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Souza dos Santos, Eliane; de Miranda Batista, Eduardo; Camotim, Dinar Cold-formed steel columns under L-D-G interaction - Experimental investigation Steel Construction 3/2014 193-198 Articles

Kurzfassung

The paper addresses an experimental programme that is part of an ongoing investigation on the behaviour, strength and design of cold-formed steel lipped channel columns undergoing mode interaction involving local, distortional and global buckling. The 16 column specimens tested were selected to exhibit either (i) close local, distortional and critical buckling loads (PcrL ≍ PcrD ≍ PcrG) or (ii) PcrL ≍ PcrD (condition ensured via the cross-sectional dimensions) and PcrG up to around 20 % below or above that value (difference controlled via the column length). The test set-up, procedure and results are presented and discussed, and the failure load data obtained are used to explore the possibility of developing a design approach based on the direct strength method (DSM).

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Zhang, Xi; Rasmussen, Kim Tests of cold-formed steel portal frames with slender sections Steel Construction 3/2014 199-203 Articles

Kurzfassung

Cold-formed steel sections are widely used in many applications such as structural frames, scaffolding systems, purlins and storage racks. In particular, cold-formed steel portal frames can be an alternative to conventional hot-rolled steel portal frames for industrial, rural and residential low rise buildings. The advantages of using cold-formed steels include a higher strength-to-weight ratio and reduced material, erection and transportation costs.
Over the past two decades a number of researchers [1] to [3] have undertaken tests on cold-formed steel portal frames. The tests mainly focused on the behaviour of joints, and employed relatively stocky sections. Hence, they provided little insight into the effects of cross-sectional instability on the overall stability of the frame.
In this paper, three portal frame tests are described, the main purpose of which was to study the effect of cross-sectional instability on the two-dimensional sway failure of cold-formed steel. The tests demonstrated significant local and distortional buckling before reaching the ultimate load. Finite element models were calibrated against the tests. The calibrated models therefore can be used for a parametric study to investigate the significance of the additional second-order effects caused by local/distortional bucking. The paper details the tests and the numerical simulations.

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Steel frame for new extension to terminal at Oslo Airport Steel Construction 3/2014 203 News

Kurzfassung

Keine Kurzfassung verfügbar.

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Jordão, Sandra; Pinho, Marco; Martin, João Pedro; Santiago, Aldina; Neves, Luís Costa Behaviour of laminated glass beams reinforced with pre-stressed cables Steel Construction 3/2014 204-207 Article

Kurzfassung

Structural glass corresponds to an innovative material with extraordinary aesthetical and architectonic potential that has undergone significant technological advances in recent years, yielding it stronger and safer. For this reason, the use of structural glass has increased considerably in the last decade and is now an unavoidable presence in most of recent reference buildings.
The structural capacity of glass elements is brought in from reinforcing techniques of different types. One of the possibilities corresponds to pre stressed cables reinforcement. This technique is very effective in terms of resistance and deformability and corresponds to a light reinforcing element rendering the so called spider web effect. In the framework of the research project “S-Glass: Structural performance and design rules of glass beams externally reinforced” [1] study the behavior of laminated glass beams reinforced by too twin external steel rods.
The work presented in the current paper is within the framework of S-Glass project aiming at characterizing the behavior of reinforced laminated glass beams in the non-crack regimen. For this purpose experimental and numerical analysis were prepared. The numerical model was used for a cable layout optimization analysis. Furthermore an analytical solution is put forward, which tackles the beam-cable load transfer indetermination. Final conclusions are established on the bases of a comparison established between experimental, numerical and analytical results.

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Kido, Ewa Maria; Cywinski, Zbigniew The new steel-glass architecture of railway stations in Japan Steel Construction 3/2014 208-214 Report

Kurzfassung

The accelerating needs of communication have led to many modern railway stations made of steel and glass being built or upgraded all over the world during the last two decades. That trend, influenced by local architectural traditions, is clearly evident in Japan, too. This paper, focusing on that trend, is a continuation of the authors’ previous publication [1].

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News: Steel Construction 3/2014 Steel Construction 3/2014 215-217 News

Kurzfassung

De Rotterdam awarded best tall building in Europe
First structural components for Texas project have arrived
Double milestone: 150th anniversary of the Foundation Det Norske Veritas (DNV) and one year anniversary of its merger with Germanischer Lloyd (GL)
Well networked - Consense 2014 in Stuttgart with around 1,400 visitors
SUSCOS students at Politehnica University in Timis¸oara

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ECCS News: Steel Construction 3/2014 Steel Construction 3/2014 217-220 ECCS News

Kurzfassung

Events
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TC News
Publications

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Announcement: Steel Construction 3/2014 Steel Construction 3/2014 220 Announcement

Kurzfassung

Keine Kurzfassung verfügbar.

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Contents: Structural Concrete 3/2014 Structural Concrete 3/2014 Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Litzner, Hans-Ulrich Tempora mutantur...... Structural Concrete 3/2014 277-278 Editorials

Kurzfassung

Keine Kurzfassung verfügbar.

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Taerwe, Luc; Helland, Steinar Structural Concrete makes impact Structural Concrete 3/2014 279-280 Editorials

Kurzfassung

Keine Kurzfassung verfügbar.

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Kollegger, Johann; Foremniak, Sara; Suza, Dominik; Wimmer, David; Gmainer, Susanne Building bridges using the balanced lift method Structural Concrete 3/2014 281-291 Technical Papers

Kurzfassung

This article explains the process of developing a new method, called the balanced lift method, for constructing bridges based on an alternative to the bridge construction techniques used nowadays. The most common methods of building bridges are those using falsework or the cantilever method, but a rather uncommon method, the lowering of arches is seen as the origin of the balanced lift method. The idea was to create a method that would allow a bridge to be built in a very fast manner without the need for falsework, using prefabricated elements and assembling all parts together in a position - in this case vertically - that would simplify the construction process. In order to reach the final state of the bridge, the parts assembled vertically are rotated into their final horizontal position. This article contains descriptions of the development of the method, a large-scale test and two bridges already designed using the balanced lift method.

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Gama, David; Almeida, João F. Concrete integral abutment bridges with reinforced concrete piles Structural Concrete 3/2014 292-304 Technical Papers

Kurzfassung

The use of reinforced concrete (RC) piles in integral abutment bridges (IABs) has not been widespread due to concerns over pile flexibility and the potential for concrete cracking. This is the reason why the use of steel piles is the preferred solution in the United States. However, in various countries where IABs are still seldom used, RC piles are more readily available and economical. Hence, an understanding of the behaviour of IABs with RC piles can lead to a wider implementation of integral solutions. This paper presents the results of a parametric study conducted to evaluate how both the design variables and the accuracy of the modelling approach influence the potential use of integral solutions with RC piles in prestressed concrete bridges up to 200 m long. Finite element modelling was used and four levels of approximation (LoA) were established for the analyses, ranging from simple linear-elastic to more complex non-linear models. The results show that existing concerns over concrete cracking control can be overcome if adequate options in design are used together with the adequate LoAs in structural analysis. Integral solutions with RC piles for bridges up to 200 m long can generally be adopted, although in comparisons with non-integral designs a significant additional amount of prestressing steel is to be expected. The results also include a set of charts with practical estimates to help designers in their first approach to the preliminary design of an IAB.

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Nyhus, Bente Skovseth Consistent practical design of concrete structures Structural Concrete 3/2014 305-316 Technical Papers

Kurzfassung

The design of large concrete structures is a very complex area which requires specialized skills and specialized tools. Tools are available to design these structures efficiently. However, these design tools are based on inconsistency between what is assumed in the structural analysis and the sectional design. This inconsistency is believed to be conservative, but is such an approach always safe and cost-effective? In light of this, a design tool has been developed to eliminate this inconsistency. The program is called ShellDesign and the new method is called the “consistent stiffness method”. The method can be used in practical design and is a more efficient alternative to running non-linear analysis programs. In order to obtain a more rational and consistent design method for transverse shear, implementation of the modified compression field theory (MCFT) in ShellDesign is almost finished. The main advantages of developing ShellDesign are to increase the competitiveness of concrete structures, contribute to increased safety and also to increase operability and document robustness in existing structures.

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Belletti, Beatrice; Damoni, Cecilia; Hendriks, Max A. N.; de Boer, Ane Analytical and numerical evaluation of the design shear resistance of reinforced concrete slabs Structural Concrete 3/2014 317-330 Technical Papers

Kurzfassung

The aim of this research is to compare the predictions of the design load-carrying capacity of slabs obtained with simplified analytical and numerical procedures which can be readily used by analysts in the current design process. The research fits into a research programme initiated by the Dutch Ministry of Infrastructure and the Environment for the re-examination of the load-carrying capacity of existing bridges and viaducts, and the beams and slabs they include, through the use of non-linear finite-element analyses. The behaviour of reinforced concrete slabs subjected to concentrated loads close to their supports is investigated in this contribution. Three tests from a series of 18 slabs with a total of 108 tests, tested at Delft University of Technology, were selected as case studies and analysed with non-linear finite-element analyses and analytical models either proposed by design codes or available in the literature. The research agrees well with the philosophy of the fib Model Code for Concrete Structures 2010, which offers different analytical and numerical calculation methods for evaluating the design shear resistance of reinforced concrete members according to different levels of approximation. For the three slabs investigated in this study, it indeed pays to use higher levels of approximation. The highest level (level IV) based on non-linear finite element analysis gives the highest design load resistance, but still well below the resistance obtained experimentally.

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Siburg, Carsten; Hegger, Josef Experimental investigations on the punching behaviour of reinforced concrete footings with structural dimensions Structural Concrete 3/2014 331-339 Technical Papers

Kurzfassung

Punching tests on 13 specimens under uniform soil pressure were conducted to evaluate the punching shear behaviour of footings with practical dimensions. The test series included square footings with and without punching shear reinforcement. The dimensions of the footings varied between 1.20 × 1.20 m and 2.70 × 2.70 m and the slab thickness varied between 0.45 and 0.65 m, resulting in shear span-depth ratios a&lgr;/d between approx. 1.25 and 2.00.
In addition to the measured steel strains in the flexural reinforcement and the stirrups, the increase in the slab thickness as well as the saw-cuts were examined to investigate the internal cracking and failure characteristic. In combination with previous tests conducted at RWTH Aachen University, this test series permits a description of the effect of the main parameters on the punching shear strength of footings. These parameters are the size effect of the effective depth, the concrete compressive strength, the flexural reinforcement ratio and the punching shear reinforcement.

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Gupta, Pramod K.; Ahuja, Ashok K.; Khaudhair, Ziyad A. Modelling, verification and investigation of behaviour of circular CFST columns Structural Concrete 3/2014 340-349 Technical Papers

Kurzfassung

This paper is an attempt to provide a detailed procedure for the finite element modelling and simulation of concrete-filled steel tubular (CFST) columns subjected to axial compression using the commercial software package ANSYS 12. A modified material model for modelling the concrete core is described and explained. Composite action is modelled between the concrete core and the steel tube and the procedure is presented with the recommended properties for modelling such behaviour. The proposed model is then validated by comparing its numerical results with selected experimental results available in the literature. The proposed model is used to investigate numerically the load transfer mechanism of CFST columns filled with different grades of concrete in order to study the effect of this parameter - i.e. compressive strength of concrete core - on the load transfer mechanism in such columns. Further, the proposed model has been employed for investigating the confining pressure provided by the steel tube on the concrete core along the length of the CFST column.

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Won, Deok Hee; Park, Woo Sun; Yi, Jin-Hak; Han, Sang-Hun; Han, Taek Hee Effect of welding heat on precast steel composite hollow columns Structural Concrete 3/2014 350-360 Technical Papers

Kurzfassung

Steel composite hollow columns have been studied in order to ease their construction. Welding or bolting are mostly used for connecting the steel tubes of precast steel composite hollow columns. However, welding generally results in temperatures of about 20000 °C in the welding zone and 1300 °C around the welding zone. Thus, the strength of the concrete in regions close to a welding zone is reduced. In this paper, the effects of arc welding and electro-slag welding - two widely used methods for connecting the column modules of steel composite hollow columns - on the temperature change in the welding zone are studied by performing heat transfer analysis. The changes in the strength of the concrete are investigated for each welding method. The rate of decrease in concrete strength due to electro-slag welding was greater than that due to arc welding. In addition, an effective method using ceramic fibres is suggested for preventing strength reduction in concrete due to welding heat.

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Carpinteri, Alberto; Cadamuro, Erica; Corrado, Mauro Minimum flexural reinforcement in rectangular and T-section concrete beams Structural Concrete 3/2014 361-372 Technical Papers

Kurzfassung

The prescriptions provided by codes of practice for assessing the minimum reinforcement amount for strength purposes in reinforced concrete beams usually disregard the non-linear contribution of concrete in tension and size-scale effects. In the present paper, these phenomena are taken into account correctly in the description of the flexural failure in lightly reinforced concrete beams by means of a numerical algorithm based on non-linear fracture mechanics. In this context, the application of dimensional analysis permits a reduction in the number of governing parameters. In particular, it is demonstrated analytically that only two dimensionless parameters, referred to as reinforcement brittleness number and stress brittleness number, are responsible for the brittle-to-ductile transition in the mechanical response. According to this approach, new formulae suitable for evaluating the minimum reinforcement in practical applications is proposed for both rectangular and T-sections. A comparison with experimental results demonstrates the effectiveness of the proposed model for different reinforcement percentages and beam depths.

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Castel, Arnaud; Gilbert, Raymond Ian Influence of time-dependent effects on the crack spacing in reinforced concrete beams Structural Concrete 3/2014 373-379 Technical Papers

Kurzfassung

This paper aims to put into perspective the influence of long-term effects, such as concrete creep and shrinkage, on concrete cracking. Long-term experimental results obtained at the Centre for Infrastructure Engineering & Safety (CIES) are reported and compared to design estimates made using the fib Model Code for Concrete Structures 2010. The influence of factors such as stirrup spacing and concrete cover are discussed. Results show that time-dependent shrinkage-induced cracking can considerably modify the cracking patterns obtained in short-term tests. For crack control in real structures and for the development of models for inclusion in codes of practice, it is strongly recommended that account be taken of time-dependent effects. Limiting observations to those made in short-term tests may lead to erroneous conclusions that are simply not applicable for structures that are more than a few weeks old.

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Strauss, Alfred; Zimmermann, Thomas; Lehký, David; Novák, Drahomír; Ker ner, Zbyn k Stochastic fracture-mechanical parameters for the performance-based design of concrete structures Structural Concrete 3/2014 380-394 Technical Papers

Kurzfassung

The experimental results for quasi-brittle materials such as concrete and fibre-reinforced concrete exhibit high variability due to the heterogeneity of their aggregates, additives and general composition. An accurate assessment of the fracture-mechanical parameters of such materials (e.g. compressive strength fc and specific fracture energy Gf) turns out to be much more difficult and problematic than for other engineering materials. The practical design of quasi-brittle material-based structures requires virtual statistical approaches, simulations and probabilistic assessment procedures in order to be able to characterize the variability of these materials. A key parameter of non-linear fracture mechanics modelling is the specific fracture energy Gf and its variability, which has been a research subject for numerous authors although we will mention only [1, 2] at this point. The aim of this contribution is the characterization of stochastic fracture-mechanical properties of four specific, frequently used classes of concrete on the basis of a comprehensive experimental testing programme.

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Van Coile, Ruben; Caspeele, Robby; Taerwe, Luc Towards a reliability-based post-fire assessment method for concrete slabs incorporating information from inspection Structural Concrete 3/2014 395-407 Technical Papers

Kurzfassung

After a concrete structure has been exposed to fire, a combination of destructive and non-destructive testing, expert judgment and calculations is used to decide whether the structure should be demolished or repaired, or can continue to be used without repairs or rehabilitation. However, there are many uncertainties associated with both the fire duration and the effect of elevated temperatures on the residual mechanical properties of the materials. Consequently, the maximum service load after fire exposure should be assessed based on reliability considerations in order to provide an adequate level of safety. As this type of calculation is too complex and time-consuming for practical use, a reliability-based assessment tool has been developed for concrete structures and applied to slabs to determine the maximum service load after fire. When using the proposed method, a safety level is targeted which is comparable with the safety level associated with the Eurocode format for the design of new structures. It is concluded that the proposed assessment method is both user-friendly and directly applicable in practice.

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Mancini, Giuseppe; Tondolo, Francesco Effect of bond degradation due to corrosion - a literature survey Structural Concrete 3/2014 408-418 Technical Papers

Kurzfassung

Bond can play an important role in the assessment of existing structures, particularly when corrosion of reinforcement is to be expected. The results of bond tests on corroded bars embedded in concrete are not yet fully conclusive for the definition of bond degradation due to the effect of corroded reinforcement. The structural effects of bond degradation can assume a different importance following the resisting mechanism that is activated within the structure. A critical review of the data available is presented here; some aspects such as embedment length, corrosion rate and type of test are analysed.

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Wilhelm, Sebastian; Curbach, Manfred Review of possible mineral materials and production techniques for a building material on the moon Structural Concrete 3/2014 419-428 Technical Papers

Kurzfassung

This article provides an overview of the findings and production processes for the mineral materials that have been developed and tested worldwide in the past with regard to the establishment of a lunar base. Firstly, the aim of and procedure for constructing a lunar base are briefly outlined. Following that, the lunar environment factors and their influence on a possible structure are described. The paper then presents the advantages and disadvantages of the materials examined, such as sulphur concrete, cast basalt, lunar concrete or polymer concrete, on the one hand, as well as production processes investigated previously, such as sintering, geothermite reaction and 3D printing, on the other. One promising method is the dry-mix/steam-injection (DMSI) method for producing a lunar concrete as a possible material which was developed by T. D. Lin and is based on cement made from lunar resources.

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fib-news: Structural Concrete 3/2014 Structural Concrete 3/2014 429-437 fib-news

Kurzfassung

AAYE: award opportunity for young engineers; First fib PhD Symposium held in North America; International conference in Moscow attracts renowned specialists; Innovation in Oslo; NZCS: New Zealand's member group; Structural Concrete impact factor on the rise; fib Bulletin 72; Montreal: the state-of-the-art in FRC; Short notes; EWH Gifford † 1921-2014; Congresses and symposia; Acknowledgement

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