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 - 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 - 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 - 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 - 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 - 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 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 - 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 -