dongming; Xu, Shilang; Chen, Genda; Li, Hedong Biaxial behaviour of plain concrete subjected to dynamic compression with constant lateral stress Structural Concrete 2/2014 202-209 Technical Papers

Kurzfassung

This study investigates the dynamic biaxial behaviour of concrete by testing more than 60 cubic specimens on a custom-designed, servo-hydraulic-controlled machine. Each specimen was axially loaded in compression at a constant strain rate of 10-5, 10-4, 10-3 or 10-2 s-1 while two opposite side faces were subjected to a constant confining pressure and the other two side faces were free. The confining pressure applied to each specimen was 0, 30.5, 61.0 or 91.5 % of its uniaxial compressive strength. Test results indicate that the biaxial strength of concrete increases with strain rate at a reduced slope as confining pressure increases. The failure mode of the concrete specimens was basically unaffected by the strain rate. An empirical relation for the ultimate strength of concrete in a biaxial stress state was developed taking into account the effects of both confinement and strain rate.

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