No short description available.

No short description available.

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.

No short description available.

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.

No short description available.

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.

No short description available.

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.

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.

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

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.

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.

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.

No short description available.

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.

The floods in the Czech Republic in the last few decades have resulted in a significant number of bridges having to be rebuilt. Unfortunately, the work meant long-term traffic closures for railway bridges, coupled with significant costs for renovation and for providing alternative transport services. As a result, the minimum clear headroom above the design flood level required for new bridges and for reconstructing existing bridges has been increased. This initiated a search for new approaches to designing individual parts of bridge crossings, aiming to comply with the stricter conditions. The research aims to decrease costs in comparison with the costs of raising the finished grade level of the railway, especially at places where adjacent sections such as railway stations etc. are connected.

In many practical situations, internal nodes connect beams with unequal depth whenever the span lengths are not uniform. Following the methodology defined in EC 3-1-8, this paper presents a component model that is able to reproduce accurately the complex behavior of welded beam-to-column joints with beams of unequal height, which corresponds to a node configuration that is not yet covered in the EC 3 design rules. Based on an experimental program carried out at the University of Coimbra, the relevant components for the column web panel under a non-uniform stress state are characterized, leading to the development of a new design procedure that extends the scope of EC 3-1-8.

Ein Komponenten-Modell für geschweißte Träger-Stützen-Verbindungen mit Trägern ungleicher Höhe.
In vielen praktischen Situationen verbinden bei unterschiedlichen Spannweiten innere Knoten Träger ungleicher Höhe. Entsprechend der in EC 3-1-8 festgelegten Methodik stellt dieser Aufsatz ein Komponentenmodell für eine genaue Nachbildung des komplexen Verhaltens geschweißter Träger-Stützen-Verbindungen mit Trägern ungleicher Höhe vor, was einer Knotenkonfiguration entspricht, die durch die EC 3-Bemessungsregeln noch nicht abgedeckt ist. Auf Grundlage umfangreicher Versuchsserien an der Universität von Coimbra werden die Komponenten für die Stützenstege unter ungleichmäßiger Belastung modelliert, was zur Formulierung eines neuen Bemessungsverfahrens führt, das den Umfang der im EC 3-1-8 dargestellten Möglichkeiten signifikant erweitert.

No short description available.

No short description available.

Die neue Eldetalbrücke ist ein wichtiger Teil des Lückenschlusses der deutschen Bundesautobahn A 14. Sie besteht aus zwei parallel verlaufenden Teiltragwerken in Stahlverbundbauweise. Die vier Hauptträger der Brücke sind als Stahlhohlkästen ausgebildet, die im Bereich der beiden größten Spannweiten voutenförmig nach unten erweitert sind. Insgesamt liegt die Brücke auf 14 Achsen auf, die aufgrund der schwierigen Baugrundverhältnisse auf Großbohrpfählen gelagert sind. Die zwei Lagerachsen mit den größten Vouten sind als Besonderheit als semi-integrale Verbundpfeiler ausgebildet, deren Planung und Bau eine Herausforderung für alle Beteiligten darstellten. Zusätzliche Einschränkungen bei der Zugänglichkeit erforderten kreative Lösungen bei der Stahlbaumontage. Mit einer Gesamtlänge von 506 m zählt die fertiggestellte Eldetalbrücke zu den größten Brückenbauwerken in Mecklenburg-Vorpommern.

The A 14 Eldetalbrücke - special features of the structural steelwork.
The new Eldetal Bridge forms an important part of the German Bundesautobahn A 14. The basic configuration of its dual carriageways is that of a reinforced concrete deck slab on top of in total four box girders with rectangular cross sections. In the largest spans, the box girders are haunched in elevation with a curved soffit. In total, the bridge is supported in 14 bearing axes; due to difficult soil conditions, the majority of them is founded on concrete piles. As a special feature, the two bearing axes next to the main span are designed as integral pillars; their construction was a challenge for the project partners. In addition, limited accessibility of some areas of the building site required several smart solutions during assembly. With an overall length of 506 m the Eldetal Bridge is one of the biggest bridges in the federal state of Mecklenburg-Vorpommern.

No short description available.

Die große Flexibilität für wechselnde wissenschaftliche Anforderungen wird durch ein weitspannendes, raumhohes und umlaufend auskragendes Stahlfachwerk ermöglicht. Der steife Dachkörper ruht auf regelmäßig angeordneten Stahlverbundstützen in der Nutzebene. Der Synergieeffekt aus der doppelten Funktion des Daches als Tragwerk und großzügiger Technikzentrale trägt zur Nachhaltigkeit des Gebäudes bei. Die flächig angeordneten technischen Anlagen erlauben die individuelle Anbindung der einzelnen Module, die Belegung kann sich den wandelnden Wissenschaftsanforderungen anpassen und vielfältige Nutzungsszenarien ermöglichen. Im Beitrag wird aus der Sicht der ausführenden Stahlbaufirma Christmann

:envihab Institute for aviation and space medicine Cologne - Zero gravity build with steel.
The great flexibility for changing scientific demands is made possible with a long spanning, story high and circumferentially cantilevering steel lattice. The stiff roof structure rests on regularly arranged composite columns in the actual building space below. The synergy effect of the double function as roof structure and spacious utility floor contributes to the sustainability of the building. The distributed technical equipment allows the individual connection of modules, which can be adjusted according to changing scientific requirements and hence allows various utilization scenarios. In this paper the technical challenges are described from the point of view of the steel contractor Christmann

No short description available.

No short description available.