@inproceedings{JaegerCanasPasternak, author = {J{\"a}ger-Ca{\~n}{\´a}s, Andreas and Pasternak, Hartmut}, title = {Zum Tragverhalten ringversteifter Schalen unter Axialdruck}, series = {110 Jahre DASt und 21. DASt-Forschungskolloquium an der Technischen Universit{\"a}t Kaiserslautern, 6./7. M{\"a}rz 2018}, booktitle = {110 Jahre DASt und 21. DASt-Forschungskolloquium an der Technischen Universit{\"a}t Kaiserslautern, 6./7. M{\"a}rz 2018}, publisher = {Deutscher Ausschuß f{\"u}r Stahlbau DASt}, address = {D{\"u}sseldorf}, isbn = {978-3-941687-27-1}, pages = {227 -- 232}, abstract = {Ringsteifen werden typischerweise bei d{\"u}nnwandigen Tanks am Mantel befestigt, um auch f{\"u}r starken Wind und/oder Unterdruck eine ausreichende Beulsicherheit sicherzustellen. Eine Vielzahl an Ver{\"o}ffentlichungen zum Thema Ringsteifen besch{\"a}ftigt sich ausschließlich mit den vorher genannten Lastf{\"a}llen. Dagegen ist der traglaststeigernde Einfluss der Ringsteifen im Lastfall Axialdruck kaum erforscht. Experimentell wurde vor allem in den 1960er und 1970er Jahren gegen{\"u}ber unversteiften Schalen, f{\"u}r eng-ringversteifte ein erheblich verbessertes Tragverhalten nachgewiesen. Der eingeschr{\"a}nkte Parameterbereich der Untersuchungen verhindert jedoch die Anwendung der Erkenntnisse im Metallbau, wo, aufgrund der Fertigungskosten, eher wenige, daf{\"u}r kr{\"a}ftigere Ringsteifen eingesetzt werden. Der Beitrag baut auf den experimentellen Studien als Grundlage auf und erweitert die Erkenntnisse mittels numerischer Parameterstudien von eng-ringversteiften Schalen auf Kreiszylinder mit Steifenabst{\"a}nden bis zum Zehnfachen der klassischen Beulhalbwellenl{\"a}nge 1.73√rt. Es wird gezeigt, dass auch mit versteiften Schalen, bei denen der Steifenabstand gr{\"o}ßer als zwei Beulhalbwellenl{\"a}ngen ist, noch Tragf{\"a}higkeitssteigerungen gegen{\"u}ber der unversteiften Schale erreicht werden k{\"o}nnen. Erwartungsgem{\"a}ß sind die Zugewinne an Traglast bei enger versteiften Kreiszylindern am gr{\"o}ßten, wobei vor allem d{\"u}nnwandige Strukturen von der verringerten Imperfektionssensitivit{\"a}t profitieren. Die Ergebnisse, angewandt auf die Baupraxis, erlauben eine wirtschaftlichere Bemessung von Tanks und Silos mit Ringsteifen, sofern Axialdruck eine bemessungsrelevante Lastsituation darstellt. Dies ist in der Regel bei {\"u}berdachten Silos und windbelasteten Flachbodentanks der Fall. Daf{\"u}r ist kein zus{\"a}tzlicher Konstruktionsaufwand notwendig, da lediglich die ohnehin vorhandene Struktur vorteilhafter ausgenutzt wird.}, language = {de} } @inproceedings{LedeckyCiupackPasternaketal., author = {Ledecky, Lukas and Ciupack, Yvonne and Pasternak, Hartmut and Geßler, Achim and Feldmann, Markus}, title = {Reduction of Fatigue Crack Growth Rate in Compact Tension Specimens Using Adhesively Bonded CFRP-Strips}, series = {Proceedings of the METNET Seminar 2017 in Cottbus}, booktitle = {Proceedings of the METNET Seminar 2017 in Cottbus}, editor = {Virdi, Kuldeep and Tenhunen, Lauri}, publisher = {H{\"a}me University of Applied Sciences (HAMK)}, address = {H{\"a}meenlinna}, isbn = {978-951-784-794-0}, pages = {30 -- 42}, language = {en} } @inproceedings{CiupackPasternakYilmazetal., author = {Ciupack, Yvonne and Pasternak, Hartmut and Yilmaz, Emre Mehmet and Sternsdorff, Florian and Vayas, Ioannis}, title = {Hybrid Reinforcement Measures and Innovative Measurement Methods in Steel Construction}, series = {Proceedings of the METNET Seminar 2017 in Cottbus}, booktitle = {Proceedings of the METNET Seminar 2017 in Cottbus}, editor = {Virdi, Kuldeep and Tenhunen, Lauri}, publisher = {H{\"a}me University of Applied Sciences (HAMK)}, address = {H{\"a}meenlinna}, isbn = {978-951-784-794-0}, pages = {43 -- 55}, language = {en} } @inproceedings{PasternakCiupackLedeckyetal., author = {Pasternak, Hartmut and Ciupack, Yvonne and Ledecky, Lukas and Dilger, Klaus and Stammen, Elisabeth and Fischer, Vitali}, title = {Untersuchungen zum Tragverhalten und der Lebensdauer von Klebverbindungen im Stahlbau unter zyklischer Belastung}, series = {18. Kolloquium Gemeinsame Forschung in der Klebtechnik, K{\"o}ln, 27. - 28. Februar 2018}, booktitle = {18. Kolloquium Gemeinsame Forschung in der Klebtechnik, K{\"o}ln, 27. - 28. Februar 2018}, publisher = {DECHEMA}, address = {Frankfurt am Main}, pages = {62 -- 64}, language = {de} } @misc{GarifullinLaunertHeinisuoetal., author = {Garifullin, Marsel and Launert, Benjamin and Heinisuo, Markku and Pasternak, Hartmut and Mela, Kristo and Pajunen, Sami}, title = {Effect of welding residual stresses on local behavior of rectangular hollow section joints. Part 1 - Development of numerical model}, series = {Bauingenieur}, volume = {93}, journal = {Bauingenieur}, number = {4}, issn = {1436-4867}, pages = {152 -- 159}, abstract = {Welded tubular joints are widely used in structural engineering due to their excellent resistance and stiffness in contrast to open sections, as well as simpler end preparation. Welding residual stresses that occur in these joints after the welding process can affect their structural behavior. Some recent experimental studies have shown that this effect can be considerable. This study numerically evaluates the influence of welding residual stresses on the behavior of rectangular hollow section T joints. The paper consists of two parts. Part I develops and validates a finite element model for the joints directly taking into account welding residual stresses by means of an upstream thermomechanical simulation of the welding process. It is proven that particular attention needs to be paid to the discretization of the model, the material properties and the adequate description of the weld heat input. The validation with experimental results shows that the developed numerical model properly captures the local structural behavior of tubular joints and can be efficiently used for further investigations. Part II employs the constructed model to investigate the effect of welding residual stresses on the resistance and initial stiffness of the considered joints.}, language = {en} } @misc{PartovPasternakPetkovetal., author = {Partov, Doncho and Pasternak, Hartmut and Petkov, Milen and Nikolov, Radoslav and Dimitrova, Antoaneta}, title = {About the history of orthotropic bridge decks}, series = {Annual of the University of Architecture, Civil Engineering and Geodesy, Sofia}, volume = {51}, journal = {Annual of the University of Architecture, Civil Engineering and Geodesy, Sofia}, number = {4}, issn = {1310-814X}, pages = {295 -- 311}, abstract = {Тhe development of steel bridges after the WWII is characterized by new constructive forms like: steel roadway closed sections, new static systems considering the roadway as a plate rather than a beam grid, new computational methods covering rod statics and statics of continuum, and determining the internal forces of the roadway as internal forces of an orthotropic plate. Moreover, the main girders, the roadway and the horizontal links connect statically and constructively in a whole monolithic structure. Thus, the construction follows better the real distribution of internal forces in steel structure. Loading possibility of high-quality steel material is well used, by which the economic effect of the construction increases significantly compared to the riveted old bridges. The application of this theory in Bulgaria in the period 1976 - 1992 allowed the Bulgarian bridge construction to build several unique by their size steel road bridges of steel orthotropic decks.}, language = {en} } @misc{GarifullinLaunertHeinisuoetal., author = {Garifullin, Marsel and Launert, Benjamin and Heinisuo, Markku and Pasternak, Hartmut and Mela, Kristo and Pajunen, Sami}, title = {Effect of welding residual stresses on local behavior of rectangular hollow section joints. Part 2 - Parametric studies}, series = {Bauingenieur}, volume = {93}, journal = {Bauingenieur}, number = {5}, issn = {1436-4867}, pages = {207 -- 213}, abstract = {Welding residual stresses that occur in tubular joints after the welding process affect their structural behavior. To ensure that these stresses do not negatively act on the load-bearing capacity of joints, their influence should be carefully investigated. This paper represents the second part of a study that numerically evaluates the structural behavior of rectangular hollow section T joints taking into account welding residual stresses. The finite element model developed in Part 1 is now used to evaluate their effect on the resistance and initial stiffness of tubular joints. The conducted parametric analyses show that welding residual stresses have a positive influence of 1-19 \% on the plastic resistance of tubular joints and insignificantly reduce their initial stiffness. At the same time, the behavior of the considered joints is found not to depend on the welding sequence.}, language = {en} } @misc{LiLaunertPasternak, author = {Li, Zheng and Launert, Benjamin and Pasternak, Hartmut}, title = {Application of the stochastic finite element method in welding simulation}, series = {Welding in the World}, volume = {62}, journal = {Welding in the World}, number = {5}, issn = {0043-2288}, doi = {10.1007/s40194-018-0596-4}, pages = {905 -- 912}, abstract = {Due to the uncertain microscopic structure of the material, the strength of the material exhibits strong randomness. This randomness results in uncertain response of the structure in the sequentially coupled thermal-mechanical analysis by welding simulation. Because of the limitations of deterministic welding simulation, the stochastic finite element method with random field will be introduced into the welding simulation, so that the welded structure can be more accurately calculated in the stability and reliability structural analysis. Particularly, it is necessary to propose reasonable distributions of residual stress from welding simulations based on statistical and reliability theories. This paper is intended to implement the stochastic finite element method in the welding simulation using a general-purpose simulation program and to demonstrate the potential of the proposed approach. Furthermore, the statistical distribution function of the welding simulation response is obtained by maximum entropy fitting method. Then, a numerical example is presented by the proposed method.}, language = {en} } @inproceedings{GarifullinLaunertHeinisuoetal., author = {Garifullin, Marsel and Launert, Benjamin and Heinisuo, Markku and Pasternak, Hartmut and Mela, Kristo and Pajunen, Sami}, title = {Effect of Welding Residual Stresses on Behavior of Tubular T Joints}, series = {17th International Conference on Computing in Civil and Building Engineering}, booktitle = {17th International Conference on Computing in Civil and Building Engineering}, pages = {8}, abstract = {Welded tubular joints are widely used in structural engineering due to their excellent resistance and stiffness, as well as simple connection. However, the welding process induces residual stresses in the welding area that can affect the structural behavior of joints. Currently very few papers investigate welding residual stresses in relation to tubular joints. This paper develops a finite element model of rectangular hollow section T joints considering welding residual stresses. Attention is paid particularly to welding sequences. The developed model is used to evaluate the effect of welding residual stresses on the resistance and initial stiffness of tubular joints. The results show that welding residual stresses increase the plastic resistance of rectangular hollow section joints under in-plane bending and axial brace loading.}, language = {en} } @inproceedings{ZivaljevicLuxorPasternak, author = {Zivaljevic-Luxor, Natasa and Pasternak, Hartmut}, title = {Roofs for archaeological sites integration into public space of metropolitan area}, series = {International Scientific Conference, Nis, Serbia, 31.08-01-09.2018}, booktitle = {International Scientific Conference, Nis, Serbia, 31.08-01-09.2018}, pages = {10}, language = {en} } @inproceedings{JaegerCanasPasternak, author = {J{\"a}ger-Ca{\~n}{\´a}s, Andreas and Pasternak, Hartmut}, title = {On the buckling behavior of ring-stiffened shells under axial compression}, series = {8th International Conference on Thin-Walled Structures, ICTWS 2018, Lisbon, Portugal, July 24-27, 2018}, booktitle = {8th International Conference on Thin-Walled Structures, ICTWS 2018, Lisbon, Portugal, July 24-27, 2018}, pages = {13}, language = {en} }