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 - 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 - 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 - GEN A1 - Wang, Jian A1 - Li, Zheng A1 - Euler, Mathias T1 - Investigation on shear buckling of steel welded I-section beams with reinforced web openings T2 - ce/papers KW - Shear buckling KW - Reinforced web openings KW - Steel plate girder KW - 3D Laser Scanning Y1 - 2023 U6 - https://doi.org/10.1002/cepa.2361 VL - 6 IS - 3-4 SP - 1754 EP - 1760 ER - TY - CHAP A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Partov, Doncho ED - Jendželovský, Norbert ED - Grmanová, Alžbeta T1 - Influence of statistical size effect in steel on structural safety T2 - Proceedings of 16th International Conference on New Trends in Statics and Dynamics of Buildings N2 - This paper present the investigation of the statistical size effect in steel structure and the corresponding reliability. This study described the randomness of material properties through two different ways. These two proposed simulation methods, which are an extension and supplement to traditional simulation methods, can effectively simulate the statistical size effect for the tensile and flexural components in steel structures. The test results show that the variations of the yield and tensile strength increase with the decreasing specimen volume. Besides, the structural component strength is not only related to the specimen volume, but also the stress distribution. It is found by studying the influence of statistical size effect on structural reliability that the strength, which is obtained by small specimens through statistical analysis in the laboratory, is no more accurately applicable to large construction. The core idea is that the stochastic material proper-ties are directly embedded in mechanical calculations to develop a more accurate and economical design method for steel structure. KW - Statistical size effect KW - Steel structure KW - Stochastic material model KW - Stochastic FEM KW - Structural safety Y1 - 2018 UR - http://www.newtrends.sk/dokumenty/proceedings_2018.pdf SN - 978-80-227-4845-2 PB - Slovak University of Technology CY - Bratislava ER - TY - GEN A1 - Wang, Jian A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Euler, Mathias T1 - Querkrafttragfähigkeit von Wellstegträgern mit versteiften quadratischen Stegöffnungen T2 - Bauingenieur N2 - Die Ergebnisse aus drei Traglastversuchen und einer umfangreichen numerischen Parameterstudie (FE-Berechnungen) zum Tragverhalten von Wellstegträgern mit quadratischen Stegöffnungen werden vorgestellt. Es werden versteifte Stegöffnungen mit einem umlaufenden Versteifungskranz betrachtet. In der Parameterstudie werden die Einflüsse der Stegöffnungsgeometrie, der Trägergeometrie und der Position der Stegöffnung auf die Querkrafttragfähigkeit der Wellstegträger untersucht. KW - Wellstegträger KW - Stegöffnung KW - Versteifungskranz Y1 - 2023 U6 - https://doi.org/10.37544/0005-6650-2023-11-31 SN - 0005-6650 VL - 98 IS - 11 SP - 343 EP - 353 ER - TY - GEN A1 - Liu, Wen-Cai A1 - Dong, Jie A1 - Zhang, Ping A1 - Zheng, Xing-Wei A1 - Ding, Wen-Jiang A1 - Li, De-Hui A1 - Korsunsky, Alexander M. T1 - Smooth and notched fatigue performance of aging treated and shot peened ZK60 magnesium alloy T2 - Journal of materials research Y1 - 2010 SN - 2044-5326 VL - 25 IS - 7 SP - 1375 EP - 1387 ER - TY - GEN A1 - Li, Zheng A1 - Pasternak, Hartmut T1 - Statistischer Maßstabseffekt und seine Bedeutung für die Zuverlässigkeit im Stahlbau,Teil 1 – Modell und Versuch T2 - Bautechnik Y1 - 2020 U6 - https://doi.org/10.1002/bate.202000030 VL - 97 IS - 11 SP - 766 EP - 772 ER - TY - GEN A1 - Li, Zheng A1 - Loebjinski, Maria A1 - Pasternak, Hartmut T1 - Statistischer Maßstabseffekt und seine Bedeutung für die Zuverlässigkeit im Stahlbau, Teil 2‐ Zuverlässigkeitsanalyse T2 - Bautechnik Y1 - 2020 U6 - https://doi.org/10.1002/bate.202000031 VL - 97 IS - 11 SP - 773 EP - 779 ER - TY - GEN A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Robra, Jörgen T1 - Tragverhalten von Wellstegträgern mit kreisförmigem Öffnungskranz T2 - Bauingenieur Y1 - 2021 U6 - https://doi.org/10.37544/0005-6650-2021-04-50 SN - 0005-6650 VL - 96 IS - 4 SP - 114 EP - 120 ER - TY - GEN A1 - Wang, Jian A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Euler, Mathias T1 - Shear Buckling Behavior of Tapered Steel Plate Girders with Sinusoidally Corrugated Webs T2 - ce/papers KW - Plate girders KW - Shear Buckling KW - Tapered plate girders KW - Sinusoidal Corrugated Webs KW - Résal effect Y1 - 2023 U6 - https://doi.org/10.1002/cepa.2534 SN - 2509-7075 VL - 6 IS - 3-4 SP - 1787 EP - 1792 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 - TY - GEN A1 - Dong, Jiwu A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Ciupack, Yvonne T1 - Reinforcement of Fatigue Damaged Steel Structures Using CFRP Lamellas - Part 3: Numerical Simulation T2 - Bauingenieur Y1 - 2020 SN - 0005-6650 SN - 1436-4867 VL - 96 IS - 10 SP - 362 EP - 368 ER - TY - GEN A1 - Li, Zheng A1 - Pasternak, Hartmut T1 - Experimental and numerical investigations of statistical size effect in S235JR steel structural elements T2 - Construction and Building Materials N2 - This paper presents the analysis of the statistical size effect in steel structural elements using the stochastic finite element (FE) method. The three-dimensional random field theory is applied to simulate the uncertainty of a nonlinear material. The proposed approach, which combines the discrete random field describing the randomness of the material properties via Monte Carlo simulations, is used for computing the bearing capacity variability of the steel structures. In addition, the mapping interpolation method makes it possible to separate the random field mesh and FE model mesh. The three-dimensional random field for the material properties is established according to the yield strength with a lognormal distribution based on reasonable assumptions, and the corresponding random field parameters are studied. Finally, the results of experimental investigation and simulations are compared based on the tensile and bending tests, and they indicate that the statistical size effect cannot be overlooked in S235JR steel structural elements and that the use of stochastic FE in the analysis of the statistical size effect has tremendous potential. KW - 3D Random field KW - Stochastic finite element method KW - Mapping interpolation method KW - Statistical size effect KW - Steel structural elements Y1 - 2019 U6 - https://doi.org/10.1016/j.conbuildmat.2019.02.106 SN - 0950-0618 VL - 206 SP - 665 EP - 673 ER - TY - GEN A1 - Li, Zheng A1 - Pasternak, Hartmut A1 - Ciupack, Yvonne ED - Zingoni, Alphose T1 - Artificial neural network prediction of bearing capacity of welded columns based on simplified welding simulations 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 - 1219 EP - 1223 PB - Taylor & Francis Group CY - London 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 - Li, Zheng A1 - Pasternak, Hartmut T1 - Statistical size effect of flexural members in steel structures T2 - Journal of Constructional Steel Research N2 - This paper presents the results of theoretical and experimental investigations on the statistical size effect (SSE) of flexural members in steel. The chain of bundle model is developed, which is based on a stochastic material model by Weibull and lognormal distribution. Furthermore, this model is embedded into the finite element method (FEM) software for the analysis of a complicated structure with a stress gradient. In order to determine the stochastic material model parameters, uniaxial tensile tests were carried out based on specimens using the same steel with different sizes. By comparing the experimental and simulation results, the material parameters could be analyzed based on the relationship between the specimen sizes and strength. Moreover, the 3-point and 4-point bending tests were performed and simulated with the developed model. The experimental and simulation results demonstrate that the SSE also exists in the flexural member, and the equivalent yield stress is closely related to the stress distribution and volume of the structure component. Y1 - 2018 U6 - https://doi.org/10.1016/j.jcsr.2018.01.025 SN - 0143-974X VL - 144 SP - 176 EP - 185 ER - TY - GEN A1 - Li, Zheng A1 - Xu, Siying A1 - Geißler, Karsten A1 - Wang, Jian A1 - Pasternak, Hartmut T1 - Developed numerical Analysis of Residual Stress caused by Welding and Cutting in Steel Structures T2 - ce/papers N2 - The welding and flame‐cutting process in the steel construction are commonly used, especially for the bridge structure. Some experiments about welding and cutting have been done separately by some researchers. The results from the experiments were also compared with the results from the numerical simulation under 3D or 2D models. The agreements between those results are as good as they predicted. Therefore, the numerical simulation is a better way to analyze the quality of the steel construction after welding and cutting without time‐consuming and a large amount of cost. But there are only a few research about the numerical simulation and the some of them are aimed to verify the experiments. In this study, the calculation about the residual stresses after welding and thermo‐cutting are considered from 3D‐model into 2D‐Model. The heat source model is simply regarded as curves of time and welding energy with the algorithm methods. And no matter the change of the parameters of the model and the heat source, the heat transfer and the residual stresses can be calculated with the 2D models as fast as possible. By the means of the finite element software Abaqus, the I‐profiles are easy to receive the job results with the input parameters. The influence of the welding and cutting process are visual and direct. KW - Welding KW - Flame cutting KW - Numerical simulation KW - Residual stress KW - Steel structures Y1 - 2023 U6 - https://doi.org/10.1002/cepa.2601 SN - 2509-7075 VL - 6 IS - 3-4 SP - 1507 EP - 1512 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 - GEN A1 - Jäger-Cañás, Andreas A1 - Li, Zheng A1 - Pasternak, Hartmut T1 - Axial buckling behavior of welded ring-stiffened 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 SN - 978-0-429-32024-8 SN - 978-0-367-33503-8 U6 - https://doi.org/10.1201/9780429320248 SP - 556 EP - 563 PB - CRC Press CY - London ET - 1st Edition ER - TY - GEN A1 - Li, Zheng A1 - Zhang, Qiulei A1 - Shi, Fei A1 - Wang, Jian A1 - Pasternak, Hartmut T1 - Geometric Properties of Steel Components with Stability and Fatigue Risks Using 3D-Laser-Scanning T2 - Buildings N2 - Nowadays, 3D laser scanning technology is extensively employed in laboratory investigations of steel structural components, providing accurate geometric dimensions to reduce uncertainties caused by indeterminate geometry in experimental results. It is often used in conjunction with the Finite Element (FE) Method and analytical solutions, which are more accurate deterministic operators in the research on steel structures. However, establishing a common methodological framework for transferring or mapping 3D-scanned information into finite element models for complex steel structures with stability and fatigue risks remains an ongoing task. In light of this, this study has developed a 3D scanning platform capable of obtaining accurate geometric dimensions for various types of steel components. Different coordinate systems and point cloud mapping algorithms have been established for different types of components to construct actual finite element models with initial imperfections. The feasibility of the self-developed 3D scanning platform and finite element modelling has been validated through three experimental cases: weld details, steel girders, and cylindrical shells. The research findings demonstrate that the captured point cloud can be automatically processed and corrected using the developed algorithm. The scanned data can then be input into the numerical model using various mapping algorithms tailored to the specific geometric properties of the specimens. The differences between the experimental test results and the simulated results obtained from the 3D-scanned finite element models remain within a small range. The self-developed 3D scanning platform and finite element modelling technique effectively capture the actual dimensions of different steel components, enabling the prediction of their stability and fatigue risks through numerical simulations. KW - 3D laser scanning KW - steel structures KW - geometric properties KW - stability KW - fatigue Y1 - 2024 U6 - https://doi.org/10.3390/buildings14010168 SN - 2075-5309 VL - 14 IS - 1 ER - TY - GEN A1 - Wang, Jian A1 - Li, Zheng A1 - Robra, Jörgen A1 - Pasternak, Hartmut A1 - Euler, Mathias T1 - Investigation on Shear Buckling of Corrugated Web Beams with Reinforced Web Openings T2 - ce/papers N2 - Corrugated web beams are welded I‐sections with thin‐walled sinusoidal corrugated webs and flanges made of wide flat steel that have been developed as an alternative to steel girders with flat webs. In comparison with hot‐rolled or welded I‐beams with flat webs, corrugated web beams are connected with considerable material savings and fully automated production. Assuming the same load‐bearing capacity, corrugated web beams are lighter than those with a flat web, since the corrugated web beams can often be loaded up to their plastic resistance without reinforcement of the web. The research on the load‐bearing behavior of corrugated web beams without web openings is relatively mature. However, the resistance of corrugated web beams with reinforced web openings, as they are often used in buildings for installations, has not well experimentally been investigated, yet. This paper deals with the shear resistance of corrugated web beams with reinforced square web openings. Three specimens of different geometry with two square web openings were tested. The experiments are compared with a Finite Element Analysis by Abaqus® and with an analytical model allowing simplified calculation. Both models can relatively accurately calculate the shear resistance. The experimental and numerical results show that the increase of the shear resistance of perforated corrugated web beams depends on the wall‐thickness and the steel grade of the web opening reinforcement. KW - Corrugated web beams KW - square web openings KW - ring stiffener KW - local shear buckling KW - experimental investigation KW - finite element analysis Y1 - 2022 U6 - https://doi.org/10.1002/cepa.1800 SN - 2509-7075 VL - 5 IS - 4 SP - 628 EP - 634 ER -