Maria Kotelko
University of Łódź
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Featured researches published by Maria Kotelko.
Thin-walled Structures | 2004
Maria Kotelko
Abstract The present paper is devoted to the recent results of research in the area of load-capacity and post-failure behaviour of thin-walled beams and columns (among them thin-walled cold-formed profiles). It deals with ultimate load and collapse of box-section girders (tubes) of different cross-sections under bending, as well as of lipped and plain channel-section beam-columns. The paper contains the presentation of theoretical analysis and experimental investigation of plastic mechanisms of failure and collapse behaviour of these thin-walled sections. The short review of results obtained in recent years in general precedes those obtained by the Department of Strength of Materials and Structures, TUL. The problem of post-failure behaviour is solved using the rigid-plastic theory adopted and modified for the purposes of the solution taking into consideration strain-hardening of the member’s material. On the basis of experimental investigations theoretical models of plastic mechanisms of failure are produced for different sections. Theoretical analysis is based on the principle of virtual velocities. The problem is solved in an analytical–numerical way. The particular attention has been paid to the influence of the strain-hardening of the material after yielding upon the collapse structural behaviour and also to the influence of cross-section shape and dimensions on the character of collapse. The upper-bound estimation of the load-carrying capacity of analysed thin-walled sections by combining results of non-linear, elastic post-buckling analysis with the results of plastic mechanism analysis is carried out. Results are presented in diagrams showing post-failure curves as well as curves representing structural behaviour in the whole range of loading up to and beyond the ultimate load. Some results are compared with experimental results and those obtained from FE analysis. A comparison of lower- and upper-bound estimation of the load-carrying capacity is discussed and illustrated in diagrams. Conclusions dealing with the influence of strain-hardening phenomenon displayed by the material upon the load-carrying capacity and collapse behaviour of examined sections are derived. Also conclusions concerning different upper- and lower-bound estimations of the load-carrying capacity of analysed sections are presented.
Thin-walled Structures | 2000
Maria Kotelko; T.H Lim; J. Rhodes
Abstract The results of a program of experiments set up to explore the post-failure behaviour of box section beams subjected to pure bending are presented. Rectangular and trapezoidal cross-section beams were loaded up to and beyond collapse in a four-point bending configuration. Load–deflection graphs were recorded and the details of the observed plastic collapse mechanisms were noted. Experimental collapse curves are compared with those derived from theoretical models of plastic collapse mechanisms based upon rigid–plastic theory.
Thin-walled Structures | 1993
Maria Kotelko; Marian Królak
Abstract Plastic mechanisms of failure of triangular cross-section girders subjected to pure bending are considered in this paper. Theoretical models of four basic plastic mechanisms observed during preliminary experimental model investigation are described. Theoretical analysis is carried out using basic assumptions of the general rigid plastic theory and particular assumptions concerning thin-walled structures. The total energy of plastic deformation as well as the bending moment of the global plastic hinge are formulated. Example of numerical results relating to one of considered plastic mechanisms is presented.
Thin-walled Structures | 2001
Marian Królak; Zbigniew Kolakowski; Maria Kotelko
Abstract The paper contains an analysis of the influence of non-uniformity and eccentricity of compressive loads on global and local buckling, on interactive buckling, and on the load-carrying capacity of thin-walled columns. Isotropic and orthotropic tubular columns of regular hexagonal cross-section have been examined. Equilibrium equations for the first and the second order non-linear approximation have been solved using the asymptotic Byskov–Hutchinson method. Numerical calculations have been performed for numerous different loading modes of isotropic columns and also for several loading modes of orthotropic columns. The results are presented in diagrams with some conclusions.
COMPUTER METHODS IN MECHANICS (CMM2017): Proceedings of the 22nd International Conference on Computer Methods in Mechanics | 2018
Viorel Ungureanu; Maria Kotelko; Łukasz Borkowski; Jan Grudziecki
Thin-walled cold-formed steel structures are usually made of members of class 4 cross-sections. Since these sections are prematurely prone to local or distortional buckling and due to the fact they do not have a real post-elastic capacity, the failure at ultimate stage of those members, either in compression or bending, always occurs by forming a local plastic mechanism. The present paper investigates the evolution of the plastic mechanisms and the possibility to use them to characterise the ultimate strength of short thin-walled cold-formed steel members subjected to eccentric compression about minor axis, particularly for members with lipped channel cross-section. Five different types of plastic mechanisms for members in compression with different eccentricities are identified and examined on the basis of FE numerical simulations. Preliminary results of experimental validation of numerical results are presented. The research is based on previous studies and some new investigations of the authors.Thin-walled cold-formed steel structures are usually made of members of class 4 cross-sections. Since these sections are prematurely prone to local or distortional buckling and due to the fact they do not have a real post-elastic capacity, the failure at ultimate stage of those members, either in compression or bending, always occurs by forming a local plastic mechanism. The present paper investigates the evolution of the plastic mechanisms and the possibility to use them to characterise the ultimate strength of short thin-walled cold-formed steel members subjected to eccentric compression about minor axis, particularly for members with lipped channel cross-section. Five different types of plastic mechanisms for members in compression with different eccentricities are identified and examined on the basis of FE numerical simulations. Preliminary results of experimental validation of numerical results are presented. The research is based on previous studies and some new investigations of the authors.
Thin-walled Structures | 2008
Maria Kotelko; Katarzyna Kowal-Michalska; Tomasz Kubiak; Zbigniew Kolakowski; R. Gradzki
Thin-walled Structures | 2007
Martin Macdonald; J. Rhodes; Maria Kotelko
Thin-walled Structures | 2012
Maria Kotelko; Radoslaw J. Mania
Thin-walled Structures | 2007
Maria Kotelko; K. Kowal-Michalska; J. Rhodes
Thin-walled Structures | 2017
Maria Kotelko; Paweł Lis; Martin Macdonald