@inproceedings{PasternakJaegerCanas, author = {Pasternak, Hartmut and J{\"a}ger-Ca{\~n}{\´a}s, Andreas}, title = {On the axial buckling of very thin-walled cylindrical shells}, series = {Ce/papers : the online collection for conference papers in civil engineering}, volume = {1}, booktitle = {Ce/papers : the online collection for conference papers in civil engineering}, number = {2-3}, issn = {2509-7075}, doi = {10.1002/cepa.127}, pages = {868 -- 877}, abstract = {Major advances in the buckling analysis of cylindrical shells have been achieved in the last two decades. Eurocode nowadays provides rules for tanks up to r/t = 5000. However, since only few literature has become available in the past, dealing specifically with very thin walled shells in the range between r/t = 1500 and r/t = 10000, code provisions either are quite conservative or, in case of r/t > 5000, do barely exist. Employing modern construction methods, close-to perfect, very thin-walled shells can be built that are out of the scope of the design codes. Therefore, to achieve more economical designs and a better sustainability, sophisticated design tools have to be used. In this paper, modifications and extensions of the current design procedure are proposed to overcome current limitations and drawbacks. A review of experiments with a special focus on cylinders with high r/t-ratios was conducted and modified lower bound approximation curves for the knock-down factor α deduced. They were checked against representative experiments from literature. Test results recalculated using an axisymmetric imperfection to explore their equivalent imperfection depth, proved that even small imperfections drastically reduce the buckling strength. Using a parametric study, the result range of α was extended up to r/t = 10000. The design proposal could be approved and an equation for the determination of an equivalent imperfection depth that relates the dependence of α to the imperfection depth and the r/t-ratio is proposed.}, language = {en} } @inproceedings{JaegerCanasPasternak, author = {J{\"a}ger-Ca{\~n}{\´a}s, Andreas and Pasternak, Hartmut}, title = {Influence of closely spaced ring-stiffeners on the axial buckling behavior of cylindrical shells}, series = {Ce/papers : the online collection for conference papers in civil engineering}, volume = {1}, booktitle = {Ce/papers : the online collection for conference papers in civil engineering}, number = {2-3}, issn = {2509-7075}, doi = {10.1002/cepa.133}, pages = {928 -- 937}, abstract = {Material efficiency in modern tank constructions often is achieved by combining thin plates with light and heavy ring stiffeners. While the plates are designed to resist hydrostatic pressure, the stiffeners are designed against wind and external pressure. Axial buckling may occur due to high roof loads and wind since very thin plates are prone to a loss of stability. Test results in the 60s and 70s revealed that closely spaced ring-stiffeners may greatly enhance the axial buckling behavior, allowing for knock-down factors greater unity. However, until today, no design procedure is available allowing for adopting the beneficial effect of ring stiffeners under axial compression into practical design. In this paper a design procedure is proposed that closes this gap in current design codes. One outcome of the conducted literature study revealed that test results of unstiffened shells may be more closely approximated and is shortly presented. The design procedure for ring-stiffened shells was then developed from lower bound curves deduced from categorized buckling tests. The results of a parametrical study, that was conducted over a wide range of r/t-values, is presented. Imperfection depths up to 10t were examined using a stiffener spacing of one buckling half-wave. Especially highly slender stiffened cylinders benefit from ring-stiffening, showing up to 380\% strength gains. Imperfection depths proposed by the current design code were found to be too conservative.}, language = {en} } @inproceedings{PasternakZivaljevicLuxor, author = {Pasternak, Hartmut and Zivaljevic-Luxor, Natasa}, title = {Evolution of an heritage edifice from colossus in Prora to colossus of Prora}, series = {3rd International Conference on Protection of Historical Constructions}, booktitle = {3rd International Conference on Protection of Historical Constructions}, publisher = {IST Press}, address = {Lisbon}, isbn = {978-989-8481-58-0}, pages = {387 -- 388}, language = {en} } @inproceedings{StapelfeldLaunertPasternaketal., author = {Stapelfeld, Christoph and Launert, Benjamin and Pasternak, Hartmut and Doynov, Nikolay and Michailov, Vesselin}, title = {Numerische Festigkeitsberechnung einer versteiften Struktur unter Ber{\"u}cksichtigung realit{\"a}tsnaher geometrischer und struktureller Imperfektionen}, 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 = {245 -- 249}, abstract = {Die Festigkeitsberechnung von Strukturen, zum Beispiel Platten oder Schalen, mittels der Finite-Elemente-Methode geh{\"o}rt schon seit l{\"a}ngerem zum Stand der Technik. Ber{\"u}cksichtigt werden bei der Berechnung sowohl geometrische Nichtlinearit{\"a}ten als auch das nichtlineare Verhalten des Werkstoffs. Die geometrischen und strukturellen Imperfektionen werden bei der Ermittlung der Festigkeit zumeist in ausschließlich geometrischen Imperfektionen, wie bspw. Kombinationen aus Fertigungstoleranzen und den Ergebnissen von Beulanalysen zusammengefasst. Zur Rechtfertigung dieser Vorgehensweise werden die geometrischen Imperfektionen gem{\"a}ß DIN EN 1993-1-5 erh{\"o}ht. In einem Kommentar zur selben Norm findet sich ebenfalls eine Empfehlung zur Ber{\"u}cksichtigung von Schweißimperfektionen in Form von vereinfachten L{\"a}ngseigenspannungsverl{\"a}ufen. Diese werden in Abh{\"a}ngigkeit der Fließgrenzspannung des Werkstoffs bei Raumtemperatur und der Dicken der F{\"u}gepartner angenommen. Sowohl die Annahme rein geometrischer Imperfektionen als auch die Ber{\"u}cksichtigung vereinfachter Eigenspannungszust{\"a}nde, sind mit Sicherheitszuschl{\"a}gen behaftet. Durch eine realit{\"a}tsn{\"a}here Ber{\"u}cksichtigung von strukturellen und geometrischen Imperfektionen, hervorgerufen durch Schweißprozesse, kann die tats{\"a}chliche Tragf{\"a}higkeit einer Struktur wesentlich exakter bestimmt werden. Inhalt dieses Artikels ist die Anwendung eines analytisch-numerischen Hybridmodells zur Schweißimperfektionsberechnung an einer doppelt versteiften Platte und einer anschließenden Festigkeitsanalyse. Eingangs wird das analytische Modell vorgestellt und auf die grundlegenden physikalischen Zusammenh{\"a}nge eingegangen. Es folgt die Erl{\"a}uterung des Kopplungsalgorithmus zwischen analytischem Modell und der numerischen Berechnung. Angewendet an der doppelt versteiften Platte, wird ein realit{\"a}tsnaher geometrischer und struktureller Imperfektionszustand berechnet. Eine anschließende Traglastanalyse gibt Aufschluss {\"u}ber das Verformungsverhalten unter achsialer Krafteinwirkung. Zur Bewertung der Ergebnisse wird ein Modell gleicher geometrischer Abmessungen und Werkstoffkennwerte aus der Literatur herangezogen. Berechnet wurden die ersten 6 Eigenformen mittels analytischer und numerischer Modelle sowie die Last-Verformungskurven unter der Annahme unterschiedlicher geometrischer Imperfektionen. Um die Vergleichbarkeit der Ergebnisse zu sichern, wird eingangs die Lagerung des Modells sowie der Kraftangriffspunkt in L{\"a}ngsrichtung invers, durch den Vergleich der ersten 6 Beulformen sowie der Last-Verformungskurven dreier Imperfektionen, bestimmt. Darauf aufbauen wird die Last-Verformungskurve f{\"u}r einen {\"u}berlagerten Imperfektionszustand berechnet, wobei die geometrischen Imperfektionen aus den Fertigungstoleranzen abgeleitet und die strukturellen idealisiert, gem{\"a}ß DIN EN 1993-1-5, gew{\"a}hlt werden. Abschließend werden alle Last-Verformungskurven einander gegen{\"u}bergestellt. Anhand des Vergleichs kann quantifiziert werden, wie konservativ die einzelnen angenommenen Imperfektionen sind und wie sich der Verformungsverlauf darstellt, berechnet man diesen unter Verwendung realit{\"a}tsnaher geometrischer und struktureller Imperfektionen.}, language = {de} } @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} } @incollection{LoebjinskiRugPasternak, author = {Loebjinski, Maria and Rug, Wolfgang and Pasternak, Hartmut}, title = {Aktuelle Normen f{\"u}r den Bestandsbau mit Holz und beispielhafte Zuverl{\"a}ssigkeitsuntersuchungen}, series = {Holzbau im Bestand - historische Holztragwerke : Beispiele f{\"u}r substanzschonende Erhaltung}, booktitle = {Holzbau im Bestand - historische Holztragwerke : Beispiele f{\"u}r substanzschonende Erhaltung}, editor = {Rug, Wolfgang}, publisher = {Beuth Verlag}, address = {Berlin}, isbn = {978-3-410-28175-7}, pages = {162 -- 192}, language = {de} } @inproceedings{LoebjinskiRugPasternak, author = {Loebjinski, Maria and Rug, Wolfgang and Pasternak, Hartmut}, title = {Possibilities for a modification of partial safety factors for existing timber structures}, series = {World Conference on Timber Engineering, Seoul, 20 - 23 Aug 2018}, booktitle = {World Conference on Timber Engineering, Seoul, 20 - 23 Aug 2018}, pages = {7}, language = {en} } @inproceedings{PartovPasternakGrekovetal., author = {Partov, Doncho and Pasternak, Hartmut and Grekov, Petar and Nikolov, Radoslav and Dimitrova, Antoaneta}, title = {About the Theory of Orthotropic Steel Plate Established by Wilhelm Cornelius and its Application for Analysis of Two Steel Bridges With Orthotropic Decks in Varna}, series = {X Jubilee International Scientific Conference „Civil Engineering Design and Construction", Sept. 20-22, 2018, Varna, Bulgaria}, booktitle = {X Jubilee International Scientific Conference „Civil Engineering Design and Construction", Sept. 20-22, 2018, Varna, Bulgaria}, pages = {469 -- 481}, language = {en} } @inproceedings{LoebjinskiKoehlerRugetal., author = {Loebjinski, Maria and K{\"o}hler, Jochen and Rug, Wolfgang and Pasternak, Hartmut}, title = {Development of an optimization-based and practice orientated assessment scheme for the evaluation of existing timber structures}, series = {Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision}, booktitle = {Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision}, editor = {Caspeele, Robby and Taerwe, Luc and Frangopol, Dan M.}, publisher = {Taylor \& Francis Group}, address = {London}, isbn = {978-1-138-62633-1}, pages = {353 -- 360}, language = {en} } @inproceedings{StapelfeldLaunertPasternaketal., author = {Stapelfeld, Christoph and Launert, Benjamin and Pasternak, Hartmut and Doynov, Nikolay and Michailov, Vesselin}, title = {Strength Calculation of Stiffened Structures Taking Into Consideration Realistic Weld Imperfections}, series = {European Conference on Residual Stresses 2018, ECRS-10, Leuven, Belgium, 11-14th September, 2018}, booktitle = {European Conference on Residual Stresses 2018, ECRS-10, Leuven, Belgium, 11-14th September, 2018}, editor = {Seefeldt, Marc}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, isbn = {978-1-945291-88-3}, doi = {10.21741/9781945291890-39}, pages = {245 -- 250}, abstract = {The topic of this article is the application of an analytical numerical hybrid model for a realistic prediction of imperfections induced by welds. At the beginning, the analytical model, its physical basis as well as the physical interrelationships are explained. This is followed by the explanation of the coupling procedure between the analytical model and the numerical calculation. Afterwards, the coupled hybrid model is applied on the investigated stiffened curved structure for the determination of the weld imperfections. An ultimate load analysis gives information about the load carrying behavior under axial loading. The results are compared against the traditional approach using eigenmode-based imperfections. The comparison underlines the potential additional utilization of load bearing capacity by this new approach.}, language = {en} } @misc{ZebingerGieratPasternaketal., author = {Zebinger, Markus and Gierat, Marek and Pasternak, Hartmut and Krausche, Thomas}, title = {Das Seilnetzdach der Schierker Feuerstein Arena im Harz Teil 2: Herstellung, Montage und Schweißsimulation}, series = {Bauingenieur}, volume = {93}, journal = {Bauingenieur}, number = {10}, issn = {0005-6650}, pages = {383 -- 391}, abstract = {Die Stadt Wernigerode in Sachsen-Anhalt errichtete im Ortsteil Schierke eine Multifunktionsarena. Am Fuße des Brockens, dem h{\"o}chsten Berg des Harzes und ganz Norddeutschlands gelegen, f{\"u}gt sich die offene {\"U}berdachung in die vorhandene Topologie nahtlos ein. Das unter Denkmalschutz stehende Natureisstadion, mit seinen bestehenden Natursteinterrassen und einem Schiedsrichterturm aus Holz, wurde baulich so konzipiert, dass die Arena in den Wintermonaten als {\"u}berdachte Kunsteisbahn und im Sommer als Fl{\"a}che f{\"u}r Konzerte, Auff{\"u}hrungen und Sportveranstaltungen genutzt werden kann. Eine ganz besondere Herausforderung war die Herstellung und Montage des circa 190m langen geschweißten Stahlrandtr{\"a}gers. Der Hohlkasten besteht aus vier doppelt gekr{\"u}mmten Blechen und lagert an lediglich zwei Fußpunkten auf. Der zweite Teil des Beitrags befasst sich mit Schweißeigenspannungen an einem ausgew{\"a}hlten Querschnitt der {\"U}berdachung.}, language = {de} } @misc{StapelfeldLaunertPasternaketal., author = {Stapelfeld, Christoph and Launert, Benjamin and Pasternak, Hartmut and Doynov, Nikolay and Michailov, Vesselin}, title = {Traglastberechnung versteifter Platten und Schalen unter Ber{\"u}cksichtigung realer Schweißimperfektionen}, series = {Bauingenieur}, volume = {93}, journal = {Bauingenieur}, number = {10}, issn = {0005-6650}, pages = {403 -- 411}, abstract = {Imperfektionen, die bei Traglastberechnungen Ber{\"u}cksichtigung finden m{\"u}ssen, haben ihre Ursachen in Herstellungs- und Fertigungstoleranzen oder werden durch das Schweißen und den damit zumeist einhergehenden Nachbehandlungen in den Bauteilen hervorgerufen. Durch die W{\"a}rmewirkung des Schweißens entstehen sowohl sehr große Verformungen als auch signifikante Zug und Druckspannungen. Der strukturelle und geometrische Imperfektionsgrad wird somit maßgeblich von der Anzahl und der Lage der Schweißn{\"a}hte sowie den Schweißparametern bestimmt. F{\"u}r die Ber{\"u}cksichtigung in Traglastberechnungen ist ein physikalisch fundiertes Modell erforderlich, welches die Schweißimperfektionen schnell und pr{\"a}zise berechnet. Das gekoppelte analytisch numerische Hybridmodell erf{\"u}llt diese Kriterien. Die mathematischen Grundlagen des analytischen Modells sowie die Kopplung mit der numerischen Finite-Elemente-Berechnung werden eingangs vorgestellt und die Anwendung zur Berechnung von Verz{\"u}gen an einer Schiffsektion demonstriert. Darauffolgend wird das Hybridmodell an einer eben und einer gekr{\"u}mmten versteiften Platte zur Berechnung der Schweißimperfektionen angewendet. Anschließende Traglastberechnungen sowie der Vergleich mit den Ergebnissen unter der Annahme einer geometrischen Ersatzimperfektion in Form des kritischsten Eigenwerts gibt Auskunft dar{\"u}ber, welches Potenzial die realit{\"a}tsnahe direkte Ber{\"u}cksichtigung von Schweißimperfektionen birgt.}, language = {de} } @inproceedings{LiPasternakPartov, author = {Li, Zheng and Pasternak, Hartmut and Partov, Doncho}, title = {Influence of statistical size effect in steel on structural safety}, series = {Proceedings of 16th International Conference on New Trends in Statics and Dynamics of Buildings}, booktitle = {Proceedings of 16th International Conference on New Trends in Statics and Dynamics of Buildings}, editor = {Jendželovsk{\´y}, Norbert and Grmanov{\´a}, Alžbeta}, publisher = {Slovak University of Technology}, address = {Bratislava}, isbn = {978-80-227-4845-2}, abstract = {This paper present the investigation of the statistical size effect in steel structure and the corresponding reliability. This study described the randomness of material properties through two different ways. These two proposed simulation methods, which are an extension and supplement to traditional simulation methods, can effectively simulate the statistical size effect for the tensile and flexural components in steel structures. The test results show that the variations of the yield and tensile strength increase with the decreasing specimen volume. Besides, the structural component strength is not only related to the specimen volume, but also the stress distribution. It is found by studying the influence of statistical size effect on structural reliability that the strength, which is obtained by small specimens through statistical analysis in the laboratory, is no more accurately applicable to large construction. The core idea is that the stochastic material proper-ties are directly embedded in mechanical calculations to develop a more accurate and economical design method for steel structure.}, language = {en} }