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WIEGEL-Gruppe Gewinner des nationalen EMAS-Award 2017Stahlbau4/2017314Firmen und Verbände

Kurzfassung

Keine Kurzfassung verfügbar.

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Rotter, John MichaelShell buckling transformed: Mechanics, design processes and their inter-relationStahlbau4/2017315-324Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
This paper, in honour of Professor Herbert Schmidt, provides a brief description of two parallel but connected historical developments in the field of the buckling of thin metal shells, an area in which Professor Schmidt has made very significant contributions over the last four decades.
The developments in shell buckling mechanics have been enormous over the last century, in addressing challenging practical problems and in changing from difficult mathematics to universal access for competent engineers. The second development has been in design calculations for practising engineers, moving from crude empiricism based on simple tests into a complete framework that can house all computational predictions in a structured manner, permitting very complex problems to be fully characterised. These two fields are quite separate, especially in the early part of the 20th century, and still lie somewhat apart, but the problems encountered in practical engineering continue to influence the development of shell buckling mechanics, whilst the conceptual framework for practical design is evolving to accommodate the most complex of findings in structural mechanics.

Schalenbeulen im Wandel: Mechanik, Konstruktionsbemessungen und deren Wechselbeziehung.
Diese Arbeit zu Ehren von Professor Herbert Schmidt versucht, eine kurze Beschreibung von zwei parallelen, aber miteinander verknüpften historischen Entwicklungen auf dem Gebiet des Beulens dünner Metallschalen zu geben, für das Professor Schmidt in den letzten vier Jahrzehnten einen bedeutenden Beitrag geleistet hat.
Die Entwicklung der Schalenbeulmechanik ist im letzten Jahrhundert enorm gewesen, wenn es um herausfordernde praktische Probleme und um den Wechsel von schwieriger Mathematik zu universellem Zugang für kompetente Ingenieure geht. Die zweite Entwicklung basiert auf Konstruktionsberechnungen für praktizierende Ingenieure, die von einem groben Empirismus auf der Basis einfacher Tests zu einem vollständigen konzeptionellen Rahmen führt, der alle Resultate der Berechnungen integriert und sehr komplexe Probleme vollständig beschreibt. Diese beiden Felder waren vor allem in der ersten Hälfte des 20. Jahrhunderts völlig getrennt und liegen immer noch etwas auseinander, aber die Probleme der praktischen Technik beeinflussen weiterhin die Entwicklung der Schalenbeulmechanik, während sich der konzeptionelle Rahmen für die praktische Gestaltung um die komplexesten Befunde der Strukturmechanik entwickelt.

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Höhere Sicherheit durch neue AufzugnormStahlbau4/2017324Aktuell

Kurzfassung

Keine Kurzfassung verfügbar.

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Knödel, Peter; Ummenhofer, ThomasRegeln für die Berechnung von Behältern mit der FEMStahlbau4/2017325-339Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
Kommerzielle FE-Pakete sind zunehmend in den Ingenieurbüros verfügbar. Durch ihre Universalität verleiten sie dazu, auch dann zur Bemessung von Behältern verwendet zu werden, wenn der anwendende Ingenieur keine Erfahrung mit händischen Festigkeits- und Stabilitätsnachweisen bei Schalentragwerken hat.
Die Autoren versuchen mit diesem Artikel anhand von wenigen, strukturierten Grundregeln aufzuzeigen, welche Anforderungen an ein Modell und dessen Dokumentation zu stellen sind, so dass fachliche Richtigkeit und die erforderliche Nachvollziehbarkeit der Ergebnisse gegeben sind. Dazu wird vorab die in der Tragwerksplanung erforderliche Abstraktion diskutiert. Ebenso wird dafür plädiert, sich im Zweifelsfall für eine Handrechnung zu entscheiden, da dies möglicherweise deutlich weniger Aufwand bedingt, als eine fachgerecht dokumentierte FE-Berechnung.
Im Einzelnen werden Hinweise zur Modellierung der globalen Struktur sowie von Imperfektionen, Werkstoffeigenschaften, Schweißnähten und Lasten gegeben. Unterschiedlich aufwändige Möglichkeiten des Stabilitätsnachweises werden gezeigt. Besonderes Augenmerk wird auf eine behältergerechte Dokumentation gelegt, die ein Trennen der Spannungsausgabe in Membran- und Biegeanteile sowie in Meridian- und Breitenkreisrichtung erfordert. Schließlich werden exemplarisch drei Anwendungsbeispiele aus der industriellen Praxis gezeigt.

Rules for the analysis of tanks and silos using FEA.
Commercial FEA packages became increasingly wide spread in design offices. Being general purpose software, these packages may easily be used to model a tank or a silo by an engineer, who might not be sufficiently experienced to do proper strength and stability checks by hand. Thus, the authors see very often FE-based design, which does not meet the state of the art.
This was the motivation for the present article. Based on the needs of practical design of a steel or aluminium tank or silo, rules are given for the application of the finite element method. These include general considerations about deriving a structural model. As well, hints are given as to when a hand calculation (DBF = design by formulae) could be less time consuming than a FEA. For practical application of FEA, issues are covered like modelling and meshing of the global structure, modelling of imperfections, material properties, welds and loads. The specific needs of documentation for shell structures is discussed, i. e. splitting the obtained stresses in membrane and bending and in meridional and circumferential parts. Finally, three examples of industrial applications are described shortly.

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Hautala, Kirsi; Järvenpää, Matti-Esko; Pulkkinen, PekkaDigitalization transforms the construction sector throughout asset's life-cycle from design to operation and maintenanceStahlbau4/2017340-345Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
The construction industry is well known for falling behind in the implementation of information technologies. Many digital technologies are, however, applicable throughout the entire value chain, and the use of industrialized construction is rapidly increasing with a view to improving planning, design, construction, assembly, operation and maintenance. Different technologies have changed the engineering and construction processes drastically, and the rate at which change is taking place is generally agreed to be accelerating. This article presents four international case studies that exemplify the utilization of information modeling in bridge design projects. Information modeling is more than just a new technology - it is a new way of working which has the power to totally transform the design and construction industry.

Die Digitalisierung verwandelt den Bausektor über den gesamten Lebenszyklus von der Bemessung bis zum Betrieb und Wartung.
Die Nutzung moderner Informationstechnologien ist in der Bauindustrie weniger weit verbreitet als in anderen Industriezweigen. Viele digitale Technologien sind über die gesamte Wertschöpfungskette verfügbar und werden verstärkt verwendet, um Planung, Konstruktion, Ausführung, Überwachung und Instandhaltung stetig zu verbessern und zu vereinfachen. Verschiedene Technologien haben den Planungs- und Bauablauf drastisch verändert, wobei der Fortschritt immer schneller voranschreitet. Dieser Artikel stellt vier internationale Fallstudien vor, die exemplarisch die Verwendung von Building Information Modelling (BIM) am Beispiel von Brückenbauprojekten zeigen. BIM ist nicht nur eine neue Technologie - es ist eine komplett neue Art des Arbeitens, die die Planungs- und Ausführungsindustrie komplett verändern kann.

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Winterstetter, Thomas; Toth, Agatha; Sobek, Werner; Baur, Marco; Graser, KonradNational Museum of Qatar - Stahlbau, Gebäudehülle und 3D-BIM in höchster KomplexitätStahlbau4/2017346-350Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
Im Zuge des Ausbaus von Doha, der Hauptstadt von Katar, zu einem weltweiten Finanz-, Kultur- und Tourismuszentrum entstand auf der Grundlage eines Entwurfs von Atelier Jean Nouvel (AJN) der Neubau des Nationalmuseums (National Museum of Qatar, NMoQ). Das unverwechselbare dreidimensionale Design und die Größe des Projekts stellten höchste Anforderungen an Planung und Installation des Haupttragwerks und der Gebäudehülle.

National Museum of Qatar - Super-complex steel structures, envelope and 3D BIM.
Doha, the capital of Qatar, is developing fast towards a global hub for finance, culture and tourism. The new flagship, the National Museum of Qatar (NMoQ), is currently being completed based on a design by Atelier Jean Nouvel, Paris. The iconic three-dimensional geometry and the size of the project were extremely challenging for both the design and the works on site.

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Lange, Holger; Elberg, ChristianEntwicklung von weichen Türmen für Windenergieanlagen - SofttowerStahlbau4/2017351-356Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
In der Windenergie übernimmt der Turm eine immer wichtigere Rolle, da er mit dem Fundament zusammen für bis zu 45 % der Gesamtkosten verantwortlich ist. Für weitere Ertragssteigerungen werden in Zukunft Türme bis auf 160 m anwachsen. Um dem immer weiter wachsenden Kostendruck in der Windenergie entgegenzuwirken, werden Türme entwickelt, die sehr weich ausgelegt sind und sich gezielt im Resonanzbereich der drehenden Windenergieanlage (WEA) befinden. Hierdurch übernimmt der Turm eine Schlüsselrolle bei der Entwicklung der Anlagensteuerung und der damit einhergehenden Lasten. In diesem Aufsatz wird beschrieben, wie der weiche Turm mit der Windenergieanlage zusammen als eine Einheit die zukünftigen Windenergieanlagen mit bestimmen wird. Es werden die aeroelastischen Einflüsse und die damit verbundenen positiven aerodynamischen Dämpfeffekte in Zusammenhang gebracht und untersucht.

Development of soft towers for wind energy plants - Softtower.
The tower plays an increasingly important role in the wind energy due to the fact that tower and foundation are responsible for the overall costs up to 45 %. For further yield increase the tower height will go up to 160m in the future. Soft towers, designed purposefully with their natural frequency in the area of resonance of the rotor, will be developed to work against the growing cost pressures. This gives the tower a key role in the development of turbine control and load simulation. This article describes how the soft tower along with the turbine as a unit will determine the future wind energy plants. The aero-elastical relations and the related positive aero-dynamical damping will be implicated and analysed.

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Uhlemann, Jörg; Stranghöner, NatalieSteifigkeitskennwerte von Gewebemembranen - Standardisiert auf Produktebene und bauwerksspezifisch für die KonstruktionStahlbau4/2017357-365Fachthemen

Kurzfassung

Herrn Univ.-Prof. em. Dr.-Ing. Herbert Schmidt zur Vollendung seines 80. Lebensjahres gewidmet
Nach wie vor herrscht bei der Angabe bzw. Annahme von geeigneten Steifigkeitskennwerten für Gewebemembranen für die textile Architektur und den Zeltbau Unsicherheit unter den Materialherstellern und Tragwerksplanern. Der vorliegende Beitrag diskutiert mögliche Methoden für eine standardisierte Bestimmung von Steifigkeitskennwerten und für eine bauwerksspezifische Bestimmung für die Konstruktion. Des Weiteren werden stichprobenhaft für PVC-beschichtete Polyestergewebe dreier Festigkeitsklassen untersucht, inwieweit sich diese hinsichtlich ihrer Steifigkeitskennwerte klassifizieren lassen. Eine Klassifizierung würde eine Tabellierung ermöglichen, die dem Tragwerksplaner eine große Hilfe für die geeignete Annahme von Steifigkeitskennwerten bei der statischen Berechnung von Gewebemembrantragwerken wäre. Die vorliegenden Ergebnisse legen die Klassifizierbarkeit für die untersuchten Materialien nahe.

Stiffness parameters of fabrics - Standardized for products and project oriented for design.
For fabrics used in the field of textile architecture or tent structures, the declaration of stiffness parameters by the material supplier as well as the assumption of appropriate stiffness parameters by the design engineer is still a matter of uncertainty. The present contribution discusses possible methods for a standardized determination of stiffness parameters and for a tailored determination for specific structures. Moreover, for PVC-coated polyester fabrics of three strength classes an investigation at random is conducted analyzing whether they can be classified regarding their stiffness parameters. A classification would make a tabulation possible. This would be of great help for the design engineer for choosing appropriate stiffness parameters as input for the structural analysis of fabric structures. The presented results indicate the possibility of a classification for the investigated materials.

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Meinhardt, ChristianEinsatz von multiplen Schwingungstilger-Systemen an schlanken FußgängerbrückenStahlbau4/2017366-372Berichte

Kurzfassung

Der Einsatz von Schwingungstilgern zur Erhöhung der Gebrauchstauglichkeit von Fußgängerbrücken gehört in der Zwischenzeit zum Standard und erlaubt den Tragwerksplanern die Realisierung filigraner Bauwerke. Im Regelfall wird ein Schwingungstilger zur Reduktion von Schwingungen in einer vertikalen oder lateralen Eigenform eingesetzt, welche in einem kritischen Frequenzbereich, also dem üblichen Bereich der Schrittfrequenzen liegen. Besonders schlanke bzw. leichte Brücken weisen jedoch zahlreiche Eigenformen innerhalb dieses kritischen Bereiches auf, so dass - will man vermeiden, dass je Eigenform in dem kritischen Frequenzbereich ein Tilgersystem appliziert wird - die Konzepte zur Applikation von Schwingungstilgern angepasst werden müssen. Weiterhin weisen schlanke Fußgängerbrücken größere Verschiebungen der Eigenfrequenzen in Abhängigkeit von der Personen-Anzahl auf dem Brückendeck auf, so dass zusätzlich zu der Wirksamkeit für mehrere Schwingungsmoden auch eine entsprechend große Robustheit des Schwingungstilger-Konzepts gegenüber diesen Frequenzverschiebungen erforderlich ist. In der Vergangenheit wurden multiple Schwingungstilger-Systeme vornehmlich mit dem Ziel einer Erhöhung der Wirksamkeit passiver Systeme bei stochastischer Anregung untersucht [1], [2]. Da die dynamische Schwingantwort von schlanken Fußgängerbrücken bei Anregung durch Personen aufgrund der Anregung mehrerer Eigenfrequenzen sowie erzwungener Schwingungen im Bereich der Schrittfrequenz ebenfalls stochastische Züge aufweist, bietet es sich an, solche Konzepte ebenfalls auf Brückendecks zu applizieren. Der folgende Beitrag soll zunächst das typische Schwingungsverhalten schlanker Fußgängerbrücken an praktischen Beispielen demonstrieren. Basierend auf den gezeigten Effekten wird ein für Fußgängerbrücken optimiertes Konzept für Multiple Schwingungstilger (Multiple Tuned Mass Dampers - MTMD)-Systeme vorgestellt. Hierzu werden die mathematischen Grundlagen zur Optimierung erläutert und Hinweise zur Auswahl abzudeckender Frequenzbereiche sowie zur Massenaufteilung und Abstimmung dargelegt. Abschließend werden Ergebnisse numerischer Berechnungen einer Seilbrückenstruktur vorgestellt, bei denen ein spezielles Augenmerk auf die Robustheit des Systems gegenüber belastungsbedingter Frequenzverschiebungen sowie der charakteristischen Belastung durch Fußgänger gelegt wurde.

The Application of Multiple Tuned Mass Damper Systems at slender footbridges.
While for standard footbridge only a few vibration modes are within the critical footfall frequency range and hove to be considered for the dynamic design, lightweight structures dis-play multiple modes in that frequency range. Furthermore the modal masses are very little so also the smaller load components for the excitation of higher harmonic vibration modes can become significant to assess the vibration susceptibility. Various observations have been made during experimental tests of these structures and will be introduced in this contribution using the example of a canopy walk structure and a stress ribbon bridge. To understand the observed effects at such continuous dynamic systems for pedestrian loading, numerical calculations have been performed for which a similar lightweight structure has been modelled and pedestrian loading was simulated with several footfall frequencies. Similar to the experimentally investigated structures it was found that the multimodal dynamic response of the bridges strongly depends on the pedestrian loading (footfall frequency). Experimental tests have shown, that the application of a Tuned Mass Damper System to dampen only the critical mode that is within the footfall frequency range is not sufficient to reduce the multi-modal dynamic response of the lightweight bridge structures under pedestrian so the occurring accelerations remain below certain comfort levels. Therefore the concept of Multiple Tuned Mass Dampers was introduced to the bridge structure and its practicability was investigated.

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Neuer Windpark für DEW21: Bauüberwachung und InbetriebnahmeprüfungStahlbau4/2017372Firmen und Verbände

Kurzfassung

Keine Kurzfassung verfügbar.

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Aktuell: Stahlbau 4/2017Stahlbau4/2017373-374Aktuell

Kurzfassung

Christoph Kirchlechner mit Heinz-Maier-Leibnitz-Preis 2017 ausgezeichnet
Meik Schücke ist als weiterer Geschäftsführer der SEH Engineering GmbH bestellt
Deutschen Brückenbaupreis 2018 ausgelobt
Standpunktepapier zur Auffächerung der Ingenieurstudiengänge

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Aus der Forschung: Stahlbau 4/2017Stahlbau4/2017374-377Aus der Forschung

Kurzfassung

Fertigungs- und Instandhaltungsoptimierung bei Tragstrukturen von Offshore-Windenergieanlagen
Mehrdimensional energieoptimierte Gebäudehüllen in Stahlleichtbauweise für den Industrie- und Gewerbebau
Stahl mit knochenähnlichen Eigenschaften
Vollstanznietbeschichtungen für den Einsatz bei hochfesten Stahlwerkstoffen (P 832)
Vollstanznietkleben von dreilagigen Mischbaustrukturen (P 877)

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Termine: Stahlbau 4/2017Stahlbau4/2017377-378Termine

Kurzfassung

36. Stahlbauseminar
28. Deutscher Ingenieurtag
Brücken für die Zukunft
Nichtrostende Stähle - Eigenschaften und Anwendungen
31. Österreichischer Stahlbautag
Braunschweiger Brandschutz-Tage 2017
Heißbemessung - Structural Fire Engineering, 12. September 2017
Eurosteel 2017
3rd International Symposium on Connections between Steel and Concrete

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Content: Steel Construction 4/2017Steel Construction4/2017Contents

Kurzfassung

Keine Kurzfassung verfügbar.

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Stranghöner, NatalieSIROCO - Slip-Resistant Connections Made of Carbon and Stainless SteelSteel Construction4/2017265-266Editorials

Kurzfassung

Keine Kurzfassung verfügbar.

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Stranghöner, Natalie; Afzali, Nariman; de Vries, Peter; Glienke , Ralf; Ebert, AndreasOptimization of the test procedure for slip factor tests according to EN 1090-2Steel Construction4/2017267-281Articles

Kurzfassung

Slip-resistant connections are always used when slip and deformation in a bolted connection must be avoided at all costs, e.g. in radio masts and bridges. For some popular surface treatments, slip factors are given in EN 1090-2, the execution standard for steel structures. For those surface conditions not considered in EN 1090-2, the slip factor can be determined experimentally according to Annex G of EN 1090-2. By reviewing slip factor values obtained with the Annex G test procedure and reported in the literature, it becomes obvious that in most cases the slip factors achieved experimentally are not comparable for identical surface conditions. This is potentially caused by different interpretations of the Annex G slip test procedure. As the slip factor is one of the main parameters influencing the bearing capacity of slip-resistant connections, its determination should be on the safe side and not dependent on the various interpretation possibilities of the test procedure itself. For this reason, the optimization of the Annex G test procedure was thoroughly investigated in the European RFCS research project SIROCO, with the final objective being to enhance its reliability. The focus was on investigating the various test parameters such as type of preload measurement, ascertaining the possible slip planes, test speed, position of slip measurement, clamping length, preload level, evaluation of critical slip load and the performance of the extended creep test. The results achieved in these investigations have already been partly implemented in the revision of the current draft version of EN 1090-2.

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de Vries, Peter; Nijgh, Martin; Veljkovic, MilanDetermining the preload in preloaded bolt assemblies in existing steel structuresSteel Construction4/2017282-286Articles

Kurzfassung

Preloaded bolts are used to achieve slip-resistant shear connections. The actual preload force in each bolt has a direct influence on the fatigue and slip resistance of the connection. The strain gauge method is examined for practical assessment of the actual preload because its use is no longer limited by the demands on adhesive curing conditions. The main objective of the paper is to describe how measured strain in the bolt shank and statistical variation of the nominal mechanical and geometrical properties of the bolt are used to determine the actual bolt preload without calibrating every single bolt. The calibration factors established by laboratory and in situ measurements exhibit rather small scatter. The minimum bolt preload required is achieved with a 95 % probability of being exceeded in a bolted connection on a Dutch highway bridge (Middachterbrug).

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Kolstein, Henk; Li, Jingbin; Koper, Axel; Gard, Wolfgang; Nijgh, Martin; Veljkovic, MilanBehaviour of double shear connections with injection boltsSteel Construction4/2017287-294Articles

Kurzfassung

The RFCS project SIROCO (2014-17) included research on the further development and optimization of double shear connections with injection bolts to achieve slip- and creep-resistant bolted connections considering various influencing parameters. The type of resin, the curing condition of the resin, the geometrical and mechanical characteristics of the connection and the type of loading were studied. Results showed, for example, that of the five epoxy resins investigated, only RenGel SW404 + HY2404 (Araldite) fulfils the requirements given in Eurocode 3. A bearing stress of 175 MPa is safely allowable in the long-term without exceeding imposed deformation limits.

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Ebert, Andreas; Dörre, Maik; Glienke, RalfBehaviour of lockbolts in slip-resistant connections for steel structuresSteel Construction4/2017295-309Articles

Kurzfassung

HV bolts are often used for safe and durable connections in steel structures. However, this well-known and established bolting system has some disadvantages. Those include the scattering of the initial preload by the torque-controlled tightening method and the risk of self-loosening during fatigue loads due to lateral displacement of the components in connections with high loads. In this respect, the lockbolt technology has some advantages regarding the initial preload and loss of preload; both will be discussed in detail in this paper. The technology was invented in the 1940s and is mainly used in automotive, aviation, truck, trailer, rail, bus, agriculture, mining and military applications. Its use in structural steelwork, and especially for slip-resistant connections, has been mainly made possible through individual experimental investigations by users of the technology. Some applications call for its use in slip-resistant connections according to EN 1090-2 and Eurocode 3, e.g. the wind industry for new tower concepts with higher hub heights, and steel girder bridges. These connections can be subjected to fatigue and/or significant load reversal. The load-bearing capacity (or slip resistance) of a slip-resistant connection is mainly determined by the level of preload in the bolt and the coating system applied to the faying surfaces. However, the preload is determined by the type of bolt, and lockbolts can be used as an alternative bolting system. This paper describes a comparative study of HV bolts and lockbolts regarding their use in slip-resistant connections for steel structures. The design and execution of lockbolts will be presented. Investigations will be presented which compare HV bolts and lockbolts regarding the assembly preload, the slip resistance by performing slip load tests and the long-term behaviour with respect to loss of preload for maintenance-free connections. Furthermore, there is a discussion of the results of an online monitoring system for measuring the preload in HV bolts and Bobtail lockbolts in an alternative tower for wind turbines with the use of slip-resistant connections.

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Stranghöner, Natalie; Afzali, Nariman; Schedin, Erik; Pilhagen, Johan; Manninen, TimoPreload losses in stainless steel bolting assembliesSteel Construction4/2017310-318Articles

Kurzfassung

Stainless steel material is a suitable choice for modern steel constructions as it has a high resistance to corrosion combined with high material strength and ductility. Furthermore, its use leads to significant reductions in maintenance. In this frame, bolted connections made of stainless steel components become more and more important to enhance the application of stainless steel not only to small parts of steel structures but also to complex structures. Whereas non preloaded stainless steel bolted connections are already widely used, according to EN 1090-2, the application of preloaded stainless steel bolting assemblies is not allowed unless otherwise specified. If they shall be used, they shall be treated as special fasteners and a procedure test is mandatory. Also EN 1993-1-4 requires that their acceptability in a particular application has to be demonstrated from test results. These restrictions are mainly caused by two facts: firstly, the viscoplastic deformation behaviour of stainless steel which might result in not negligible preload losses in the bolting assemblies themselves and secondly, the gap of knowledge regarding suitable tightening parameters and procedures for stainless steel bolting assemblies to secure a required preload in the bolting assemblies and to avoid galling. To solve these questions, research activities have been carried out in the frame of the European RFCS-research project “Execution and reliability of slip resistant connections for steel structures using CS and SS” SIROCO. The present contribution gives an initial insight into the viscoplastic deformation behaviour of stainless steel bolting assemblies which were achieved in SIROCO which shows that preloaded bolted stainless steel connections can be treated similar to those made of carbon steel.

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Stranghöner, Natalie; Jungbluth , Dominik; Abraham, Christoph; Söderman, AndersTightening behaviour of preloaded stainless steel bolting assembliesSteel Construction4/2017319-332Articles

Kurzfassung

Preloaded bolting assemblies made of stainless steel are currently not permitted in steel structures due to the unknown viscoplastic deformation behaviour as well as the unknown tightening behaviour and tightening procedures for these kinds of bolting assemblies. Nonetheless, the construction industry wishes to carry out these types of connections in special cases, e.g. when special requirements exist with regard to corrosion resistance or for architectural reasons. Generally, the tightening behaviour of carbon steel HR and HV bolting assemblies according to EN 14399-3 and -4 cannot simply be transferred uncritically to stainless steel bolting assemblies due to several reasons. Within the scope of the European RFCS research project SIROCO, extensive investigations are currently being conducted on the tightening and preloading behaviour of EN ISO 4014 and EN ISO 4017 bolting assemblies made of austenitic and duplex stainless steels. First results from this project show that a targeted tightening of such assemblies is in principle possible. Specified preloading levels, e. g. Fp, C* and Fp, C, can be achieved with sufficient reliability using suitable lubricants. Herewith, it is possible to define feasible tightening procedures. Furthermore, it could be shown that these bolting assemblies show sufficient ductility and galling of the assemblies can be for sure avoided. The present paper provides an initial insight into the results of the project.

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Stranghöner, Natalie; Afzali, Nariman; de Vries, Peter; Schedin, Erik; Pilhagen, Johan; Cardwell, SimonSlip-resistant bolted connections of stainless steelSteel Construction4/2017333-343Articles

Kurzfassung

The use of stainless steel components can lead to a significant reduction of maintenance costs compared to a structure executed in carbon steel. Because of its high material strength, ductility and corrosion resistance stainless steels are becoming more and more popular as a construction material in both building and civil engineering structures. Consequently slip-resistant bolted connections made of stainless steel are becoming more important. Slip-resistant bolted connections are used in joints where slip is not acceptable (because they are subject to reversal of shear load or any other reason) or in joints that are subject to cyclic shear load (to improve the fatigue class of the connecting plates). Existing design codes/standards do not specify slip factors for surface treatments of stainless steel grades, the minimum values of slip factors for common surface treatments/coatings that are specified in EN 1090-2 are exclusively valid for carbon steels. One of the reasons for this is that stainless steel alloys are thought to suffer more than carbon steels from time dependent behaviour (creep and relaxation) at room temperature. This could lead to higher preload losses and consequently to lower slip factors than used for carbon steels with comparable surface treatment. However, no evidence of this can be found in literature. Creep and relaxation are stress dependant phenomena and the stresses in the components of preloaded bolted connections are locally highly non-uniform. Therefore, slip factors of different stainless steel grades have to be determined by experiments to investigate the effects of time dependant material behaviour. In this paper the results of slip factor tests on four stainless steel grades are presented and the influence of surface treatments and the preload level on the slip factor of stainless steel slip-resistant connections is discussed.

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Hradil, Petr; Chen, Anqi; Baddoo, NancyNumerical modelling of stainless steel preloaded bolted connectionsSteel Construction4/2017344-353Articles

Kurzfassung

The use of stainless steel in construction has become more popular in recent years. It is used for a wide range of structural applications in aggressive environments where reliable performance over long periods with little maintenance is required. Although structural design standards are available for stainless steel, currently there are no rules covering the design of preloaded slip-resistant bolted connections because of the lack of knowledge about their long-term viscoplastic behaviour. Viscoplastic creep and stress relaxation in the preloaded bolt assemblies will lead to a certain loss of clamping force and may cause the failure of the connection if not accounted for. This paper presents the development of material models and finite element models for bolt assemblies based on an extensive experimental study of creep, relaxation and tension effects on austenitic, ferritic, duplex and lean duplex steel plates and bars for different loading rates. These models were verified against slip tests with stainless steel bolt assemblies according to EN 1090-2 and then used in a parametric study to extend the scope of the connections investigated. Both experimental programmes were carried out in the European RFCS research project SIROCO (Execution and reliability of slip-resistant connections for steel structures using Carbon Steel and Stainless Steel) as well as finite element calculations.

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Feldmann, Markus; Schaffrath, SimonAssessing the net section resistance and ductility requirements of EN 1993-1-1 and EN 1993-1-12Steel Construction4/2017354-364Articles

Kurzfassung

In Eurocode 3 the strength functions are derived from simple engineering models, which always require a certain degree of material ductility. With regard to high-strength steels and the accuracy of the design models themselves, several problems are involved due to a lack of sound consideration of the plastification and damage process. Additionally, the current ductility requirements of EC3 obstruct the use of high-strength steels with fy > 500 MPa. Within the current revision of EC3, comprehensive investigations have been conducted to overcome these obstacles. To complement extensive experimental tests, improved numerical methods considering damage mechanics have been used to predict the real plastification and damage process for relevant details. The numerical models were validated by comparing them with experimental results. Subsequently, a parametric study was conducted to investigate the influence of strength and toughness properties separately. It could be shown that the reduction factor of 0.9 to account for the net section resistance can be omitted if cracks can be excluded. Furthermore, it became clear that a strain requirement based on the uniform elongation &egr;u is not appropriate. Moreover, it was revealed that the yield ratio fu/fy has a significant impact on the toughness requirements necessary to reach the full net section resistance. Owing to a lack of minimum upper-shelf toughness requirements in delivery standards, which would secure an appropriate inner damage resistance of the material, a substitution criterion is proposed.

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News: Steel Construction 4/2017Steel Construction4/2017366ECCS news

Kurzfassung

The Interactive Blue Book's Back
Metálica International n° 04: CMM celebrate this year its twentieth anniversary
Intercultural career-entry project is being continued

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