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A consistent approach for global buckling of steel structuresStahlbau7/2023452Empfehlungen der Redaktion

Kurzfassung

Keine Kurzfassung verfügbar.

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Nonn, Jonas; Wilden, Vera; Feldmann, MarkusA consistent approach for global buckling of steel structuresSteel Construction2/202393-104Articles

Kurzfassung

The “General Method” according to chapter 6.3.4 of EN1993-1-1 or 8.3.4 of prEN1993-1-1 deals with the verification of stability problems of frame and beam structures with loadings in-plane. The “General method” according to Eurocode is intended for the general case of a combined moment and normal force. For the choice of the reduction factor &khgr;op, there are two options for applying the reduction curve, either the minimum of lateral torsional buckling (LTB) and flexural buckling (FB) or a weighted combination of both. With the use of analytical derivations, it can be shown that this approach leads to inconsistencies which can possibly lead to incorrect results. In this paper an alternative approach is presented which leads to unification and fully mechanical justification in verification. The approach allows e.g. the verification of stability of an entire frame system directly and without interaction factors (as in the equivalent member method). In addition, the issue of a consistent equivalent imperfection is addressed. With the use of this method, geometrical non-linear analyses of structures showing out-of-plane instability can be omitted; only an in-plane calculation and a determination of a linear buckling analysis is necessary. Finally, examples are presented in this paper that demonstrate the application of the approach shown.

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Schanack, Frank; Ramos, Óscar Ramón; Osman, Juan Pablo; Oyarzún, PabloA contribution to understanding the influence of concrete cracking on timber concrete composite bridge beamsBautechnik2/2015105-110Aufsätze

Kurzfassung

Despite of widely implemented advances in TCC bridge technology, there are still no satisfying design recommendations that consider the influence of concrete cracking on the distribution of forces and deformation. A research project at Universidad Austral de Chile studied several aspects of concrete cracking in TCC bridges with timber beams of greater depth than width using elastic dowel-type shear connectors. One of the results of concrete cracking is a reduction of the slip modulus of the connectors. This weakening was simulated in shear tests by a small gap between the timber and the concrete. A test calibrated FEM model was used for a parametric study of 120 different cases, most of which did not show concrete cracking. Where concrete cracking occurred, it caused an increase in the timber tensile stresses and beam deflection of up to 20 %. We conclude that concrete cracking occurs when the timber-concrete depth ratio is less than four times the cubic root of the effective flange width of the concrete slab.

Beitrag zur Berücksichtigung des Einflusses der Rissbildung im Beton in Holz-Beton-Verbundbrücken
Trotz des hohen Entwicklungsstands der Holzverbundbrückentechnologie, fehlen ausreichende Entwurfsgrundlagen für die Berücksichtigung des Einflusses der Rissbildung auf die Schnittkraft- und Verformungsverteilung. Im Rahmen eines Forschungsprojekts an der Universidad Austral de Chile werden verschieden Aspekte der Rissbildung in Holzverbundbrücken mit Holzbalken mit größerer Höhe als Breite und elastischen stiftförmigen Verbindungsmitteln untersucht. Dabei wurde festgestellt, dass sich die Rissbildung auf den Schubmodul del Verbindungsmittel auswirkt. Dieser Einfluss wurde in Scherversuchen durch einen kleinen Spalt zwischen Holz und Beton simuliert. Anhand eines mit Versuchen kalibrierten FEM-Modells wurden eine Parameterstudie mit 120 verschieden Fälle durchgeführt. In den meisten Fällen tritt keine Rissbildung auf. Wenn es zu Rissbildung kommt, vergrössern sich die Holzzugspannungen und die Durchbiegung um bis zu 20 %. Wir stellen fest, dass Rissbildung auftritt, wenn das Bauhöhenverhältniss von Holz und Beton kleiner als die vierfache Kubikwurzel der mitwirkenden Plattenbreite der Betonplatte ist.

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Thun, HÃ¥kan; Ohlsson, Ulf; Elfgren, LennartA deformation criterion for fatigue of concrete in tensionStructural Concrete3/2011187-197Articles

Kurzfassung

A deformation criterion is proposed for the fatigue failure of concrete in tension. According to the criterion, a fatigue failure is imminent when the total deformation approaches the deformation at maximum stress in a corresponding static test. This criterion was originally proposed for bond slip by Balázs in 1991. It is tested on two series of new and old concrete cylinders loaded in cyclic tension. How the criterion may be used to predict the number of load cycles to failure for existing structures under cyclic tensile loading is also shown.

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Colombo, Matteo; Martinelli, Paolo; di Prisco, MarcoA design approach for tunnels exposed to blast and fireStructural Concrete2/2015262-272Technical Papers

Kurzfassung

A design procedure based on a simplified FE model for underground tunnels subjected to internal explosion and possibly preceded by fire accidents is proposed in this article. The procedure can provide a valuable tool for designers who have to check the structural safety of a tunnel for the case of an internal blast event. The tunnel geometry considered is the same adopted for the metro line in Brescia, Italy. It has an internal diameter of about 8.15 m, is about 13.7 km long and is located about 23.1 m below the surface. Six segments and a smaller key segment (6+1) make up the tunnel. The ring has an average width of about 1.5 m. The FE model is first tested under static serviceability loads. Dynamic analyses are carried out in order to reproduce the blast scenario. The aim of this work is to generate pressure-impulse (p-i) diagrams for underground tunnels for the case of internal explosion and pre-explosion fire actions. An ultimate limit state criterion based on the eccentric ultimate flexural capacity and capable of including fire-blast interaction is introduced. An innovative layered precast tunnel segment solution made of different fibre-reinforced cementitious composites is compared with a traditional solution with the lining section made of reinforced concrete. The potential applications of this new solution are also discussed in the paper.

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Taido, Y.; Hayashi, H.; Kitada, T.; Nakai, H.A Design Method of Wide Stiffened Plates subjected to Uniaxial and Biaxial Compression (Entwurfsmethode für breite, ausgesteifte Platten, die durch einachsigen und zweiachsigen Druck beansprucht werden).Stahlbau5/1985149-155Fachthemen

Kurzfassung

Es wird über Berechnungsmethoden zur Ermittlung der Traglast ausgesteifter Deck- und Bodenbleche von flachen Kastenträgern infolge ein- und zweiachsiger Druckspannungen berichtet.

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Maraveas, Chrysanthos; Swailes, Thomas; Wang, YongA detailed methodology for the finite element analysis of asymmetric slim floor beams in fireSteel Construction3/2012191-198Articles

Kurzfassung

The aim of this paper is to present a detailed methodology for the three-dimensional finite element analysis of asymmetric slim floor beams under fire conditions. A fully controlled solution process is suggested through a detailed step-by-step presentation of the simulation parameters incorporated into the model. Work has been carried out so that any asymmetric slim floor beam can be assessed using the same consistent method, which is validated against two reported fire tests. Time-temperature and time-vertical displacement curves are calculated for the appropriate comparisons with experimental results, which show that the proposed methodology can accurately predict the thermal and structural behaviour of such beams.

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A Eurocode-compliant design approach for cold-formed steel sectionsStahlbau7/2023460Empfehlungen der Redaktion

Kurzfassung

Keine Kurzfassung verfügbar.

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Ungermann, Dieter; Lema ski, Tim; Brune, BettinaA Eurocode-compliant design approach for cold-formed steel sectionsSteel Construction2/202378-92Articles

Kurzfassung

A Eurocode-compliant design approach was developed for the design of thin-walled cold-formed steel sections which combines the AISI S100-16-Direct Strength Method (DSM) with the design provisions of EN 1993-1-3. The new design approach transfers the cross-sectional resistance determined acc. to DSM based on numerical elastic buckling analyses on the gross cross-section into the global member verification acc. to EN 1993-1-3. Additional factors were introduced to optimize the new approach, e.g., to account for the effects of the nonlinear stress distribution in cross-sections subject to local and/or distortional buckling. Within the framework of the German research project FOSTA P1328/IGF 19964, an extensive series of tests on differently shaped, perforated, and unperforated cold-formed sections in compression and bending were conducted which serve to analyze the buckling phenomena and the load-bearing capacity and to validate the new design approach. In addition, a numerical model was developed, calibrated to the tests, and used for further parametric analyses on the load-bearing capacity of cold-formed sections.

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Dumas, PhilippeA European perspective of the development of deep geothermal in urban areas - Smart thermal grids, geothermal integration into smart citiesGeomechanics and Tunnelling5/2016447-450Topics

Kurzfassung

The future of our energy supply systems is moving towards Smart Cities and Smart Rural Communities, where the integration of combined technologies using renewable energy sources reduces environmental impact and offers citizens a better quality of life. Geothermal has a particularly important role in smart electricity and thermal grids, since it can deliver both heating and cooling, and electricity.
Shallow geothermal, using heat pumps, is a key energy source for smart energy systems. It provides solutions for the future energy system by coupling smart thermal and electricity grids with underground thermal storage and by providing reliable and affordable heating and cooling supply to both urban and rural areas.
As these technologies can be installed in grid and off-grid heating and cooling systems, they perfectly fit the new smart cities and rural communities approach.
In addition, there is also an important role for shallow geothermal energy in connection with and management of smart electricity grids. Geothermal heat pumps can provide demand response services, thereby contributing to grid stabilisation, whilst Underground Thermal Energy Storage (UTES) is an excellent storage solution. Shallow geothermal technologies will be utilised in the next generation of district heating: Smart Thermal Grids.

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A house with sweeping lines / Ein Haus mit SchwungMauerwerk3/2017204-205Wettbewerbe

Kurzfassung

Keine Kurzfassung verfügbar.

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A Lego-like steel-framed system for standardization and serial productionStahlbau5/2023286Empfehlungen der Redaktion

Kurzfassung

Keine Kurzfassung verfügbar.

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Odenbreit, Christoph; Yang, Jie; Romero, Alfredo; Kozma, AndrásA Lego-like steel-framed system for standardization and serial productionSteel Construction1/202356-64Articles

Kurzfassung

A Lego-like steel-framed structural system has been developed within the frame of an RFCS project, REDUCE, to facilitate 1) deconstruction of composite structures, 2) circularity at structure and element levels, and 3) serial production in construction by promoting a greater standardization of structural elements. The system utilizes innovative demountable shear connections for composite flooring solutions with precast concrete elements, and adjustable steel connections for use in both beam-to-beam and beam-to-column connections. The first use case of the structural system has been realized in the Petite Maison project which is a demonstration project for circularity and contributes to the event ESCH2022. Each construction element is linked to a digital database and remains available for future reuse, as a result of the plug-and-play, demountable and robust features of the developed system. This paper presents the proposed demountable system, the results from experiments and finite element analyses on the behaviour of shear connections, composite beams, and steel connections, and indicates the analysing methods for structural engineers to open a pathway for full implementation of the structures built into digital tools, fabrication, and construction.

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Misiek, Thomas; Norlin, Bert; Höglund, TorstenA look at European buckling curves for aluminium membersSteel Construction2/2019141-155Articles

Kurzfassung

Numerical investigations of compression members made of aluminium are presented and recommendations for reorganizing the buckling classes and curves are derived from these. Finally, the curves are compared with test results.

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A membrane canopy for the roof of university buildings in TurinSteel Construction4/2013270News

Kurzfassung

Keine Kurzfassung verfügbar.

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Balint, G. S.A Method for the Analysis of Frames with and without Sidesway.Stahlbau7/1972218-223Fachthemen

Kurzfassung

Keine Kurzfassung verfügbar.

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Shonfield, Peter; Anderson, Jane; Boyd, SarahA methodology for assessing the environmental benefits of DRAGON technologyGeomechanics and Tunnelling4/2015333-339Topics

Kurzfassung

Most excavated material generated from tunnelling projects ends up being deposited on land. The EU funded project “DRAGON” aims to develop technologies to analyse and characterise this material so that the potentially usable fraction can be easily separated from non-usable material. Increasing use of this material by external industries will improve resource efficiency while reducing landfill quantities and disposal costs. One of the project goals is to assess the potential environmental benefits/costs of applying DRAGON technology to planned future EU tunnelling projects. A three stage approach has been adopted to meet this goal. Firstly, the potential for diverting material from landfill must be assessed. To account for the diversity of tunnelling projects, this will be based on an average of 54 recent tunnelling projects. Secondly, a life cycle assessment (LCA) model will be created to allow each of these tunnelling projects to be analysed and the potential benefits of using DRAGON technology will be compared against the ‘business as usual’ case. These results will then be averaged to give the expected environmental costs/benefits per t excavated material. Finally, these costs/benefits will be scaled up to account for the expected amount of material from future European tunnelling projects - expected to be around 800 m. t.

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Seidel, Marc; Coronel, Maria CarmenA new approach for assessing offshore piles subjected to cyclic axial loadinggeotechnik4/2011276-284Fachthemen

Kurzfassung

A new requirement of the BSH (Bundesamt für Seeschifffahrt und Hydrographie, the regulatory authority for offshore wind farms in Germany), is the assessment of the effect of cyclic loading on the capacity of foundations supporting offshore wind turbines. There are few practical design methods until now. This paper presents a new approach for assessing offshore piles subjected to cyclic axial loading, which combines two known methods, the approach for static loading as developed by the Imperial College of London (termed ICP approach) and a load-transfer-approach as incorporated in software “RATZ” for cyclic loading. Results using this method are compared against tests performed for the Health & Safety Executive (HSE) in Dunkirk and very good agreement is found.

Ein neuer Ansatz für die Bemessung axial-zyklisch belasteter Pfähle von Offshore-Konstruktionen.
Es ist eine Anforderung des BSH, dass die Wirkung zyklischer Belastung auf die Tragfähigkeit von Fundamenten von Offshore-Windenergieanlagen beurteilt wird. Bisher sind praktisch anwendbare Bemessungsmethoden selten. In diesem Beitrag wird ein neuer Ansatz vorgestellt, der zwei bekannte Methoden kombiniert, die ICP-Methode für die statische Belastung und ein Ansatz über Last-Verschiebungskurven für zyklische Belastung. Ergebnisse, die mit dieser Methode erzielt werden, werden mit Versuchen verglichen, die für die HSE in Dünkirchen durchgeführt wurden, und eine sehr gute Übereinstimmung wird festgestellt.

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Müller, Frank; Kohlmeyer, Christian; Schnell, JürgenA new approach for calculating the internal forces, moments and deflections of sandwich panels with reinforced concrete facingsStructural Concrete2/2016152-161Technical Papers

Kurzfassung

Software for calculating the internal forces, moments and deflections of sandwich elements with reinforced concrete facings has been developed as part of a research project at Technische Universität Kaiserslautern. Sandwich elements with stiff concrete facings are internally statically indeterminate. Cracking of the concrete facings leads to a redistribution of the internal forces and moments over the length and across the cross-section of the element. This redistribution must be considered in the structural design of such elements.
An existing program for calculating metal-faced sandwich elements was considerably extended by an iterative approach that allows the internal forces and moments to be calculated with the exact stiffness of the cracked facings. This iterative approach and the calculation algorithm behind the new software, called swe2+, are explained in this paper. A verification of the calculation results and a parametric study of a two-span sandwich element are also presented.

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Stroetmann, Richard; Kästner, ThoralfA new design model for welded joints - Experimental investigations of welds on high-strength steelsSteel Construction3/2021138-149Articles

Kurzfassung

In the AiF-FOSTA research project P1020 [1], a new design model for welded joints was developed. In this context, a small scale test on flat tensile specimens was designed, with the help of which various influences on the strength and ductility of the welds were investigated. Furthermore, extensive tests were carried out on overlap joints, cruciform joints with double fillet welds as well as partially and fully penetrated butt joints. This was done to calibrate the weld construction factor &agr;w, which takes into account the influence of the type of joint on the load-bearing capacity. In the following article, after a short summary of the current state of research, the design model, and the results from the parameter studies on flat tensile tests are described in more detail in [2-4]. Subsequently, the test program on welded joints and the calibration of the weld construction factor &agr;w are presented. Finally, the results of the design model and the tests carried out are compared with test results from other research projects and the design model of prEN 1993-1-8 [5].

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A new design model for welded joints: Experimental investigations of welds on high-strength steelsStahlbau10/2021748Empfehlungen der Redaktion

Kurzfassung

Keine Kurzfassung verfügbar.

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Llinares, Monica Aracil; Schöne, Lutz; Weininger, FlorianA new ETFE façade creates a landmark for Puebla F.C.Steel Construction2/2016151-155Articles

Kurzfassung

Cuauhtémoc Stadium, a first division football stadium in Puebla, México, with more than 51 000 seats, has recently been completely renovated. The brand-new façade has become an icon for the club and for the city. The façade is designed as a skin of single-layer ETFE foil in a combination of three different shades of blue and translucent white. The design and construction of the façade is the result of an international collaboration between local contractor DÜNN Lightweight Architecture, from Zapopan, Mexico, and LEICHT Structural engineering and specialists consulting GmbH, based in Munich, Germany. This paper will elaborate on the boundary conditions of the project and the technical decisions made for the construction of the façade.

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Beccarelli, Paolo; Maffei, Roberto; Galliot, Cédric; Luchsinger, Rolf H.A new generation of temporary pavilions based on Tensairity girdersSteel Construction4/2015259-264Articles

Kurzfassung

This paper provides a detailed overview of the design and construction of a series of temporary pavilions based on the Tensairity® principle. The pavilions are currently used in the Superbike racing category (Ducati Superbike Team), for the Audi tron Sailing Series, the ISAF Sailing World Cup and for other temporary events (3KIT pavilion). The paper describes the Tensairity® principle, the architectural and structural design of the pavilions, the manufacturing of the components and the assembly of the Tensairity® roofs.

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Gupta, Pramod K.; Khaudhair, Ziyad A.; Ahuja, Ashok K.A new method for proportioning recycled concreteStructural Concrete4/2016677-687Technical Papers

Kurzfassung

A new modified mix proportioning method for producing normal-strength concrete using recycled concrete aggregate, called the equivalent coarse aggregate mass (ECAM) method, is proposed in this paper. The basic concepts of the proposed method with calculations for mix design are presented by designing 14 mixes and testing 99 concrete samples (57 cubes and 42 cylinders). Experimental work was carried out in two phases. In the first phase, an experimental programme was conducted to verify the proposed mix design method by studying a single parameter - uniaxial compressive strength. Five different mixes with initial 0, 25, 50, 75 and 100 % replacement by mass were designed, cast and tested in this phase. It was concluded from the first phase that the proposed method can be adopted for designing the recycled concrete up to a nominal replacement ratio of 50 %. Accordingly, the second phase of experimental study was carried out to design three different grades of concrete strength using the proposed method to investigate the mechanical properties of the recycled concrete. Seven different mechanical properties - compressive strength, splitting tensile strength, modulus of elasticity, Schmidt hammer test, ultrasonic pulse velocity test, fresh density and hardened density - were investigated and are presented and discussed here.

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Metalssi, Othman Omikrine; Kchakech, Badreddine; Lavaud, Stéphane; Godart, BrunoA new model for the analysis of the structural/mechanical performance of concrete structures affected by DEF - Case study of an existing viaductStructural Concrete6/20161104-1113Technical Papers

Kurzfassung

Concrete construction is becoming increasingly complex and the importance of producing structures that are both cost effective and durable in the long term has never been higher. Therefore, an understanding of concrete durability is considered fundamental to determine the service life of new or existing structures. However, at present a significant number of existing concrete structures and bridges have already been deteriorated by a chemo-mechanical process known as Delayed Ettringite Formation (DEF). This phenomenon causes expansion of the affected concrete, generally leading to cracking and a decrease of its mechanical properties. The disease or deterioration mechanism therefore induces serious problems regarding serviceability, sustainable operation and structural integrity, which makes it necessary to apply predictive models able to re-assess the mechanical state of the affected structures. In this way, chemo-mechanical modelling must be performed considering the influence of humidity, stiffness reduction and stress in the development of expansion.
The elaborated 3D model was applied to an existing viaduct affected by DEF. The displacements and stresses were computed based on the experimental data obtained from the in-situ measurements. The computed results highlight the relationship between the saturation degree and the expansion. Finally, comparisons between different calculations with and without considering the anisotropy of expansion and stiffness reduction are presented and discussed.

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