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 - 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 - 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 - TY - CHAP A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - The Influence of Geometrical and Welding Imperfections on the Strength of Stiffened Structures T2 - High Performance Steel Structures Research Council (HPSSRC), Delft, Netherlands, 2018 N2 - The strength calculation of stiffened plates and shells via finite element simulation has been part of the state of the art for a long time. Geometrical nonlinearities as well as the nonlinear material behavior are considered within the calculation. To simplify, both types of imperfections, geometrical and structural ones, are mostly combined in these strength calculations being considered as equivalent geometrical imperfections. Values for standard cases are included in EN 1993-1-5 in case of plated structures or 1-6 in case of shells. A second possibility is the separate definition of fabrication tolerances and residual stresses, as far as they are known. With increasing complexity of the structure, less information are however available on geometrical and particularly structural imperfections. Nevertheless, by means of a more realistic consideration of these values, the actual ultimate load can be determined significantly more exactly and the performance of high performance steel structures is increased. In the investigated cases, deformations and stresses arise mainly due to welding. Therefore, the topic of this article is the application of an analytical numerical hybrid model for predicting imperfections induced by welds. This is presented on an example of a stiffened steel structure and a subsequent ultimate load calculation. At the beginning the analytical model, its physical basis as well as the physical interrelationships are introduced and explained. This is followed by the explanation of the coupling procedure between the analytical model and the numerical calculation for the calculation of weld-induced deformations and residual stresses. The significance of the hybrid model is proven by means of a few sample applications. For a realistic determination of the weld imperfections in the investigated stiffened structure, the coupled hybrid model is used afterwards. An ultimate load analysis gives information about the load carrying behavior under axial loading. The results are compared with the results of an ultimate load analysis from a literature example assuming different eigenvalues with different scaling. The results underline the potential additional utilization of load bearing capacity by this new approach. KW - Welding KW - Stresses KW - Strains KW - Imperfections KW - Stiffened Structures KW - Distortions Y1 - 2018 UR - https://www-docs.b-tu.de/fg-stahlbau/public/Fachgebiet_Stahlbau/publikationen/Workshop_Proceedings_of_HPSSRC-updated_cs.pdf SP - 191 EP - 201 ER - TY - GEN A1 - Tankova, Trayana A1 - Silva, Luís Simões da A1 - Balakrishnam, Marimuthu A1 - Rodrigues, Dulce A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Tun, Tin Yadanar T1 - Residual stresses in welded I section steel members T2 - Engineering Structures N2 - Residual stresses have major influence on the stability of steel members. It is well-known that, due to the differences in manufacturing procedures, the residual stresses for welded and hot – rolled members are rather different. In the same way, despite several studies on residual stresses distribution and magnitude for hot-rolled members were already done, for prismatic and tapered welded I section steel members the investigation is still very scarce. In the current work, an experimental programme on the buckling resistance of tapered members, with different tapering ratios and section heights, was conducted and residual stress measurements were carried out using the sectioning method. Numerical simulations of the heat input during welding were also performed in order to predict the residual stress fields. A statistical analysis of the residual stresses distribution for welded I section members was performed, using the experimental and numerical results, as well as literature data. Systematized information on residual stresses distribution and magnitude was generated and some guidelines for the statistical characterization of residual stresses in welded members were proposed. KW - Residual stresses KW - Welded sections KW - Steel KW - Eurocode 3 KW - Stability KW - Welding simulation KW - I section KW - Experimental tests Y1 - 2019 U6 - https://doi.org/10.1016/j.engstruct.2019.109398 SN - 0141-0296 VL - 197 ER - TY - GEN A1 - Doynov, Nikolay A1 - Stapelfeld, Christoph A1 - Michailov, Vesselin A1 - Pasternak, Hartmut A1 - Launert, Benjamin ED - Sommitsch, Christof ED - Enzinger, Norbert ED - Mayr, Peter T1 - Distortion analysis of large scaled welded structures T2 - Mathematical Modelling of Weld Phenomena 12 : selected peer reviewed papers from the 12th International Seminar Numerical Analysis of Weldability : September 23-26, 2018, Graz, Schloss Seggau - Austria N2 - The work presents an innovative approach for simulation of welding induced distortions, which allows taking into consideration the local effects of the welding process as well as the global interactions in the structure. The approach bases on an integration of analytical and numerical calculation’s procedures in a hybrid model, realized with the aid of the inherent strain concept. The analytical procedure calculates the shrinkage strain components and area of the plastic deformed zone, caused by welding. The calculated strains are then transferred to the global finite element model in order to predict the distortions and stresses in the structure after every welding stage, as well as their final state. The consideration of welding scenarios, weld sequence, clamping conditions and the assembling stages is done by taking into account the intermediate variation of the strain state during the manufacturing steps. The article gives the theoretical basis of the analytical model. The consideration of the essential physical relations is put into discussion. The application of the model is illustrated on complex structures. Its reliability and practicability are demonstrated by means of a validation study. Y1 - 2019 SN - 978-3-85125-615-4 U6 - https://doi.org/10.3217/978-3-85125-615-4 SP - 254 EP - 280 PB - Verlag der Technischen Universität Graz CY - Graz ER - TY - GEN A1 - Launert, Benjamin A1 - Li, Zheng A1 - Pasternak, Hartmut ED - Zingoni, Alphose T1 - Development of a new method for the direct numerical consideration of welding effects in the component design of welded plate girders T2 - Advances in engineering materials, structures and systems : innovations, mechanics and applications : proceedings of the 7th International Conference on Structural Engineering, Mechanics, and Computation (SEMC 2019), September 2-4, 2019, Cape Town, South Africa Y1 - 2019 SN - 978-1-138-38696-9 SP - 1143 EP - 1147 PB - Taylor & Francis Group CY - London ER - TY - GEN A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Pasternak, Hartmut A1 - Doynov, Nikolay A1 - Michailov, Vesselin T1 - Improve load capacity calculations by considering realistic imperfections induced by welding for plates and shells T2 - Stability and ductility of steel structures 2019 : proceedings of the International Colloquia on Stability and Ductility of Steel Structures (SDSS 2019), September 11-13, 2019, Prague, Czech Republic Y1 - 2019 UR - https://www.b-tu.de/fg-stahlbau/publikationen/veroeffentlichungen SN - 978-0-367-33503-8 SP - 1059 EP - 1067 PB - CRC Press CY - Boca Raton ER - TY - GEN A1 - Pasternak, Hartmut A1 - Li, Zheng A1 - Stapelfeld, Christoph A1 - Jäger-Cañás, Andreas A1 - Launert, Benjamin T1 - Considering realistic weld imperfections in load bearing capacity calculations of ring-stiffened shells using the analytical numerical hybrid model T2 - Stability and Ductility of Steel Structures 2019 : Proceedings of the International Colloquia on Stability and Ductility of Steel Structures (SDSS 2019), September 11-13, 2019, Prague, Czech Republic Y1 - 2019 SN - 978-0-429-32024-8 SN - 978-0-367-33503-8 U6 - https://doi.org/10.1201/9780429320248 SP - 882 EP - 889 PB - CRC Press CY - London ET - 1st Edition ER - TY - BOOK A1 - Pasternak, Hartmut A1 - Stapelfeld, Christoph A1 - Launert, Benjamin A1 - Michailov, Vesselin A1 - Doynov, Nikolay T1 - Ermittlung der Tragfähigkeit neuartiger stählerner Schalenbauwerke unter realitätsnaher Berücksichtigung des Schweißverzugs Y1 - 2020 SN - 978-3-946885-89-4 PB - Forschungsvereinigung Stahlanwendung e. V. CY - Düsseldorf ER - TY - GEN A1 - Wang, Jian A1 - Euler, Mathias A1 - Pasternak, Hartmut A1 - Li, Zheng A1 - Krausche, Thomas A1 - Launert, Benjamin T1 - Bending capacity of single and double-sided welded I-section girders: Part 1: Experimental investigations T2 - Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems : Proceedings of The Eighth International Conference on Structural Engineering, Mechanics and Computation, 5-7 September 2022, Cape Town, South Africa N2 - The lateral-torsional buckling resistance of welded steel girders is affected by their residual stresses and geo-metric imperfections. Generally, both influences are mainly controlled by the manufacturing process, in partic-ular the welding of the girder. This paper presents experimental investigations on four laterally unbraced welded steel girders with thin-walled I-sections, whose flange-to-web junctions are welded from one or two sides to evaluate the fabrication influence. The investigations include lateral-torsional buckling tests under combined bending and torsion loading caused by three-point bending due to an eccentric vertical single force. The geometric imperfections of the welded test girders are determined by 3D laser scanning. The test results show that the influence of the geometric imperfections and the residual stresses on the lateral-torsional buck-ling resistance is limited for the tested girders. KW - Experimental investigations KW - single and double-sided welds KW - imperfections KW - lateral-torsional buckling KW - 3D laser scanning Y1 - 2022 SN - 978-1-00-334845-0 U6 - https://doi.org/10.1201/9781003348443-159 SP - 975 EP - 980 PB - CRC Press CY - Boca Raton ER -