High-strength steel: implications of material and geometric characteristics on inelastic flexural behavior (original) (raw)
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New Trends in the evaluation of available ductility of steel members
2000
ΑBsTRΑcT: The duοtility of steel Ι-seοtion membeΙs is determined for monotonic and seismic loads usins the coΙΙapse plastia mechanisms, Ιη addition, fractuΙe duοtility is defined considering the rotation corΙesponding the cracking ofbuckΙed flanges, The influence of different faοtoΙs is considered: gΙavitationat Ιoads, earthqυake typ€ , stΙain rate and cyclia loads. Simplified relationships for practicaι desiμ are given.
New trends in the evaluation of available ductilitv of steel members
of Structural Aιιιlysis αnd Design, UniνersirJ ofNapιes' kaιy ΑBsTRΑcT: The duοtility of steel Ι-seοtion membeΙs is determined for monotonic and seismic loads usins the coΙΙapse plastia mechanisms, Ιη addition, fractuΙe duοtility is defined considering the rotation corΙesponding the cracking ofbuckΙed flanges, The influence of different faοtoΙs is considered: gΙavitationat Ιoads, earthqυake typ€ , stΙain rate and cyclia loads. Simplified relationships for practicaι desiμ are given. 1 ΙNTRoDUcTΙoN Ιn modem earthquake design of steel struοfuΙes, iηelastic excursions of members and rcdistribution of intemal actioηs are permifted when the stnΙcture undergoes seveΙe seismic actions, Ιn this conlext, the condition for a struοtuΓe to avoid collapse is that the memb€ rs sustaining pιastic deformation should possess avaiΙabιe ductility gτeater than ductility requirements, So, the aνailable ductiΙiξ, of sιructιιΙal οomponents is a very importanl parameter in seismiο design, but despite of...
The inelastic behaviour of structures strongly depends on the type of earthquake excitation. Moreover the ductility, both the local and global one, as well as the associated strength is depending on the loading history and the rate of loading. The engineering community, starting from the San Fernando earthquake, USA 1971, the Michoacan seismic event, Mexico City, 1985, and further to the Northridge, 1994, USA, and Kobe, 1995, Japan, earthquakes, well recognized and classified the differences between the far source and near source seismic excitations. This paper, through a review of existing literature, is focused upon the effect of both the different loading history and the loading rate on the capacity of steel members. It attempts to provide information in order to reconsider the way of approaching the prediction of the inelastic capacity of steel members.
Part of the energy of a severe earthquake shock is absorbed by the inelastic deformation of the structural frame. In order to assess the inelastic deformability of a steel frame, it is necessary to know the load-deformation behavior of its components. The inelastic loaddeformation response of, beams, beam-columns and beam-and-column 8ubassemblages ,which are subjected to static uni-directional loading is examined. The response criterion for a member is the end moment-end rotation relationship. It is shown, both from experimental and theore-tical~onsiderations, that the inelastic load-deformation behavior of wide-flange steel frames and frame components can be predicted and that therefore the energy absorption capacity of these frames can be assessed.
Probabilistic assessment of ductility for earthquake resistant design of steel members
Journal of Constructional Steel Research, 1999
An appropriate supply of member ductility is an important ingredient for successful earthquake resistant design since it enables the primary objective of a well controlled dissipative collapse mode to be realised, without excessive strength requirements being imposed on nondissipative components. As with other performance criteria, uncertainties influence the actual ductility supply, with material variability being a key contributor. This paper examines the effect of this variability on cantilever tip deflection ductility, based on an interactive local buckling model developed for steel members subjected to large inelastic excursions. Probabilistic models for yield stress and strain hardening variability are introduced in a FORM reliability analysis, and their influence studied for a wide range of steel beam and column members. The results quantify material variability on member response, and are readily presented for design use through the definition of generalised parameters involving cross-section properties and material uncertainty coefficients.
Structure and Mechanical Properties of High-Strength Structural Steels
Structure and Mechanical Properties of High-Strength Structural Steels, 2018
The structure and the mechanical properties of the high-strength structural martensitic steels used in manufacturing the mechanism parts subjected to significant cyclic dynamical loads are considered. All the steels have a similar martensitic-bainite structure and a high stability of their mechanical properties. At the same time, their structures are found to contain secondary phases, which can degrade their functional properties. 03Kh11N10M2T maraging steel exhibits fairly high impact toughness for this class of steels despite a brittle character of fracture during bending impact tests.
Constitutive Relation And Failure Criterion For Three Structural Steels At High Strain Rates
Sustainability, 2002
The effects of strain rate, temperature and stress triaxiality on strength and ductility are studied for the three structural steels Weidox 460 E, Weldox 700 E and Weldox 900 E. The material properties are obtained from three types of tensile tests: quasi-static tests with smooth and notched specimens, quasi-static tests at elevated temperatures and dynamic tests over a wide range of strain rates. The test data are used to determine material constants for constitutive relations and fracture criteria for the three steels.
Stability and ductility of steel elements
Journal of Constructional Steel Research, 1997
This paper presents a method for the simulation of the behaviour of steel structural elements both before and after the attainment of the ultimate load. It is based on a strain-oriented formulation of the governing relations usually applied to stability problems. Accordingly, the response of elements subjected to specific strain conditions is determined. Several types of elements, including single plate panels, transversely loaded beams, axially loaded columns and compressed stiffened plates with imperfections, are investigated. The analytical results are compared with experimental ones. Various modes of failure with different characteristics in the post-critical region are detected. The elements examined show that if bending and plate buckling prevail, the failure mode is ductile, while in the case of global buckling and lateral torsional buckling, a nonductile failure is expected. The method may serve for both stability and ductility evaluations of steel elements, which are needed if the design format includes a direct comparison between ductility supply and ductility demand for structural elements.
New proposal for classification of steel flexural members based on member ductility
Classification of cross-section is an important concept in the design of flexural steel members as it addresses the susceptibility of a cross-section to local buckling and defines its appropriate design resistance. In fact the section ductility concept is employed in the most of current steel design codes where section behavior is governed by the buckling of flange or web plates, for which independent limitations are imposed. This assumption is unreasonable because, obviously, the flange is restrained by the web and the web is restrained by the flanges, so the interaction between the two local buckling modes must be considered. Furthermore at the member level, there are some additional factors that influence the ductility (e.g. the beam span, flange to web width ratio, member slenderness, moment gradient, etc). As a consequence of these factors, it seems that the section behavioral classes should be substituted by the concept of member behavioral classes. The present study employs experimentally verified nonlinear finite element modeling techniques for the study of classification based on member ductility. Attention is given to the interaction between local and lateral buckling of I-sections and their influence on inelastic flexural ductility for members subjected to a constant moment. To determine the member rotation capacity for uniform moment loading, a new equivalent method was proposed. An extensive parametric study was carried out on welded beams with I-cross sections. The results illustrate that there are great differences between the two classification criteria presented and that the member classification is more appropriate for checking the structural ductility than the cross-sectional classes. On this basis a new proposal for a possible classification is made based on member ductility with taking into account the interaction between local and local-overall buckling modes.
Ductility limits of high strength steels
2016
The paper presents an automated numerical method for acquiring true stress-strain relationship from the material test results of high-strength steels. The model beyond uniform load is iterated to produce load-displacement relationship matching the experimental results recalculated by finite element method. We have used this approach to evaluate coupon tests of high-strength grades S700 and S960, and extended the study to mild steels S275 and S355 for comparison. The results were validated against the tensile experiments of plates with central hole made from the same steel S960 as original coupons. The presented algorithm will serve as a basis for evaluation of ductility limits for different steel grades.