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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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ECCS news: Steel Construction 4/2017Steel Construction4/2017367-369ECCS news

Kurzfassung


Event:
Next ECCS training course on cold-formed steel structures
Steel Bridges 2018

Further ECCS news:F European Steel Design Awards 2017 announced!
ECCS Annual Meetings: 12-14 September 2017, Copenhagen, Denmark
Charles Massonnet Award 2017

In memoriam: Bent Johansson
Jan Brekelmans

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Inhalt: UnternehmerBrief Bauwirtschaft 4/2017UnternehmerBrief Bauwirtschaft4/2017Inhalt

Kurzfassung

Keine Kurzfassung verfügbar.

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Schalk, GüntherUnd täglich grüßt der Feldhamster ..UnternehmerBrief Bauwirtschaft4/20171Editorials

Kurzfassung

Keine Kurzfassung verfügbar.

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Ernst & Sohn (Hrsg.)Gesamtausgabe UBB 4/2017UnternehmerBrief Bauwirtschaft4/20171-20Gesamtausgabe

Kurzfassung

Komplette Monatsausgabe.

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Kurz informiert: UnternehmerBrief Bauwirtschaft 4/2017UnternehmerBrief Bauwirtschaft4/20172Kurz informiert

Kurzfassung

BVMB fordert besseres Wohnungsbauklima
Neuregelungen: Licht und Schatten für den Bau
Keine Bremse bei ÖPP-Projekten

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Schneider, Christoph Th.Notfall am Bau: Wenn der Chef in der Firma plötzlich ausfälltUnternehmerBrief Bauwirtschaft4/20173-8Berichte

Kurzfassung

Alle sind ersetzbar - außer man selber. Dies sehen die meisten Menschen auch im beruflichen Alltag so, mittelständische Bauunternehmer bilden keine Ausnahme. Der Laden läuft, man ist noch keine 80, man fühlt sich fit. Außerdem war medizinisch bis auf alle fünf Jahre mal eine Grippe noch nie etwas. Und seitdem hat man ohnehin keine Arztpraxis mehr von innen gesehen. Plötzliche Ausfälle - längerfristig oder für immer - das trifft nur die Anderen. Entsprechend selten liegen Pläne für einen plötzlichen Ausfall vor. Warum diese erforderlich sind und wie die Ausgestaltung erfolgt, zeigt der weitere Beitrag auf. Leider werden nämlich nicht selten insbesondere mittelständische Bauunternehmen völlig überrollt und überfordert, wenn der Chef als zentrale Figur des Betriebs plötzlich ausfällt - sei es durch eine schwere Krankheit, durch einen Unfall oder gar durch einen überraschenden Todesfall.

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Grollmann, SaschaOperation am offenen Herzen der RuhrgebietsschlagaderUnternehmerBrief Bauwirtschaft4/20179-11Berichte

Kurzfassung

Als zentrale Hauptverkehrsader des Ruhrgebiets nimmt die A40 den überregionalen Verkehr, den Transitverkehr und den Verkehr zwischen den Ruhrgebietsstädten sowie den dortigen innerörtlichen Verkehr auf. Dabei stößt das Autobahnnetz im Bereich Bochum mit bis zu 100.000 Fahrzeugen pro Tag bereits seit Längerem an seine Belastungsgrenzen. Mit dem Ausbau der A40 von vier auf sechs Spuren und dem direkten Anschluss an den Donezk-Ring (A448) im Bereich Bochum-Stahlhausen sowie dem Umbau der Wattenscheider Straße wurden die Kapazitäten zur Aufnahme der enormen Verkehrsströme in diesem Abschnitt erweitert.

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Buchungsfehler: keine verdeckte GewinnausschüttungUnternehmerBrief Bauwirtschaft4/201712Berichte

Kurzfassung

Findet ein Steuerprüfer heraus, dass eine GmbH oder AG eine Vermögensminderung erleidet oder eine Vermögensmehrung verhindert wird und die Ursachen gesellschaftsrechtlich sind, setzt das Finanzamt eine verdeckte Gewinnausschüttung fest. Doch kann nachgewiesen werden, dass ein Buchungsfehler vorliegt, löst das keine verdeckte Gewinnausschüttung aus.

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Steuertelex: Kurz gemeldetUnternehmerBrief Bauwirtschaft4/201712Berichte

Kurzfassung

Keine Kurzfassung verfügbar.

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Schalk, GüntherAktuelles aus der RechtsprechungUnternehmerBrief Bauwirtschaft4/201713-14Berichte

Kurzfassung

Gestörter Bauablauf - was bekommt die Baufirma?
Schäden müssen nicht von Abbrucharbeiten herrühren
Nicht jeder Mangel ist ein Mangel...

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