TY - CHAP A1 - Pasternak, Hartmut A1 - Krausche, Thomas T1 - Details of the steel assembly of a membrane-cladded double ­ curved cable net roof T2 - ICCAEE 2016 Kuala Lumpur/Malaysia, 2nd International Congress on Technology - Engineering & Science Y1 - 2016 PB - University of Malaysia CY - Pahang ER - TY - GEN A1 - Bartholomé, Susanne Elisabeth A1 - Pasternak, Hartmut A1 - Feldmann, Markus A1 - Geßler, Achim A1 - Ummenhofer, Thomas A1 - Ruff, Daniel T1 - Alternative Verstärkungsmaßnahme im Stahlbau mit aufgeklebten unidirektionalen CFK-Lamellen T2 - Schweißen und Schneiden Y1 - 2016 SN - 0036-7184 VL - 68 IS - 8 SP - 490 EP - 499 ER - TY - GEN A1 - Jäger, Andreas A1 - Pasternak, Hartmut T1 - Studien zum Beulverhalten von eng ringversteiften Kreiszylinderschalen unter Axialdruck T2 - Bauingenieur Y1 - 2016 SN - 0005-6650 VL - 91 IS - 10 SP - 401 EP - 409 ER - TY - GEN A1 - Bartholomé, Susanne Elisabeth A1 - Pasternak, Hartmut A1 - Feldmann, Markus A1 - Geßler, Achim A1 - Ummenhofer, Thomas A1 - Ruff, Daniel T1 - Geklebte CFK-Lamellen verstärken Stahlbauteile T2 - Adhäsion KW - Stahlbau KW - Verstärkung KW - CFK-Lamelle Y1 - 2016 UR - http://link.springer.com/article/10.1007/s35145-016-0039-6 SN - 1619-1919 SN - 2192-8681 VL - 60 IS - 9 SP - 42 EP - 49 ER - TY - GEN A1 - Bartholomé, Susanne Elisabeth A1 - Pasternak, Hartmut T1 - Träger mit schlanken, wabenförmig strukturierten Stegen - Versuch und Simulation T2 - Stahlbau Y1 - 2016 U6 - https://doi.org/10.1002/stab.201610423 SN - 1437-1049 SN - 0038-9145 VL - 85 IS - 11 SP - 724 EP - 732 ER - TY - CHAP A1 - Launert, Benjamin A1 - Rhode, Michael A1 - Kromm, Arne A1 - Pasternak, Hartmut A1 - Kannengießer, Thomas ED - Holden, Thomas M. ED - Muránsky, Ondrej ED - Edwards, Lyndon T1 - Residual Stress Influence on the Flexural Buckling of Welded I-Girders T2 - Residual Stresses 2016 – ICRS-10 N2 - The nonlinear analysis became a common tool to precisely assess the load-bearing behavior of steel beam and column members. The failure level is significantly influenced by different types of imperfections, among geometric also structural imperfections (residual stresses). Here are still gaps in the knowledge. Nowadays, 3-D welding simulation developed to a level where it could provide reliable estimation of weld-induced distortion and residual stresses. Nevertheless, modelling and computational effort are still in a less practicable range. In this study a simplified procedure to implement residual welding stresses in continuous large scale members is proposed and the influence on the ultimate limit state of slender members in compression is evaluated for two common structural steel grades. The results showed significant improvements in the utilization of load bearing capacity compared with simplified design methods. The comparatively general approach in this study offers potential for future optimization. KW - Stability Design KW - Finite Element Method KW - 2-D Welding Simulation KW - Inherent Strain KW - PDA Y1 - 2016 UR - http://www.mrforum.com/product/9781945291166/ SN - 978-1-94529116-6 U6 - https://doi.org/10.21741/9781945291173-19 SP - 109 EP - 114 PB - Materials Research Forum LLC CY - Millersville, PA ER - TY - CHAP A1 - Kromm, Arne A1 - Rhode, Michael A1 - Launert, Benjamin A1 - Dixneit, Jonny A1 - Kannengießer, Thomas A1 - Pasternak, Hartmut ED - Holden, Thomas M. ED - Muránsky, Ondrej ED - Edwards, Lyndon T1 - Combining Sectioning Method and X-Ray Diffraction for Evaluation of Residual Stresses in Welded High Strength Steel Components T2 - Residual Stresses 2016 - ICRS-10 N2 - Residual stresses and distortions in welded I-girders for steel construction are relevant when evaluating the stability of steel beams and column members. The application of high strength steels allows smaller wall thicknesses compared to conventional steels. Therefore, the risk of buckling has to be considered carefully. Due to the lack of knowledge concerning the residual stresses present after welding in high strength steel components conservative assumptions of their level and distribution is typically applied. In this study I-girders made of steels showing strengths of 355 MPa and 690 MPa were welded with varying heat input. Due to the dimension of the I-girders and the complex geometry the accessibility for residual stress measurement using X-ray diffraction was limited. Therefore, saw cutting accompanied by strain gauge measurement has been used to produce smaller sections appropriate to apply X-ray diffraction. The stress relaxation measured by strain gauges has been added to residual stresses determined by X-ray diffraction to obtain the original stress level and distribution before sectioning. The combination of both techniques can produce robust residual stress values. From practical point of view afford for strain gauge application can be limited to a number of measuring positions solely to record the global amount of stress relaxation. X-ray diffraction can be applied after sectioning to determine the residual stresses with sufficient spatial resolution. KW - Weld Residual Stress KW - Sectioning Method KW - X-Ray Diffraction Y1 - 2016 UR - http://www.mrforum.com/product/9781945291166/ SN - 978-1-94529116-6 U6 - https://doi.org/10.21741/9781945291173-28 SP - 163 EP - 168 PB - Materials Research Forum LLC CY - Millersville, PA ER - TY - GEN A1 - Launert, Benjamin A1 - Szczerba, Radosław A1 - Gajewski, Marcin A1 - Rhode, Michael A1 - Pasternak, Hartmut A1 - Giżejowski, Marian T1 - The buckling resistance of welded plate girders taking into account the influence of post-welding imperfections – Part 1: Parameter study T2 - Materials Testing N2 - Welding is the most important joining technique and offers the advantage of customizable plate thicknesses. On the other hand, welding causes residual stresses and deformations influencing the load carrying capacity. Their consideration in the design requires simple and fast models. Though welding simulation has contributed to accurately access to these values nowadays, their application to large components remains still in a less practicable range. Nevertheless, many studies emphasized the need to make corrections in recently available simplified models. Especially the influence of residual stresses seems somewhat overestimated in many cases if comparing conventional structural steel S355 and high-strength steel S690. In times of computer-aided design, an improved procedure to implement weld-inducted imperfections appears overdue. This will be presented in two parts. The first part illustrates the potential influence of post-welding imperfections exemplified for weak axis buckling in comparison with the general method in accordance with Eurocode 3. Residual stresses and initial crookedness were varied systematically in order to produce a scatter band of capacities. An approach to characterize the borders of these imperfections was undertaken before that. The excessive scattering of reduction factors for the load bearing capacity demonstrates the importance of these variables. Results were finally evaluated against advanced simulation models which will be further detailed in part two of this contribution. KW - Welded plate girders KW - stability KW - post-welding imperfections KW - residual stresses KW - parameter study Y1 - 2017 UR - http://www.hanser-elibrary.com/doi/abs/10.3139/120.110964 U6 - https://doi.org/10.3139/120.110964 SN - 0025-5300 VL - 59 IS - 1 SP - 47 EP - 56 ER - TY - GEN A1 - Launert, Benjamin A1 - Rhode, Michael A1 - Kromm, Arne A1 - Pasternak, Hartmut A1 - Kannengießer, Thomas T1 - Measurement and numerical modeling of residual stresses in welded HSLA component-like I-girders T2 - Welding in the World N2 - The present contribution shows the residual stress results obtained from experiments with the sectioning method in comparison to global (structural) welding simulation models on component-like (i.e., large scale) I-girders made of structural steel grades S355 and S690QL. Plates were welded by conventional gas metal arc welding using two different heat inputs. In addition, the base material was assumed to be approximately stress-free. Based on these results, conclusions and recommendations for the design of welded I-girders are drawn. KW - Residual Stresses KW - Microalloyed steels KW - Girders KW - MAG welding KW - Simulating Y1 - 2016 UR - http://rdcu.be/n6mU U6 - https://doi.org/10.1007/s40194-016-0413-x SN - 0043-2288 SN - 1878-6669 VL - 61 IS - 2 SP - 223 EP - 229 ER - TY - GEN A1 - Loebjinski, Maria A1 - Rug, Wolfgang A1 - Pasternak, Hartmut T1 - Zuverlässigkeitsbewertung von Holzbauteilen im Bestand T2 - Bauingenieur N2 - Die aktuellen Bemessungsnormen des Eurocodes beinhalten keine gesonderten Regelungen für bestehende Bauwerke. Dennoch sind diese aus verschiedenen Gründen spezifisch zu bemessen. Dazu gehören sowohl öko-nomische Gründe, als auch Anforderungen an die Erhaltung von historischen Konstruktionen. Dieser Beitrag fasst Grundlagen zur Zuverlässigkeitstheorie und zur Ermittlung von Teilsicherheitsbeiwerten zusammen, stellt den aktuellen Stand der Technik zu Normen und Standards der zuverlässigkeitstheoretischen Bemessung und zur Behandlung von Bestandsbauten in der Bemessung dar und zeigt mit vereinfachten Rechnungen das Opti-mierungspotential der Teilsicherheitsbeiwerte für historische Holzkonstruktionen auf. Y1 - 2017 SN - 0005-6650 VL - 92 IS - 2 SP - 65 EP - 73 ER - TY - CHAP A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut ED - Virdi, Kuldeep ED - Tenhunen, Lauri T1 - Bonding Technology in Steel Structures, a Summary of Research Activities at Chair of Steel and Timber Structures T2 - Proceedings of the METNET Seminar 2016 in Castellon Y1 - 2016 SN - 978-951-784-784-1 SP - 19 EP - 30 CY - Hämeenlinna ER - TY - GEN A1 - Pasternak, Hartmut A1 - Launert, Benjamin A1 - Kannengießer, Thomas A1 - Rhode, Michael T1 - Advanced Residual Stress Assessment of Plate Girders Through Welding Simulation T2 - Procedia Engineering N2 - This article provides an impression on potentials in applying nowadays welding simulation tools in construction design. This is carried out exemplary on plate girders from two structural steel grades. The calculated residual stresses are compared with measurements by sectioning method. It has been repeatedly stated that present Eurocode models fail to approximate the residual stresses. Especially for high strength steel (HSS) only limited information is available on realistic occurring residual stresses in typical I-girders. The investigations are aimed to give further guidance on these values. A few proposals on advanced models are discussed. KW - Residual stresses KW - Plate girders KW - I-shape sections KW - High-strength steel KW - Welding simulation KW - Advanced models Y1 - 2017 U6 - https://doi.org/10.1016/j.proeng.2017.02.013 SN - 1877-7058 VL - 172 SP - 23 EP - 30 ER - TY - GEN A1 - Kemper, Frank A1 - Ledecky, Lukas A1 - Feldmann, Markus A1 - Pasternak, Hartmut A1 - Fischer, Vitali T1 - Zeitabhängige Windbeanspruchungen von geklebten Fassadenanschlüssen T2 - Bauingenieur N2 - Für die Bemessung lastabtragender Klebverbindungen im Fassadenbereich ist zu beachten, dass die Windbelastungen auf den Bauwerksoberflächen sowohl zeitlich als auch räumlich veränderlich sind. Während für übliche Fassadenanschlüsse eine Bemessung mit charakteristischen Extremwerten ausreichend ist, muss beim Einsatz von sowohl höhermoduligen (z.B. Acrylat) als auch niedrigmoduligen (z.B. Polyurethan) Klebstoffen, die beide ein zeit- und temperaturabhängiges Materialverhalten aufweisen, eine vollständige Beschreibung dieser zeitbezogenen Lasteinwirkungen erfolgen. Nur dadurch wird letztlich die erforderliche betriebsfeste Auslegung eines geklebten Fassadenanschlusses ermöglicht. Im vorliegenden Beitrag wird die Ermittlung von zeitbezogenen Lasteinwirkungen und die Berechnung der daraus resultierenden Beanspruchungs-Zeit-Funktionen infolge einer natürlichen Windeinwirkungen auf Basis von Windkanalversuchen und Windstatistik thematisiert. Anhand geeigneter Zählverfahren und unter Berücksichtigung von klebstoffspezifischen Materialeigenschaften wird exemplarisch aufgezeigt, inwiefern unterschiedliche Fassadenpositionen und Windeigenschaften für die Auslegung von geklebten Fassadenanschlüssen von Bedeutung sind. Y1 - 2017 UR - http://www.bauingenieur.de/bauing/currentarticle.php?data[article_id]=87197 SN - 1436-4867 SN - 0005-6650 VL - 92 IS - 3 SP - 115 EP - 122 ER - TY - CHAP A1 - Simon, Flaviu A1 - Moradi, Milad A1 - Hildebrand, Jörg A1 - Pasternak, Hartmut ED - Hildebrand, Jörg ED - Loose, Tobias ED - Reich, Michael T1 - The influence of the welding sequence on the load bearing capacity and stress distribution of square hollow section steel joints T2 - Simulationsforum 2016, Schweißen und Wärmebehandlung, Weimar, Tagungsband 08.-10. November 2016 N2 - The aim of this contribution is to investigate the influence of welding sequencing patterns on the load bearing capacity of a S355 steel square hollow section (SHS) T-Joint. The failure and the joint behavior under loading condition are analyzed. The FE-software SYSWELD v2014 is used for the thermo-mechanical simulation of the welding process. The type of welding process used is metal active gas (MAG) welding. A fillet weld with a throat thickness of 5 mm is performed. After the welding simulation, the results in terms of stresses and distortion are validated with the experimental data. Due to the geometrical characteristics of this type of joint, a compressive test is performed. A load is applied on the upper surface the vertical member (brace). The force-displacement behavior is plotted and discussed. The differences and influencing parameters are identified. The model is prepared for the subsequent sensitivity study which will be done in the software OptiSLang, which is developed by Dynardo GmbH. Y1 - 2016 UR - http://www.fws-ev.de/fileadmin/downloads/Tagungsband_Simulationsforum_2016-Schweissen_und_Waermebehandlung_web.pdf SN - 978-3-00-054805-5 SP - 176 EP - 187 PB - Verein zur Förderung der numerischen Analyse der Wärmebehandlungs- und Schweißprozesse e.V. CY - Weimar ER - TY - CHAP A1 - Shlychkova, Darita A1 - Pasternak, Hartmut T1 - Numerical analysis of lightweight structured sandwich beams made of steel T2 - 16th International Scientific Conference VSU 2016, Sofia, 2016, vol. 1 N2 - Using a special technology it is possible to produce thin "honeycomb" structured plates. Such plates have been used e.g. for the roof of the sport complex "Olimp" in Odessa. That roof gives an extraordinary impression. That is why the question: how do structured plates behave as beams with C-section under concentrated force in the middle of the upper flange? In an ongoing project, two of those structured plates were assembled in different ways trough point welding. "Sandwich" beams were modelled and calculated using the nonlinear finite elements. Using Abaqus software load deformation curves for each beam and local stability were analyzed. Those sandwich beams may be used in exhibition stand construction. KW - Lightweight constructions, structured steel plates, sandwich beam, modelling Y1 - 2016 SP - 318 EP - 323 PB - VSU CY - Sofia ER - TY - CHAP A1 - Ledecky, Lukas A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut A1 - Fischer, Vitali A1 - Stammen, Elisabeth A1 - Dilger, Klaus T1 - Untersuchungen zum Tragverhalten und der Lebensdauer von Klebverbindungen im Stahlbau unter zyklischen Belastungen (LebKleb) T2 - 17. Kolloquium Gemeinsame Forschung in der Klebtechnik, Tagungsband, 14. - 15. Februar 2017 Y1 - 2017 SP - 37 EP - 38 PB - DECHEMA CY - Frankfurt am Main ER - TY - CHAP A1 - Ledecky, Lukas A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut A1 - Mette, Christoph A1 - Stammen, Elisabeth A1 - Dilger, Klaus T1 - Untersuchungen zum Tragverhalten und der Lebensdauer von Klebverbindungen im Stahlbau unter zyklischen Belastungen (LebKleb) T2 - 16. Kolloquium Gemeinsame Forschung in der Klebtechnik, Köln, 2016 Y1 - 2016 SP - 39 EP - 41 PB - DECHEMA CY - Frankfurt am Main ER - TY - GEN A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut A1 - Mette, Christoph A1 - Stammen, Elisabeth A1 - Dilger, Klaus T1 - Adhesive bonding in steel construction - Challenge and innovation T2 - Procedia Engineering Y1 - 2017 U6 - https://doi.org/10.1016/j.proeng.2017.02.048 SN - 1877-7058 N1 - Modern Building Materials, Structures and Techniques, MBMST 2016, Vilnius VL - 172 SP - 186 EP - 193 ER - TY - CHAP A1 - Li, Zheng A1 - Pasternak, Hartmut T1 - Development of a stochastic material model at constant stress distribution in steel construction T2 - 16th International Scientific Conference VSU 2016, Sofia, 2016, vol. 1 N2 - This paper briefly presents the results of theoretical and experimental investigations on the size effect in metal. The Chain of Bundle Model, which is based on a stochastic material model by Weibull and log-normal distribution, will be developed and the possibility to approximately determine the parameter ξ of the model is given. The tests were performed on specimens from the same steel with different sizes. According to the experiments, the relationship between the sizes of the specimens and the strength can be analyzed through probability- and reliability theory. The theoretical and experimental results show that if the volume increases hundredfold, the strength will be reduced to 90% ~ 95%. Therefore, the size effect plays an unnegligible role in steel construction. Y1 - 2016 SP - 193 EP - 198 PB - VSU CY - Sofia ER - TY - CHAP A1 - Pasternak, Hartmut A1 - Krausche, Thomas T1 - A special Construction Site: the Guyed Mast at Torfhaus in the Harz Mountains, Germany T2 - Risk and Safety Engineering, 12th International Conference, Kopaonik, 2017 Y1 - 2017 UR - http://www.rizik.vtsns.edu.rs/en/zbornici-radova/ SN - 978-86-6211-107-4 SP - 540 EP - 545 PB - The Higher Education Technical School of Professional Studies CY - Novi Sad ER - TY - GEN A1 - Linke, Gunter A1 - Rug, Wolfgang A1 - Pasternak, Hartmut T1 - Festigkeitssortierung von Bauholz in historischen Gebäuden - Bericht zum Stand der Technik T2 - Bauingenieur Y1 - 2017 VL - 92 IS - 5 SP - 229 EP - 236 ER - TY - GEN A1 - Stojković, Nenad A1 - Folić, Radomir A1 - Pasternak, Hartmut T1 - Mathematical model for the prediction of strength degradation of composites subjected to constant amplitude fatigue T2 - International Journal of Fatigue Y1 - 2017 U6 - https://doi.org/10.1016/j.ijfatigue.2017.06.032 SN - 0142-1123 VL - 103 SP - 478 EP - 487 ER - TY - RPRT A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Rhode, Michael A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Erhöhung der Tragfähigkeit geschweißter I-Träger aus hochfestem Baustahl durch verbesserte Ansätze zur Berücksichtigung von Eigenspannungen Y1 - 2017 UR - https://www-docs.b-tu.de/fg-stahlbau/public/Fachgebiet_Stahlbau/AiF_TragEig/Kurvorstellung_P1035.pdf ER - TY - GEN A1 - Launert, Benjamin A1 - Pasternak, Hartmut T1 - Weld residual stresses effects in the design of welded plate girders: Simulation and Implementation T2 - Ce/papers N2 - Eurocode 3 offers different possibilities on a numerically-aided design of welded plate girders. In this, a geometrically and materially nonlinear analysis of the imperfect structure (GMNIA) provides the theoretically highest possible degree of realism. A correct implementation of “imperfections” is of critical importance in the practical application of this method. The current design rules are based on long term experience in terms of traditional (“old”) welding procedures and regular (“low strength”) steel grades. Thus, they provide very approximate (but safe) rules for these structures. With the introduction of modern shop welding operations and materials, many of these assumptions seem to be over-conservative. A revision of these rules is being processed in different national and international research projects. This particular study focusses on the weld residual stresses and their effects in conventional steel S355 and high strength steel S690. Metal active gas (MAG) welding under shop welding conditions was used. The measurement of weld residual stresses on component-like samples (carried out by the BAM Bundesanstalt für Materialforschung und -prüfung in Berlin) has been widely published. The hereupon based (simplified) welding simulation as part of a subsequent structural analysis is shown here. A novel numerical approach how to directly incorporate the results into large structural components models is presented. The capacity analysis is performed on a simple example for weak-axis buckling. The results indicate significant improvements in the utilization of load-bearing capacity and underline the superior buckling assignment for the S690 compared to conventional S355. The experimental validation of the findings is currently being prepared. KW - Stability KW - Welding imperfections KW - Residual stresses KW - Welding simulation KW - Nonlinear analysis Y1 - 2017 UR - http://onlinelibrary.wiley.com/doi/10.1002/cepa.144/abstract U6 - https://doi.org/10.1002/cepa.144 SN - 2509-7075 VL - 1 IS - 2-3 SP - 1039 EP - 1047 ER - TY - GEN A1 - Krausche, Thomas A1 - Launert, Benjamin A1 - Pasternak, Hartmut T1 - A study on the prediction of welding effects in steel box girders T2 - Ce/papers N2 - For standard sections including I-girders and rectangular box girders, several approaches on geometrical and structural imperfections are given in the literature, which can be implemented in a numerical analysis. For complex sections, as found in many of today's lightweight roof structures, these assumptions are conservative due to the sections typically unique shape, which leads to increased thicknesses or additional stiffening of the plates. This, on the other hand, can significantly affect fabrication costs. This paper aims to provide an overview on the possibilities in the numerical prediction of weld residual stresses and weld-induced deformations for these sections. The obtained values can be used in a subsequent numerical analysis to understand the structural behavior and optimize the design. A representative example on a section used in a steel compression ring is described and analyzed using the numerical welding simulation. A simplification of the originally transient weld procedure is used in order to reduce computation times to a practically reasonable level. In this context, the Abaqus Welding Interface (AWI) helps to automate working steps in conjunction with the definition of weld passes and their sequencing, which shall be shown in here. The applicability of this method is discussed showing also a need of further investigations in this field. This is especially with regard to result quality, which requires some experimental back-up. Nonetheless, this method could already help to show up tendencies or to identify potential critical spots in the design. KW - Innovative structures KW - Welding simulation KW - Abaqus Welding Interface Y1 - 2017 UR - http://onlinelibrary.wiley.com/doi/10.1002/cepa.500/abstract U6 - https://doi.org/10.1002/cepa.500 SN - 2509-7075 VL - 1 IS - 2-3 SP - 4410 EP - 4416 ER - TY - GEN A1 - Ciupack, Yvonne A1 - Ledecký, Lukáš A1 - Pasternak, Hartmut A1 - Fischer, Vitali A1 - Stammen, Elisabeth A1 - Dilger, Klaus T1 - Bonded steel joints under cyclic loading: Study on structural behaviour and fatigue T2 - ce/papers Y1 - 2017 U6 - https://doi.org/10.1002/cepa.87 SN - 2509-7075 VL - 1 IS - 2/3 SP - 505 EP - 513 ER - TY - CHAP A1 - Li, Zheng A1 - Pasternak, Hartmut ED - Bucher, Christian ED - Ellingwood, Bruce R. ED - Frangopol, Dan M. T1 - Reliability analysis of size effect on flexural members with stochastic finite element method T2 - 12th International Conference on Structural Safety & Reliability, Vienna, Austria, 6–10 August 2017 Y1 - 2017 SN - 978-3-903024-28-1 PB - TU-MV Media Verlag CY - Vienna ER - TY - CHAP A1 - Loebjinski, Maria A1 - Rug, Wolfgang A1 - Pasternak, Hartmut ED - Bucher, Christian ED - Ellingwood, Bruce R. ED - Frangopol, Dan M. T1 - Approaches for an optimisation of partial safety factors for historic timber structures T2 - Safety, Reliability, Risk, Resilience and Sustainability of Structures and Infrastructure, 12th International Conference on Structural Safety & Reliability, Vienna, Austria, 6–10 August 2017 Y1 - 2017 SN - 978-3-903024-28-1 PB - TU-MV Media Verlag CY - Vienna ER - TY - CHAP A1 - Pasternak, Hartmut A1 - Krausche, Thomas T1 - Design, constructions and assembly of two membrane-cladded double-curved cable net roofs T2 - 6th Structural Engineers World Congress (SEWC 2017), Cancun/Mexico N2 - For stadium roofs light weight constructions, that are tensioned between a cantilevering steel compression ring, are commonly build around the globe, mostly for social events like sport games and concerts. They allow having no columns in the viewing area and also spanning the whole arena. With the additional use of membranes as the roof shell, the inside of the building will get naturally lighted. With the knowledge of the occurring loads, an economic structure can be found to optimize the edge structure. Frequently the form finding process will use the death loads as decisive action because for only one load case a moment free form can be determined. Other load cases will cause bending in the girder. The process also allows having only supports at the low points and a cantilever arises. These types of roofs will be compared with two exemplary canopies in Germany. The main focus will be on the assembly of the edge girder, which will evoke challenges for planning as well as the actual manufacturing process. The steel edge girder is double curved and has a spatially shape. The welded box exists of 4 to 5 curving plates that have thicknesses from 15mm to 55mm and will vary in their height. Due to welding residual stresses occur during the assembly in the factory as well as on the construction side. For the design of the girders, the residual stresses need to be determined. The identified results of the residual stresses will vary through the plate thickness and will differ for residual longitudinal and residual transverse stresses. The longitudinal residual stresses, as the relevant residual stresses for axial forces, will be farther scrutinized. Due to its complex geometry the challenges of the simulation will be presented for the manufacturing process and the construction site assembly. For the farther investigation the calculated stresses will be taken for a load capacity calculation of a section of the edge girder. Due to the forming geometry and the welding process, both effects need to be considered. This calculation will also show that the edge girder needs to be stiffened in the inside with bulkhead plate’s und longitudinal stiffeners. Both authors are involved in the verification of the objects (Customer Centre in the Autostadt Wolfsburg-CC, Schierke-Arena ‐FA in the Harz Mountains) mentioned below. Y1 - 2017 UR - http://sewc2017.org/ PB - Universidad Nacional Autónoma de México - UNAM ER - TY - CHAP A1 - Krausche, Thomas A1 - Launert, Benjamin A1 - Pasternak, Hartmut T1 - Welding effects in unregularly steel box girders T2 - 6th Structural Engineers World Congress (SEWC 2017), Cancun/Mexico N2 - Several approaches on geometrical and structural imperfections are given in the literature for I sections and rectangular box girders. Those approximations of the residuals stress state can be implemented into the structural analysis using multi-purpose FEM program packages. The knowledge of the stress state of free forming cross sections has still to be determined. To fulfil a safe design, the assumptions mostly will be very conservative due to the lack of the assumed stress state. This will result directly to increased thicknesses or additional stiffening of the plates. Not only the material cost will rise, but also the fabrication costs like welding will be affected. This paper aims to provide an overview on the possibilities in the numerical prediction of weld residual stresses and weld induced deformations for cross sections with unique shapes. With the obtained values the tendencies of the residual stress state and deformations will be used to optimize the design. A representative example on a section used in a steel compression ring of a realized roof is described and analyzed using a simplification of a numerical welding simulation. The reduced simulation of the originally transient weld procedure was held to a practically reasonable level and can be reproduced for similar problems. The calculations used the Abaqus Welding Interface (AWI) to automate working steps in conjunction with the definition of weld passes and their sequencing. The field of the method that is discussed also a need of further investigations to prove its applicability. Some experimental back up is requires to verify the result quality. Nonetheless, this method could already help to show up tendencies or to identify potential critical spots in the design. Y1 - 2017 UR - http://sewc2017.org/ PB - Universidad Nacional Autónoma de México - UNAM ER - TY - CHAP A1 - Pasternak, Hartmut A1 - Jäger-Cañás, Andreas T1 - On the axial buckling of very thin-walled cylindrical shells T2 - Ce/papers : the online collection for conference papers in civil engineering N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1002/cepa.127 SN - 2509-7075 VL - 1 IS - 2-3 SP - 868 EP - 877 ER - TY - CHAP A1 - Jäger-Cañás, Andreas A1 - Pasternak, Hartmut T1 - Influence of closely spaced ring-stiffeners on the axial buckling behavior of cylindrical shells T2 - Ce/papers : the online collection for conference papers in civil engineering N2 - 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. Y1 - 2017 U6 - https://doi.org/10.1002/cepa.133 SN - 2509-7075 VL - 1 IS - 2-3 SP - 928 EP - 937 ER - TY - CHAP A1 - Pasternak, Hartmut A1 - Zivaljevic-Luxor, Natasa T1 - Evolution of an heritage edifice from colossus in Prora to colossus of Prora T2 - 3rd International Conference on Protection of Historical Constructions Y1 - 2017 SN - 978-989-8481-58-0 N1 - +CD SP - 387 EP - 388 PB - IST Press CY - Lisbon ER - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Numerische Festigkeitsberechnung einer versteiften Struktur unter Berücksichtigung realitätsnaher geometrischer und struktureller Imperfektionen T2 - 110 Jahre DASt und 21. DASt-Forschungskolloquium an der Technischen Universität Kaiserslautern, 6./7. März 2018 N2 - Die Festigkeitsberechnung von Strukturen, zum Beispiel Platten oder Schalen, mittels der Finite-Elemente-Methode gehört schon seit längerem zum Stand der Technik. Berücksichtigt werden bei der Berechnung sowohl geometrische Nichtlinearitäten 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 gemäß DIN EN 1993-1-5 erhöht. In einem Kommentar zur selben Norm findet sich ebenfalls eine Empfehlung zur Berücksichtigung von Schweißimperfektionen in Form von vereinfachten Längseigenspannungsverläufen. Diese werden in Abhängigkeit der Fließgrenzspannung des Werkstoffs bei Raumtemperatur und der Dicken der Fügepartner angenommen. Sowohl die Annahme rein geometrischer Imperfektionen als auch die Berücksichtigung vereinfachter Eigenspannungszustände, sind mit Sicherheitszuschlägen behaftet. Durch eine realitätsnähere Berücksichtigung von strukturellen und geometrischen Imperfektionen, hervorgerufen durch Schweißprozesse, kann die tatsächliche Tragfähigkeit 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 Zusammenhänge eingegangen. Es folgt die Erläuterung des Kopplungsalgorithmus zwischen analytischem Modell und der numerischen Berechnung. Angewendet an der doppelt versteiften Platte, wird ein realitätsnaher geometrischer und struktureller Imperfektionszustand berechnet. Eine anschließende Traglastanalyse gibt Aufschluss über 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 Längsrichtung invers, durch den Vergleich der ersten 6 Beulformen sowie der Last-Verformungskurven dreier Imperfektionen, bestimmt. Darauf aufbauen wird die Last-Verformungskurve für einen überlagerten Imperfektionszustand berechnet, wobei die geometrischen Imperfektionen aus den Fertigungstoleranzen abgeleitet und die strukturellen idealisiert, gemäß DIN EN 1993-1-5, gewählt werden. Abschließend werden alle Last-Verformungskurven einander gegenübergestellt. Anhand des Vergleichs kann quantifiziert werden, wie konservativ die einzelnen angenommenen Imperfektionen sind und wie sich der Verformungsverlauf darstellt, berechnet man diesen unter Verwendung realitätsnaher geometrischer und struktureller Imperfektionen. Y1 - 2018 SN - 978-3-941687-27-1 SP - 245 EP - 249 PB - Deutscher Ausschuß für Stahlbau DASt CY - Düsseldorf ER - TY - CHAP A1 - Jäger-Cañás, Andreas A1 - Pasternak, Hartmut T1 - Zum Tragverhalten ringversteifter Schalen unter Axialdruck T2 - 110 Jahre DASt und 21. DASt-Forschungskolloquium an der Technischen Universität Kaiserslautern, 6./7. März 2018 N2 - Ringsteifen werden typischerweise bei dünnwandigen Tanks am Mantel befestigt, um auch für starken Wind und/oder Unterdruck eine ausreichende Beulsicherheit sicherzustellen. Eine Vielzahl an Veröffentlichungen zum Thema Ringsteifen beschäftigt sich ausschließlich mit den vorher genannten Lastfällen. Dagegen ist der traglaststeigernde Einfluss der Ringsteifen im Lastfall Axialdruck kaum erforscht. Experimentell wurde vor allem in den 1960er und 1970er Jahren gegenüber unversteiften Schalen, für eng-ringversteifte ein erheblich verbessertes Tragverhalten nachgewiesen. Der eingeschränkte Parameterbereich der Untersuchungen verhindert jedoch die Anwendung der Erkenntnisse im Metallbau, wo, aufgrund der Fertigungskosten, eher wenige, dafür kräftigere 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 Steifenabständen bis zum Zehnfachen der klassischen Beulhalbwellenlänge 1.73√rt. Es wird gezeigt, dass auch mit versteiften Schalen, bei denen der Steifenabstand größer als zwei Beulhalbwellenlängen ist, noch Tragfähigkeitssteigerungen gegenüber der unversteiften Schale erreicht werden können. Erwartungsgemäß sind die Zugewinne an Traglast bei enger versteiften Kreiszylindern am größten, wobei vor allem dünnwandige Strukturen von der verringerten Imperfektionssensitivität 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 überdachten Silos und windbelasteten Flachbodentanks der Fall. Dafür ist kein zusätzlicher Konstruktionsaufwand notwendig, da lediglich die ohnehin vorhandene Struktur vorteilhafter ausgenutzt wird. Y1 - 2018 SN - 978-3-941687-27-1 SP - 227 EP - 232 PB - Deutscher Ausschuß für Stahlbau DASt CY - Düsseldorf ER - TY - CHAP A1 - Ledecky, Lukas A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut A1 - Geßler, Achim A1 - Feldmann, Markus ED - Virdi, Kuldeep ED - Tenhunen, Lauri T1 - Reduction of Fatigue Crack Growth Rate in Compact Tension Specimens Using Adhesively Bonded CFRP-Strips T2 - Proceedings of the METNET Seminar 2017 in Cottbus Y1 - 2018 UR - https://issuu.com/hamkuas/docs/hamk_metnet_cottbus_2017 SN - 978-951-784-794-0 SP - 30 EP - 42 PB - Häme University of Applied Sciences (HAMK) CY - Hämeenlinna ER - TY - CHAP A1 - Ciupack, Yvonne A1 - Pasternak, Hartmut A1 - Yilmaz, Emre Mehmet A1 - Sternsdorff, Florian A1 - Vayas, Ioannis ED - Virdi, Kuldeep ED - Tenhunen, Lauri T1 - Hybrid Reinforcement Measures and Innovative Measurement Methods in Steel Construction T2 - Proceedings of the METNET Seminar 2017 in Cottbus Y1 - 2018 UR - https://issuu.com/hamkuas/docs/hamk_metnet_cottbus_2017 SN - 978-951-784-794-0 SP - 43 EP - 55 PB - Häme University of Applied Sciences (HAMK) CY - Hämeenlinna ER - TY - CHAP A1 - Pasternak, Hartmut A1 - Ciupack, Yvonne A1 - Ledecky, Lukas A1 - Dilger, Klaus A1 - Stammen, Elisabeth A1 - Fischer, Vitali T1 - Untersuchungen zum Tragverhalten und der Lebensdauer von Klebverbindungen im Stahlbau unter zyklischer Belastung T2 - 18. Kolloquium Gemeinsame Forschung in der Klebtechnik, Köln, 27. - 28. Februar 2018 Y1 - 2018 SP - 62 EP - 64 PB - DECHEMA CY - Frankfurt am Main ER - TY - GEN A1 - Garifullin, Marsel A1 - Launert, Benjamin A1 - Heinisuo, Markku A1 - Pasternak, Hartmut A1 - Mela, Kristo A1 - Pajunen, Sami T1 - Effect of welding residual stresses on local behavior of rectangular hollow section joints. Part 1 - Development of numerical model T1 - Einfluss der Schweißeigenspannungen auf die Tragfähigkeit von Rechteck-Hohlprofil-Knoten. Teil 1: Entwicklung eines numerischen Modells) T2 - Bauingenieur N2 - 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. N2 - Geschweißte Hohlprofilknoten sind aufgrund besserer Festigkeits – und Steifigkeitseigenschaften im Vergleich zu offenen Profilen sowie ihrer einfacheren Fertigung weit verbreitet. Schweißeigenspannungen, die infolge des Fügens der Einzelkomponenten mittels Schweißen entstehen, können deren Tragverhalten zum Teil stark beeinflussen, was auch durch einige neuere Untersuchungen belegt wird. Dieser Beitrag beschreibt eine erweiterte Vorgehensweise für die Finite-Elemente-Modellierung am Beispiel eines T-Knotens aus Rechteckhohlprofilen. Der Beitrag gliedert sich in zwei Teile. Teil 1 beinhaltet die Entwicklung und Validierung eines numerischen Modells, welches Schweißeinflüsse durch eine vorangehende thermomechanische Simulation explizit modelliert und diese in nachfolgende Berechnungsschritte einbezieht. Dabei werden die Bedeutung einer geeigneten Vernetzung des Modells, der Materialeigenschaften und eines zutreffenden Schweißwärmeeintrags diskutiert. Die Validierung mit experimentellen Ergebnissen zeigt die Eignung des entwickelten numerischen Modells und dass dieses das lokale Tragverhalten entsprechender Knotenverbindungen korrekt erfasst. Es kann daher für nachfolgende Untersuchungen weiterverwendet werden. Teil 2 zeigt die diesbezüglich durchgeführten Parameterstudien, um die Auswirkungen der Schweißeigenspannungen auf die Tragfähigkeit und die Anfangssteifigkeit der untersuchten Knotenverbindung darzustellen. KW - Einfluss der Eigenspannungen auf Verbindungen Y1 - 2018 UR - https://www.bauingenieur.de/bauing/article.php?data[article_id]=89266 SN - 1436-4867 SN - 0005-6650 VL - 93 IS - 4 SP - 152 EP - 159 ER - TY - GEN A1 - Partov, Doncho A1 - Pasternak, Hartmut A1 - Petkov, Milen A1 - Nikolov, Radoslav A1 - Dimitrova, Antoaneta T1 - About the history of orthotropic bridge decks T2 - Annual of the University of Architecture, Civil Engineering and Geodesy, Sofia N2 - 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. Y1 - 2018 SN - 1310-814X VL - 51 IS - 4 SP - 295 EP - 311 ER - TY - GEN A1 - Garifullin, Marsel A1 - Launert, Benjamin A1 - Heinisuo, Markku A1 - Pasternak, Hartmut A1 - Mela, Kristo A1 - Pajunen, Sami T1 - Effect of welding residual stresses on local behavior of rectangular hollow section joints. Part 2 – Parametric studies T1 - Einfluss der Schweißeigenspannungen auf die Tragfähigkeit von Rechteck-Hohlprofil-Knoten. Teil 2 – Parameterstudien T2 - Bauingenieur N2 - 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. N2 - Schweißeigenspannungen können das Tragverhalten geschweißter Hohlprofilknoten zum Teil stark beeinflussen. Um mögliche negative Einflüsse auf die Tragfähigkeit auszuschließen, sollte der Eigenspannungseinfluss mitberücksichtigt werden. Dieser Beitrag bildet den zweiten Teil einer numerischen Untersuchung an geschweißten Rechteck-Hohlprofil-Knoten unter Berücksichtigung der vorgenannten Spannungen. Darin werden in Teil 1 entwickelten Modelle dazu verwendet, deren Auswirkungen auf die Tragfähigkeit und die Anfangssteifigkeit der Knotenverbindung darzustellen. Die Ergebnisse zeigen im untersuchten Parameterfeld eine Traglaststeigerung zwischen 1 % und 19 %. Die Anfangssteifigkeit wird generell nur geringfügig reduziert. Gleichzeitig wird gezeigt, dass die Schweißreihenfolge in den untersuchten Fällen keinen nennenswerten Einfluss auf die Tragfähigkeit ausübt. Y1 - 2018 UR - https://www.bauingenieur.de/bauing/article.php?data[article_id]=89481 SN - 1436-4867 SN - 0005-6650 VL - 93 IS - 5 SP - 207 EP - 213 ER - TY - GEN A1 - Li, Zheng A1 - Launert, Benjamin A1 - Pasternak, Hartmut T1 - Application of the stochastic finite element method in welding simulation T2 - Welding in the World N2 - 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. Y1 - 2018 UR - https://rdcu.be/NT9F U6 - https://doi.org/10.1007/s40194-018-0596-4 SN - 0043-2288 SN - 1878-6669 VL - 62 IS - 5 SP - 905 EP - 912 ER - TY - CHAP A1 - Garifullin, Marsel A1 - Launert, Benjamin A1 - Heinisuo, Markku A1 - Pasternak, Hartmut A1 - Mela, Kristo A1 - Pajunen, Sami T1 - Effect of Welding Residual Stresses on Behavior of Tubular T Joints T2 - 17th International Conference on Computing in Civil and Building Engineering N2 - 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. Y1 - 2018 UR - http://programme.exordo.com/icccbe2018/delegates/presentation/267/ UR - https://icccbe2018.exordo.com/files/papers/104/final_draft/Effect_of_Welding_Residual_Stresses_on_Behavior_of_Tubular_T_Joints.pdf ER - TY - CHAP A1 - Zivaljevic-Luxor, Natasa A1 - Pasternak, Hartmut T1 - Roofs for archaeological sites integration into public space of metropolitan area T2 - International Scientific Conference, Nis, Serbia, 31.08-01-09.2018 Y1 - 2018 UR - https://www.b-tu.de/fg-stahlbau/publikationen/veroeffentlichungen ER - TY - CHAP A1 - Jäger-Cañás, Andreas A1 - Pasternak, Hartmut T1 - On the buckling behavior of ring-stiffened shells under axial compression T2 - 8th International Conference on Thin-Walled Structures, ICTWS 2018, Lisbon, Portugal, July 24-27, 2018 Y1 - 2018 UR - https://www.b-tu.de/fg-stahlbau/publikationen/veroeffentlichungen ER - TY - CHAP A1 - Loebjinski, Maria A1 - Rug, Wolfgang A1 - Pasternak, Hartmut ED - Rug, Wolfgang T1 - Aktuelle Normen für den Bestandsbau mit Holz und beispielhafte Zuverlässigkeitsuntersuchungen T2 - Holzbau im Bestand - historische Holztragwerke : Beispiele für substanzschonende Erhaltung Y1 - 2018 SN - 978-3-410-28175-7 SP - 162 EP - 192 PB - Beuth Verlag CY - Berlin ER - TY - CHAP A1 - Loebjinski, Maria A1 - Rug, Wolfgang A1 - Pasternak, Hartmut T1 - Possibilities for a modification of partial safety factors for existing timber structures T2 - World Conference on Timber Engineering, Seoul, 20 - 23 Aug 2018 Y1 - 2018 UR - https://indico.conference4me.psnc.pl/event/171/session/347/contribution/136/material/paper/1.pdf ER - TY - CHAP A1 - Partov, Doncho A1 - Pasternak, Hartmut A1 - Grekov, Petar A1 - Nikolov, Radoslav A1 - Dimitrova, Antoaneta T1 - 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 T2 - X Jubilee International Scientific Conference „Civil Engineering Design and Construction“, Sept. 20-22, 2018, Varna, Bulgaria Y1 - 2018 UR - https://www.b-tu.de/fg-stahlbau/publikationen/veroeffentlichungen SP - 469 EP - 481 ER - TY - CHAP A1 - Loebjinski, Maria A1 - Köhler, Jochen A1 - Rug, Wolfgang A1 - Pasternak, Hartmut ED - Caspeele, Robby ED - Taerwe, Luc ED - Frangopol, Dan M. T1 - Development of an optimization-based and practice orientated assessment scheme for the evaluation of existing timber structures T2 - Life-Cycle Analysis and Assessment in Civil Engineering: Towards an Integrated Vision Y1 - 2019 SN - 978-1-138-62633-1 SN - 978-1-315-22891-4 SP - 353 EP - 360 PB - Taylor & Francis Group CY - London ER - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin ED - Seefeldt, Marc T1 - Strength Calculation of Stiffened Structures Taking Into Consideration Realistic Weld Imperfections T2 - European Conference on Residual Stresses 2018, ECRS-10, Leuven, Belgium, 11-14th September, 2018 N2 - 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. Y1 - 2018 SN - 978-1-945291-88-3 SN - 978-1-945291-89-0 U6 - https://doi.org/10.21741/9781945291890-39 SP - 245 EP - 250 PB - Materials Research Forum LLC CY - Millersville, PA ER - TY - GEN A1 - Zebinger, Markus A1 - Gierat, Marek A1 - Pasternak, Hartmut A1 - Krausche, Thomas T1 - Das Seilnetzdach der Schierker Feuerstein Arena im Harz Teil 2: Herstellung, Montage und Schweißsimulation T2 - Bauingenieur N2 - Die Stadt Wernigerode in Sachsen-Anhalt errichtete im Ortsteil Schierke eine Multifunktionsarena. Am Fuße des Brockens, dem höchsten Berg des Harzes und ganz Norddeutschlands gelegen, fügt sich die offene Überdachung 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 überdachte Kunsteisbahn und im Sommer als Fläche für Konzerte, Aufführungen und Sportveranstaltungen genutzt werden kann. Eine ganz besondere Herausforderung war die Herstellung und Montage des circa 190m langen geschweißten Stahlrandträgers. Der Hohlkasten besteht aus vier doppelt gekrümmten Blechen und lagert an lediglich zwei Fußpunkten auf. Der zweite Teil des Beitrags befasst sich mit Schweißeigenspannungen an einem ausgewählten Querschnitt der Überdachung. Y1 - 2018 SN - 0005-6650 VL - 93 IS - 10 SP - 383 EP - 391 ER - TY - GEN A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Traglastberechnung versteifter Platten und Schalen unter Berücksichtigung realer Schweißimperfektionen T2 - Bauingenieur N2 - Imperfektionen, die bei Traglastberechnungen Berücksichtigung finden müssen, haben ihre Ursachen in Herstellungs- und Fertigungstoleranzen oder werden durch das Schweißen und den damit zumeist einhergehenden Nachbehandlungen in den Bauteilen hervorgerufen. Durch die Wärmewirkung 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 Schweißnähte sowie den Schweißparametern bestimmt. Für die Berücksichtigung in Traglastberechnungen ist ein physikalisch fundiertes Modell erforderlich, welches die Schweißimperfektionen schnell und präzise berechnet. Das gekoppelte analytisch numerische Hybridmodell erfüllt 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 Verzügen an einer Schiffsektion demonstriert. Darauffolgend wird das Hybridmodell an einer eben und einer gekrümmten 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 darüber, welches Potenzial die realitätsnahe direkte Berücksichtigung von Schweißimperfektionen birgt. Y1 - 2018 SN - 0005-6650 VL - 93 IS - 10 SP - 403 EP - 411 ER -