@inproceedings{PasternakKrauscheLaunert, author = {Pasternak, Hartmut and Krausche, Thomas and Launert, Benjamin}, title = {Welding of Thick Plates under Site Conditions - Evaluation of the Influence on the Structure Behaviour of Welded Assembly Joints}, series = {Design, fabrication and economy of metal structures, international conference proceedings 2013, Miskolc, Hungary, April 24 - 26, 2013}, booktitle = {Design, fabrication and economy of metal structures, international conference proceedings 2013, Miskolc, Hungary, April 24 - 26, 2013}, publisher = {Springer}, address = {Heidelberg}, isbn = {978-3-642-36690-1}, pages = {455 -- 460}, language = {en} } @misc{SchwitzkeBachmannNoacketal., author = {Schwitzke, Marko and Bachmann, Volkmar and Noack, Matthias and Freyer, Thomas and Launert, Benjamin}, title = {Methodische Ans{\"a}tze zum Rissmonitoring an Bauteilen durch automatisierte digitale Analyse}, series = {Bauingenieur}, volume = {85}, journal = {Bauingenieur}, number = {11}, issn = {0005-6650}, pages = {455 -- 459}, language = {de} } @inproceedings{BachmannKrauscheLaunertetal., author = {Bachmann, Volkmar and Krausche, Thomas and Launert, Benjamin and Klassen, Jakob}, title = {Schweißen dicker Bleche unter Baustellenbedingungen}, series = {18. DASt-Kolloquium, Aachen, 2012}, booktitle = {18. DASt-Kolloquium, Aachen, 2012}, publisher = {Frehner Consulting}, address = {F{\"u}ssen}, isbn = {978-3-929371-26-0}, pages = {113 -- 118}, language = {de} } @misc{PasternakKrauscheLaunert, author = {Pasternak, Hartmut and Krausche, Thomas and Launert, Benjamin}, title = {Schweißen von Tr{\"a}gern mit dicken Blechen, Teil 2: Schweißen unter Baustellenbedingungen - Montagestoß und Variation der Umgebungstemperatur}, series = {Bauingenieur}, volume = {89}, journal = {Bauingenieur}, number = {12}, issn = {0005-6650}, pages = {537 -- 547}, language = {de} } @inproceedings{PasternakLaunert, author = {Pasternak, Hartmut and Launert, Benjamin}, title = {Improved design approaches for the load bearing capacity of welded I-profiles from high strength steel considering realistic residual stresses}, series = {7th European Conference on Steel and Composite Structures (Eurosteel), Napoli, 2014}, booktitle = {7th European Conference on Steel and Composite Structures (Eurosteel), Napoli, 2014}, publisher = {ECCS European Convention for Constructional Steelwork}, address = {Brussels}, isbn = {978-92-9147-121-8}, pages = {159 -- 160}, language = {en} } @inproceedings{PasternakLaunert, author = {Pasternak, Hartmut and Launert, Benjamin}, title = {Erh{\"o}hung der Tragf{\"a}higkeit geschweißter I-Profile aus hochfestem Baustahl - Verbesserte Ans{\"a}tze zur Eigenspannungserfassung}, series = {19. DASt-Forschungskolloquium, 27.-28.Oktober 2014, Hannover}, booktitle = {19. DASt-Forschungskolloquium, 27.-28.Oktober 2014, Hannover}, publisher = {DASt}, address = {D{\"u}sseldorf}, isbn = {978-3-929371-33-8}, language = {de} } @misc{PasternakKrauscheLaunert, author = {Pasternak, Hartmut and Krausche, Thomas and Launert, Benjamin}, title = {Schweißen von Tr{\"a}gern mit dicken Blechen, Teil 1: Tr{\"a}gerfertigung unter Werksbedingungen - Planung, Herstellung und Simulation}, series = {Bauingenieur}, volume = {89}, journal = {Bauingenieur}, number = {10}, issn = {1436-4867}, pages = {395 -- 404}, language = {de} } @inproceedings{PasternakKrauscheLaunert, author = {Pasternak, Hartmut and Krausche, Thomas and Launert, Benjamin}, title = {Welding of thick steel plates under site conditions}, series = {7th European Conference on Steel and Composite Structures, Eurosteel, Neapel, 2014}, booktitle = {7th European Conference on Steel and Composite Structures, Eurosteel, Neapel, 2014}, publisher = {ECCS European Convention for Constructional Steelwork}, address = {Brussels}, isbn = {978-92-9147-121-8}, pages = {109 -- 110}, language = {en} } @inproceedings{KrauscheLaunert, author = {Krausche, Thomas and Launert, Benjamin}, title = {Schweißen dicker Bleche unter Baustellenbedingungen}, series = {BTU Stahlbau-Symposium 2014, Cottbus, 2014}, booktitle = {BTU Stahlbau-Symposium 2014, Cottbus, 2014}, publisher = {BTU}, address = {Cottbus [u.a.]}, pages = {17 -- 24}, language = {de} } @inproceedings{MoradiLaunert, author = {Moradi, Milad and Launert, Benjamin}, title = {Welding induced stresses and deformation in tubes}, series = {BTU Stahlbau-Symposium 2014}, booktitle = {BTU Stahlbau-Symposium 2014}, publisher = {BTU}, address = {Cottbus [u.a.]}, pages = {91 -- 98}, language = {en} } @misc{PasternakLaunertKrausche, author = {Pasternak, Hartmut and Launert, Benjamin and Krausche, Thomas}, title = {Welding of girders with thick plates — Fabrication, measurement and simulation}, series = {Journal of Constructional Steel Research}, volume = {Vol. 115}, journal = {Journal of Constructional Steel Research}, issn = {0143-974X}, doi = {10.1016/j.jcsr.2015.08.037}, pages = {407 -- 416}, abstract = {This article presents experimental and numerical results of the fabrication of welded plate girders under workshop conditions. Main concerns are the prediction of imperfections with the aid of simulation tools and/or simplified engineering models. Their impact on the component design is evaluated in a case study. Special focus is put on the effect of residual welding stress. For this, different simplified distributions are compared with results from welding simulation. The findings confirm the thesis that present recommendations on the implementation of weld-induced imperfections must be rated conservative. This suggests that it is necessary to establish new models. Guidance on future problems in this context will be given.}, language = {en} } @inproceedings{PasternakKrauscheLaunert, author = {Pasternak, Hartmut and Krausche, Thomas and Launert, Benjamin}, title = {Welded construction site joints in bridges}, series = {Steel Bridges: Innovation \& New Challenges, 8th International Symposium on Steel Bridges, Istanbul, 2015}, booktitle = {Steel Bridges: Innovation \& New Challenges, 8th International Symposium on Steel Bridges, Istanbul, 2015}, publisher = {Turkish Constructional Steelwork Association (TUCSA)}, address = {Istanbul, Turkey}, isbn = {978-605-65900-2-3}, pages = {315 -- 320}, abstract = {In large steel construction, as in steel bridges, construction site welds are made under difficult conditions such as low temperatures and wind. The comprehensive study will show not only test results from the analysis in the climate chamber (large scale test) with low temperatures (-20°C, -10°C) as well as numerical calculations with the help of welding simulation and non-linear structural analysis. Deflections and temperature are given and compared with traditional engineering models and advises for future problems are presented. For bridge girders with I cross sections, welded thick plates are used and there joining need to be considered precisely. Effect from welding, such as deflections and residual stresses, will have an outcome on the performed component. For welding of thick plates multi-layer welding is used. The edges need to be cut before welding. The preparation process needs to be considered as well as actual joining to have an economic performance. As joint geometry the Z-joint was chosen and investigated. Results from testing as well as from the welding simulation will be shown and compared. Thereby an engineering model will be consulted to evaluate the results. To evaluate the impact of the welding process a FEM load capacity calculation was performed and will be compared with test without imperfections from the joining process.}, language = {en} } @book{NitschkePagelKlassenPasternaketal., author = {Nitschke-Pagel, Thomas and Klassen, Jakob and Pasternak, Hartmut and Launert, Benjamin and Krausche, Thomas}, title = {P 858 - Schweißen dicker Bleche unter Baustellenbedingungen - Beurteilung des Einflusses auf das Tragverhalten von Montagest{\"o}ßen}, publisher = {Verlag und Vertriebsgesellschaft mbH}, address = {D{\"u}sseldorf}, isbn = {978-3-942541-69-5}, abstract = {Beim Aufbau großer Stahlstrukturen im Br{\"u}cken- oder Stahlhochbau wird heute vermehrt auf modulare Fabrikfertigung gesetzt. Ein F{\"u}gen dieser Module auf der Baustelle zu einer Gesamtstruktur ist aber weiterhin notwendig. Als F{\"u}geverfahren wird hier h{\"a}ufig das MAG-Mehrlagenschweißen eingesetzt. Gerade an dicken Blechen stellen Baustellenschweißungen nicht nur besondere Anforderungen an den ausf{\"u}hrenden Betrieb, die Bauleitung und Bau{\"u}berwachung, sondern auch an den Konstrukteur. Wichtig f{\"u}r den Konstrukteur ist die Kenntnis der sich durch Schweißungen einstellenden Schrumpfung der Bauteile, der auftretenden Verz{\"u}ge und Eigenspannungen. Gerade bei Baustellenschweißungen m{\"u}ssen diese Aspekte in der Konstruktionsphase der Einzelkomponenten mit ber{\"u}cksichtigt werden, um die erforderlichen Toleranzen bei der Montage einzuhalten. Eine genaue Kenntnis der durch Schweißungen verursachten Ph{\"a}nomene ist in den Konstruktions- und Montagebetrieben oft nur aus mehrj{\"a}hrigen Erfahrungen vorhanden. Ein grundlegendes, vollst{\"a}ndiges Bild der Abl{\"a}ufe beim Schweißen auf der Baustelle, das es erm{\"o}glicht, dieses Wissen auf neue Konstruktionen zu {\"u}bertragen, fehlt bisher. Insbesondere f{\"u}r die immer {\"o}fter im Br{\"u}cken- und Stahlhochbau eingesetzten h{\"o}herfesten Feinkornbaust{\"a}hle (z.B. S460) ist die Kenntnis des Verhaltens bei Baustellenschweißungen notwendig. Hier setzt der Forschungsantrag an. Mit Hilfe der Schweißsimulation k{\"o}nnen die Auswirkungen von Schweißn{\"a}hten, wie die Entstehung von Verz{\"u}gen und Eigenspannungen am Bauteil, global dargestellt werden. Eine anschließende Struktursimulationen (Festigkeits- und Steifigkeitsberechnungen) mit aus der Schweißsimulation integrierten Ergebnissen bildet die Basis f{\"u}r erg{\"a}nzende Untersuchungen. Montagest{\"o}ße sind außerdem durch Verschmutzung und Witterung negativ beeinflusst. Die Montage kann beispielsweise bei niedrigen Temperaturen unterhalb des Gefrierpunkts durchgef{\"u}hrt werden m{\"u}ssen. Diese Situation wurde in einer Klimakammer simuliert und die Auswirkungen der Umgebungstemperatur bei der Montage auf das Tragverhalten der Verbindung untersucht. F{\"u}r die im Rahmen des Vorhabens untersuchten F{\"a}lle ist kein Einfluss variierender Umgebungstemperaturen bis -10 °C auf die resultierenden Schweißeigenspannungen festzustellen. Der Vergleich von Verzug und Eigenspannung gegen{\"u}ber normativ vorgegeben Toleranzwerten sowie vereinfachten Ingenieurmodellen f{\"u}r die Approximation des Eigenspannungsverlaufs zeigt große Defizite. Bei realit{\"a}tsnaher Implementierung der Eigenspannungen in die Traglastberechnung k{\"o}nnen z.T. große Reserven im Rahmen der nichtlinearen Traglastberechnung ausgenutzt werden.}, language = {de} } @inproceedings{KlassenNitschkePagelDilgeretal., author = {Klassen, Jakob and Nitschke-Pagel, Thomas and Dilger, Klaus and Launert, Benjamin}, title = {Welding of thick steel plates under rough environmental conditions}, series = {7th Asia Pacific IIW International Congress}, booktitle = {7th Asia Pacific IIW International Congress}, pages = {6}, abstract = {Large-scale steel structures are not created on the site. Assembly groups are prefabricated under shop conditions and transported to the site, where the final assembly process takes place. Due to the advantages of manufacturing in a workshop, e.g. the defined ambient conditions, those assembly parts are as big as the transportation possibilities. The final assembling on the site is exposed to the ambient conditions there, which is why assembling on site may be conducted at temperatures below freezing point. Thus high cooling rates induce phase transformations at low temperature and therefore local hardening and are also affecting shrinkage, distortion and residual stresses. Before approving the construction designers need to estimate occurring shrinkage, distortions and residual stresses never knowing what the construction workers on the site really do. It is impossible to supervise or monitor the whole assembling process. That is why it is necessary to think about possible worst cases like clamped welding components, although a clamp was not to be set. Construction workers might apply fixations in order to adhere to specifications, thus creating residual stresses which may have a significant impact on the fatigue behaviour of a construction. In this paper large-scale specimens are investigated. These were derived from actual bridge girders and welded in a climatic chamber simulating different cooling rates on the site (up to -10°C). Welding experiments were accompanied by distortion and temperature field monitoring. Afterwards residual stresses were determined using x-ray diffraction. Finally welding distortions and residual stresses are calculated using numerical welding simulation. The simulated and experimental results are compared.}, language = {en} } @inproceedings{LaunertRhodePasternaketal., author = {Launert, Benjamin and Rhode, Michael and Pasternak, Hartmut and Kannengießer, Thomas}, title = {Welding residual stresses in high-strength steel. Experimental results}, series = {The International Colloquium on Stability and Ductility of Steel Structures}, booktitle = {The International Colloquium on Stability and Ductility of Steel Structures}, editor = {Dubina, Dan and Ungureanu, Viorel}, edition = {2016 edition}, publisher = {Ernst \& Sohn}, isbn = {978-92-9147-133-1}, pages = {517 -- 524}, abstract = {This article presents the latest results of an ongoing national research project on improved models for the prediction of welding residual stresses of thick-plated welded I-girders. The experimental program is presented and the importance of different influencing factors on the residual stresses is discussed in detail. All results are compared for mild (S355J2+N) and high strength (S690QL) steel. Finally, conclusions for further works are drawn.}, language = {en} } @inproceedings{PasternakLaunertKannengiesseretal., author = {Pasternak, Hartmut and Launert, Benjamin and Kannengießer, Thomas and Rhode, Michael}, title = {Residual stresses and imperfections in welded high-strength I-shape members}, series = {Insights and Innovations in Structural Engineering, Mechanics and Computation, Proceedings of the Sixth International Conference on Structural Engineering, Mechanics and Computation, Cape Town, South Africa, 5-7 September 2016}, booktitle = {Insights and Innovations in Structural Engineering, Mechanics and Computation, Proceedings of the Sixth International Conference on Structural Engineering, Mechanics and Computation, Cape Town, South Africa, 5-7 September 2016}, editor = {Zingoni, Alphose}, publisher = {Taylor \& Francis}, address = {London}, isbn = {978-1-138-02927-9}, pages = {403 -- 404}, abstract = {This article addresses the imperfections caused by the weld assembly in I-shape sections made of two structural steel grades. Load influencing imperfections are assumed as deviations from the ideal shape (e.g. bending distortion) and longitudinal residual stresses. The quality of a numerically aided design of components exposed to either compression and/or bending is significantly affected, depending on these parameters [1]. The Eurocode provides robust simplified models. As a result, the Ultimate Limit State (ULS) is approached on a conservative basis. The following investigations are aimed at providing further guidance on these values in component-like specimens. The long term goal is an improved understanding of the load-bearing capacity of such sections. As a first step in this process, the experimental and corresponding numerical studies are presented.}, language = {en} } @inproceedings{LaunertRhodeKrommetal., author = {Launert, Benjamin and Rhode, Michael and Kromm, Arne and Pasternak, Hartmut and Kannengießer, Thomas}, title = {Residual Stress Influence on the Flexural Buckling of Welded I-Girders}, series = {Residual Stresses 2016 - ICRS-10}, booktitle = {Residual Stresses 2016 - ICRS-10}, editor = {Holden, Thomas M. and Mur{\´a}nsky, Ondrej and Edwards, Lyndon}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, isbn = {978-1-94529116-6}, doi = {10.21741/9781945291173-19}, pages = {109 -- 114}, abstract = {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.}, language = {en} } @inproceedings{KrommRhodeLaunertetal., author = {Kromm, Arne and Rhode, Michael and Launert, Benjamin and Dixneit, Jonny and Kannengießer, Thomas and Pasternak, Hartmut}, title = {Combining Sectioning Method and X-Ray Diffraction for Evaluation of Residual Stresses in Welded High Strength Steel Components}, series = {Residual Stresses 2016 - ICRS-10}, booktitle = {Residual Stresses 2016 - ICRS-10}, editor = {Holden, Thomas M. and Mur{\´a}nsky, Ondrej and Edwards, Lyndon}, publisher = {Materials Research Forum LLC}, address = {Millersville, PA}, isbn = {978-1-94529116-6}, doi = {10.21741/9781945291173-28}, pages = {163 -- 168}, abstract = {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.}, language = {en} } @misc{LaunertSzczerbaGajewskietal., author = {Launert, Benjamin and Szczerba, Radosław and Gajewski, Marcin and Rhode, Michael and Pasternak, Hartmut and Giżejowski, Marian}, title = {The buckling resistance of welded plate girders taking into account the influence of post-welding imperfections - Part 1: Parameter study}, series = {Materials Testing}, volume = {59}, journal = {Materials Testing}, number = {1}, issn = {0025-5300}, doi = {10.3139/120.110964}, pages = {47 -- 56}, abstract = {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.}, language = {en} } @misc{LaunertRhodeKrommetal., author = {Launert, Benjamin and Rhode, Michael and Kromm, Arne and Pasternak, Hartmut and Kannengießer, Thomas}, title = {Measurement and numerical modeling of residual stresses in welded HSLA component-like I-girders}, series = {Welding in the World}, volume = {61}, journal = {Welding in the World}, number = {2}, issn = {0043-2288}, doi = {10.1007/s40194-016-0413-x}, pages = {223 -- 229}, abstract = {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.}, language = {en} } @misc{PasternakLaunertKannengiesseretal., author = {Pasternak, Hartmut and Launert, Benjamin and Kannengießer, Thomas and Rhode, Michael}, title = {Advanced Residual Stress Assessment of Plate Girders Through Welding Simulation}, series = {Procedia Engineering}, volume = {172}, journal = {Procedia Engineering}, issn = {1877-7058}, doi = {10.1016/j.proeng.2017.02.013}, pages = {23 -- 30}, abstract = {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.}, language = {en} }