The design practice of structural engineering is currently undergoing a considerable amount of fundamental change. For example, in recent years, limit state design has been introduced in Europe for the design of steel structures, and load and resistance factor design has become mandatory in the United States. However, other more dramatic changes in the practice of structural steel design attributable to a shift in the design philosophy as evidenced by the introduction of numerous new codes and standards that now require design for stability and ductility response. This paper discusses the yield mechanism forms of different solutions of the connections of trapezoidal stiffeners and cross beams for orthotropic steel plates.
Before the 1960s the ductility notion was used only for characterizing the material behaviour. After Baker's research on plastic design, this concept has been extended to the structural level. This paper provides a general overview of ductility. The paper examines the behaviour of material ductility, cross-section ductility and member ductility separately, then it studies how the sum of the effects of all these ductilities affect the structural ductility. The effect of the different ductilities can be built into the structural behaviour through an interactive hinge model. The model of the interactive hinge also takes into consideration the effects of the residual stresses and deformations, the strain hardening and the plate buckling.
The structure and mechanical properties of austempered ductile iron (ADI) depend strongly on the mechanism and kinetics of phase transformations proceeding successively during the austempering heat treatment
Authors:F. Mata Cabrera, J. Tejero Manzanares, I. Hanafi, A. B. Arenas, I. Garrido, V. Toledano, and M. L. Rubio
Mechanical properties of ductile materials are very sensitive to environmental conditions in particular temperature. The paper shows the results obtained in the simultaneous testing of 5182 H111 Aluminium alloy, S275JR Carbon Steel and F114 Carbon Steel specimens using conventional methods and thermography. The infrared thermography was used to quantify deformation localization zones, also to relate the temperature changes of the specimens, continuously recorded by thermography, with the load extension diagram. It enables to predict reaching the critical stresses which cause the appearance of fractures and to define the criteria for determining the maximum sample temperature alteration in the field of elastic and elastic-plastic strains. Infrared thermography was found to be an efficient tool for investigating the deformation and damage scenario under tensile loading.
In the Paleozoic and Mesozoic rocks of the Bükk Mountains the imprints of a polyphase deformation and an anchi-epizonal metamorphism were observed. The physical conditions of this metamorphism were the same as that of the earliest, ductile deformation phase. The imprints of later deformation phases can generally be distinguished by their tectonic style. Our investigation was focused on the style of folding and on the different textural elements of limestone which developed during the early deformation phase. According to lithologic conditions and geographical position, the folds show a certain style variety. The multilayer fold geometry depends on the thickness ratio and the competence contrast between the layers. In the occurrence of different textural patterns the position within a fold and the pre-deformational grain size play an important role. The main deformation mechanism in the fine-grained matrix was pressure solution, while coarse-grained crystal aggregates show signs of dynamic recrystallization, which in some cases leads as far as the development of mylonitic texture and strong lattice-preferred orientation. The differences in spatial style of the same rock types provide a basis for defining tectofacial units in the eastern part of the Bükk Mts.
In order to subdivide members into ductility classes is important to know the slenderness factor “
”, which can be defined as the ratio between critical tension that brings local instability of the compressed flange or the flexural-torsional instability and the yield tension. The current paper deals with the redefinition of coefficients in the expression of the over-strength factor “
” proposed by the new seismic Italian code OPCM 3274 for hot rolled and welded double-T sections and with the introduction of a new expression of the same parameter for other members with different shape like rectangular, square and circular hollow sections and slender C sections.
Authors:Ágnes Skultéti, Tivadar M. Tóth, István János Kovács, Edit Király, and Judit Sándorné Kovács
“water” in the crystal lattice of quartz significantly influences its brittle and ductile behavior reduces its mechanical strength and resistivity and enhances its ductile deformation at low temperatures (200–300 °C; Griggs and Blacic 1965 ; Blacic 1975