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Stranghoner N.,University of Duisburg - Essen | Schiborr M.,University of Duisburg - Essen | Glienke R.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Wanner M.-C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Ulbrich D.,Deutsches Institute For Bautechnik
Stahlbau | Year: 2013

Slip-resistant connections in steel structures permit bolted connections with low slip and deformation, which are mainly used in structures, in which deformations of the connections would limit the serviceability of the structures. Typical applications can be found in radio masts, bridges and towers of wind turbines, which are loaded by fatigue. Essential characteristics of these connections are the slip factor and the preload in the bolts. The new execution standard for steel structures, DIN EN 1090-2, provides in contrast to DIN 18800-7 the possibility of considering different surface treatments by various classes and with Annex G, it provides a detailed test method to determine the slip factor taking into account possible creep effects. The differences in the testing methodology in comparison to the TL/TP-KOR- Stahlbauten are in the details and can lead to unfavourable slip factors. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


Ulbrich D.,Deutsches Institute For Bautechnik | Primke-Engel R.,Ingenieurburo Primke Engel | Blunk C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Glienke R.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik
Stahlbau | Year: 2013

Mechanical joints in metallic light weight structures. Construction is not possible without joining single parts to components and at the end to the final structure. There exist multifarious kinds of connections whose suitability mainly depends on the characteristic of raw material the structural parts are made of. This article especially deals with joints in metallic light weight structures. Beside the typical connections in metal structures like welding, bolting and riveting in metallic light weight structures further kinds of connections can be found like standing seam, clinch, punch rivet or cartridge fired pin connections. Describing all these single methods would go beyond the scope of this article. That is why only the predominant part of all connections with so called pencil-shaped fastening elements like screwed connections, blind riveted connections and connections with cartridge fired pins will be dealt with. Furthermore the scope of application will be shown, advantages and disadvantages will be compared, the determination of characteristic values or resistance will be shortly explained and advices for calculation and execution will be given. © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


Glienke R.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Ebert A.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Wanner M.-C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Kupzok A.,TUV SUD
Stahlbau | Year: 2015

Moderne Windenergieanlagen ermöglichen mit hohen Nabenhöhen eine wirtschaftliche Energiegewinnung an windschwächeren Standorten sowie in komplexem Terrain oder Waldgebieten. Große Nabenhöhen stellen große Herausforderungen an die Leistungsfähigkeit der Türme, die für den Betrieb der Anlage bestimmte statische und dynamische Eigenschaften erfüllen müssen. Dabei erreicht die Machbarkeit von konventionellen, geschweißten Stahlrohrtürmen technische sowie wirtschaftliche Grenzen und es kommen alternative Turmkonzepte zum Einsatz. Für alternative Turmkonzepte aus Stahl bringen gleitfeste Verbindungen (GV-Verbindung) zahlreiche Vorteile, werfen aber auch neue Fragestellungen auf. Die Tragfähigkeit der GV-Verbindung ist neben der Haftreibungszahl für die Reiboberflächen von der eingebrachten Vorspannkraft abhängig. Im Rahmen der geplanten Lebensdauer einer Windenergieanlage ergeben sich für die GV-Verbindungen Vorspannkraftverluste, die geeignet berücksichtigt werden müssen. Die derzeitigen Bemessungsregeln im Stahlbau erlauben jedoch keine rechnerische Ermittlung dieser Verluste, so dass ein Wartungsaufwand unumgänglich ist. Im diesem Artikel wird in Anlehnung an die VDI-Richtlinie 2230 für Schraubenverbindungen im Maschinenbau ein verbesserter Bemessungsansatz für GV-Verbindungen im Stahlbau präsentiert, der die Nachweismöglichkeit mit einer verbleibenden Vorspannkraft abzüglich etwaiger Vorspannkraftverluste bietet. Weiterhin werden vergleichende Schwingfestigkeitsuntersuchungen an GV-Verbindungen mit gebohrten und gestanzten Löchern vorgestellt. Es wurde nachgewiesen, dass sich bei gleitfester Lastübertragung keine negativen Effekte auf die Ermüdungsfestigkeit durch Stanzen ergeben. Auf Basis dieser Untersuchungen konnte eine Typenprüfung für einen wartungsfreien Stahlschalenturm ausgestellt werden, der aus mit GV-Verbindungen gefügten Stahlplatten besteht. Requirements for mechanical joining for application in the wind turbine towers for large hub height made of steel. Modern wind turbines with high hub heights enable an economical energy production for locations with lower wind speed, complex terrain or in forests. High hub heights result in high requirements for the performance of turbine towers. For power production, the towers have to feature distinct static and dynamic properties. The feasibility of conventional, welded tubular steel towers faces technical and economical limits and alternative tower concepts are applied. For alternative steel towers concepts, friction connections with preloaded bolts have several advantages, but also raises new questions. The load bearing capacity of a friction connection depends on the coefficient of static friction and the applied pretension. During the turbine lifetime, the friction connection will be subject to a loss of pretension that needs to be considered. According to current design standards for steel constructions, the loss of pretension cannot be included in the design phase, but must be accounted for by means of maintenance. This article presents an advanced design method for friction connection in steel constructions that is based on the VDI guideline 2230 for bolted connections in machinery structures and includes a possibility to consider loss of pretension. In addition, friction connections with drilled and punched holes are considered. It can be shown, that for preloaded friction connections, the punching of holes leads to no adverse effects for fatigue resistance. On the basis of this design method, it was possible to issue a type approval for a maintenance free steel shell tower that consists of steel plates, which are joined by friction connections. © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source


Glienke R.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Blunk C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Denkert C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik | Wanner M.-C.,Fraunhofer Anwendungszentrum Grossstrukturen in der Produktionstechnik
Stahlbau | Year: 2015

A large number of mechanical joints for steel structures is generated with conventional bolts. Still, this proven joining technology has some significant disadvantages. These include the big scattering of inserting the preload using the torque-tightening method, the risk of self-loosening by cyclic loads causing a cross movement of the components as well as the low fatigue resistance for axial loads. The lock-bolt technology was already invented in the 1930s and mainly used for the aviation and space industry in support of its evident advantages. Due to demands from different industrial markets, like aviation, truck, trailer, rail, bus, agriculture, mining, military and steel construction industry, the lock-bolt technology was further developed and applied. Its application, particularly in the mechanical engineering sector, was mainly possible due to individual investigations performed by the users of the technology. These investigations were costly but necessary due to the lack of consistent design rules, which hindered a broader implementation and the calculation of lock-bolt connections in the construction and building industry. Within the scope of several research projects funded by the AiF (German Federation of Industrial Research Associations) the Fraunhofer-Application Center for Large Structures in Production Engineering successively developed calculation rules, which will be introduced to the reader within the scope of this paper with the aim to utilise the advantages of this joining technique. Furthermore, the applicability in the building industry with general technical approvals will be exemplified and current applications demonstrated. © 2015 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

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