Beurteilung von Korrosionsschutzsystemen für Offshore‐Windenergietürme – Teil 2: Ergebnisse und Schlussfolgerungen

Im Rahmen von Auslagerungs‐ und Laborprüfungen wurde die Korrosionsschutzwirkung verschiedener, für den Schutz von Offshore‐Windenergietürmen geeigneter Systeme untersucht. Zu den untersuchten Systemen gehörten Duplexsysteme mit Zn/Al‐Metallisierung, mehrschichtige organische Systeme, ein einschichtiges organisches System, eine Zn/Mg‐Metallisierung sowie unbeschichtete Bereiche mit kathodischem Korrosionsschutz. Alle Systeme wurden an speziell gefertigten Auslagerungsprobekörpern sowie an Laborprobekörpern geprüft. Die im Labormaßstab durchgeführten Prüfungen umfassten Tauchversuche, Alterungsversuche, Versuche zur kathodischen Verträglichkeit und Messungen mittels elektrochemischer Impedanzspektroskopie. Im Teil 1 des Beitrages, veröffentlicht im Heft 4/2009, wurden Konzeption und Durchführung der Prüfungen sowie die verwendeten Probekörper und Korrosionsschutzsysteme detailliert beschrieben. Über die Ergebnisse der Prüfungen wird im Teil 2 berichtet. Assessment of corrosion protection systems for offshore wind energy towers – part 2: Results and conclusions. Based on field and on laboratory tests, the corrosion protective performance of different corrosion protection systems for offshore wind energy towers was investigated. The systems under investigation included duplex systems with Zn/Al metallization, multi‐layered organic systems, a single‐layer thick organic system, Zn/Mg metallization and cathodic protection of uncoated sections. Special field specimens and laboratory specimens were utilized in order to investigate the systems. Laboratory tests included immersion tests, ageing tests, test on cathodic compatibility and electro‐chemical impedance spectroscopy. Part 1 of the paper (Stahlbau, No. 4/2009) covererd the general experimental design and details of the experimental procedures, whereas Part 2 deals with the results of the test programme.     

Beurteilung von Korrosionsschutzsystemen für Offshore‐Windenergietürme – Teil 1: Problemstellung und Versuchsdurchführung

Assessment of corrosion protection systems for offshore wind energy towers – part 1: Introduction and test scenario. Based on field and on laboratory tests, the corrosion protective performance of different corrosion protection systems for offshore wind energy towers was investigated. The systems under investigation included duplex systems with Zn/Al metallization, multi‐layered organic systems, a single‐layer thick organic system, Zn/Mg metallization and cathodic protection of uncoated sections. Special field specimens and laboratory specimens were utilized in order to investigate the systems. Laboratory tests included immersion tests, ageing tests, test on cathodic compatibility and electro‐chemical impedance spectroscopy. Part 1 of the paper covers the general experimental design and details of the experimental procedures, whereas Part 2 deals with the results of the test programme.     

Ergebnisse einer Evaluierung von Energiekonzepten für Bürogebäude und Schlussfolgerungen für die Energieeffizienz und das Raumklima

Evaluation of energy concepts for office buildings – results and conclusions for energy efficiency and indoor climate. Office buildings have been in the public spotlight and subject to intensive scientific research since the 1970s. The trend towards extensively glazed façades over the last 15 years added a degree of urgency to the need for research into energy efficiency and occupant comfort. The associated public scolding of architects and engineers and the – in some cases questionable – technical discussions revealed information deficits. The research project entitled “Evaluation of energy concepts for office buildings (EVA)” aimed to reduce this information deficit. Overall, 19 office buildings were examined.     

Experimentelle und numerische Untersuchungen von Knotenverbindungen für Tripods von Offshore‐Windenergieanlagen

Experimental und numerical investigations for tripod joints of offshore‐structures. This paper summarises fatigue tests on Y‐joints to estimate the influence of a post weld treatment method called Ultrasonic Impact Treatment (UIT). With this method the fatigue resistance could be increased significantly. Furthermore tubular joints of tripods are analysed with numerical simulations to judge these welded joints with the hot‐spot‐concept. The stress concentration factor for the treated weld toe geometry was determined numerically using submodel analysis. Finally a comparison between welded and cast iron joints is carried out for the fatigue limit state under consideration of experimental results.     

Gründung von Offshore‐Windenergieanlagen – Entscheidungshilfen für Entwurf und Bemessung

Foundations for offshore wind energy converters – Recommendations for concept and design. About 25% of the capital costs of an offshore wind farm are required for fabrication and installation of foundation structures. This relatively large percentage results from the fact that foundations have to be designed for the local site conditions within the wind farm. The possibilities for pre‐fabrication onshore are limited. Consequently, the design of safe but economic foundations is of great importance for the cost‐effectiveness of the whole wind farm. Within the present paper various foundation concepts adopted from conventional offshore engineering are compared and the selection of an appropriate foundation in respect to the conditions in North and Baltic Sea is discussed. The analysis shows that not in any case all of these foundation concepts are equally suitable. The most important criteria are the soil conditions at the respective location and the resulting fabrication and installation efforts.     

Schweißen von Feinkornstählen und deren Eignung für Offshore‐Windenergieanlagen

Welding of fine grain structural steels and there suitability for offshore wind power plants. The investigations show that the high requirements on the mechanical values of a welded joint can be fulfilled by economical process versions of submerged arc welding. The submerged arc tandem twin welding process is predestined for the production of WPP (wind power plant) because of the high value of melting rate and the small expenditure of equipment. The used filler metal is suitable for the production of welded joints with mechanical values which fulfil safely the requirements. Steel grades produced by the TMCP becoming more and more popular for the producers of wind power generator tower because of there better processing and working properties. In comparison with normalized steel grades the TMCP steel grades have e.g. a lower carbon equivalent and higher toughness properties. With increasing clarity of the standards and of the working direction of the European offshore wind power industry further challenges will be appear for the producers of steel, wind power plants and welding equipment. A close cooperation between al partners is inalienable in that case.     

DIN 1052:2004 – Neue Grundlagen für Entwurf,Berechnung und Bemessung von Holzbauwerken – Teil 1: Material‐ und Werkstoffverhalten

DIN 1052:2004 – New basics for design, calculation and dimensioning of timber structures. Part1: Material behaviour. This article discribes the material properties of timber as a biological material, which is growing in the forest. Timber in structural dimension is a nonhomogeneous material, which contains growth defects in the form of knots, nonparallel fibre orientation etc. Concluding from that the nonhomogeneous character, the influence of defects on the strength properties the importance of moisture content, the strength grading of timber, the principles of durability will be described.     

Stahlbeton‐Verbundkonstruktionen – Ein Bemessungskonzept für schubbeanspruchte Fugen. Teil 2: Normative Empfehlungen für Neubau und Revitalisierungsmaßnahmen

R/C Composite Constructions – A Design Concept for Shear Loaded Joints – Part 2: Normative Recommendations for New Building and Retrofit Measures In the modern engineering practice composite constructions are often used. This constructions consisting of prefabricated R/C components and in situ concrete are marked by the interaction of concrete interfaces with different age and different strength. With various examinations will be show, that the present designing practice and the distribution of reinforcement is not effective and leads to high reinforcement concentrations in uncritical joint sections and also to an unbalanced reinforcement along the joint. This paper is divided into 2 parts: Part 1 summarizes the state‐ofthe‐ art, a special structural model and important results. A design concept, continued in part 2, will be presented for the practical use according to European standard EC 2 which enables the differentiation between narrow and broad bond surfaces for the first time. Additional, the new concept considers the non‐rigid bond and also decisive parameter in a subtly differentiated, nearly realistic and bearing structure referred way.