Structural assessment of minor axis steel joints using photoelasticity and finite elements (original) (raw)
Related papers
International Journal of Mechanical Sciences, 2002
This paper describes a series of experimental tests followed by ÿnite element simulations produced to enable the prediction of moment resistance and rotation capacity of minor axis beam-to-column semi-rigid connections. These investigations motivated the development of a mechanical model to assess the connection's structural response. The mechanical model is based on the component method of design, in accordance with the Eurocode 3 speciÿcation. This philosophy implies that each joint component is represented by a spring possessing a non-linear force versus displacement (F-) curve. The model was subsequently calibrated against experimental and ÿnite element results previously performed.
Steel beam-to-column joints are often subjected to a combination of bending and axial forces. Alternatively, significant axial forces can also be present at the joint in cases like: pitched-roof portal frames, sway frames or frames with partially constructed floors. Despite this fact, only very simplified design procedures are available for the analysis and design of beam-to-column joints under these actions. A single empirical limitation to the applied axial force of 5% of the beam plastic resistance under axial force is the only enforced provision present in the Eurocode 3 [1]. The main purpose of the present paper is to describe a numerical investigation developed to fully characterize the structural response of endplate beam-to-column joints subjected to bending and axial forces. Experimental results, carried out at the University of Coimbra, Portugal, were used to calibrate the finite element model. These analyses were focused on expanding the test results and enabling a complete understanding of the structural behaviour of this particular type of semi-rigid connections.
An assessment of beam-to-column endplate and baseplate joints including the axial-moment interaction
Knowledge of the moment-rotation characteristic of connections is an essential prerequisite for use of the so called semi-continuous approach to steel and composite frame design. Although the axial force transferred from the beam is frequently low, so that its effect on the moment-rotation characteristic may often be neglect, certain circumstances do exist in which axial compression or tension forces will be sufficiently large that it is no longer reasonable to ignore their influence. Relatively few experimental results have been reported to investigate this effect. A method is presented herein which extends the range of application of available data so as to produce moment-rotation characteristics that implicitly make proper allowance for the presence of significant levels of either tension of compression in the beam. The method depends directly on the availability of a limited amount of data but then uses a corrective process to permit the full range to be covered. The applicably and validity of the proposed methodology is demonstrated through comparisons against several tests on both flush end-plate joints and base plate arrangements.
Engineering Structures, 2004
Steel beam-to-column joints are often subjected to a combination of bending moment and axial force. Current specifications for steel joints do not take into account the presence of axial forces (tension and/or compression) in the joints. A single empirical limitation of 5% of the beam's plastic axial capacity is the only enforced provision in Eurocode 3-Part 1.8. The objective of the present paper is to describe an experimental program carried out at the University of Coimbra on extended endplate beam-to-column joints to try to extend the component method philosophy to the combined action of bending moment and axial force. To fulfil this objective, a set of seven extended beam-to-column joints were tested. This paper provides a detailed description of this experimental programme focusing on the moment-rotation curves and individual component assessment. Finally, it reveals that the presence of an axial force on the beam significantly modifies the joint response.
Numerical Analysis of Endplate Beam-To-Column Joints Under Bending and Axial Force
2010
Steel beam-to-column joints are often subjected to a combination of bending and axial forces. Alternatively, significant axial forces can also be present at the joint in cases like: pitched-roof portal frames, sway frames or frames with partially constructed floors. Despite this fact, only very simplified design procedures are available for the analysis and design of beam-to-column joints under these actions. A single empirical limitation to the applied axial force of 5% of the beam plastic resistance under axial force is the only enforced provision present in the Eurocode 3 (1). The main purpose of the present paper is to describe a numerical investigation developed to fully characterize the structural response of endplate beam-to-column joints subjected to bending and axial forces. Experimental results, carried out at the University of Coimbra, Portugal, were used to calibrate the finite element model. These analyses were focused on expanding the test results and enabling a comple...
Review on the modelling of joint behaviour in steel frames
Journal of Constructional Steel Research, 2011
Steel portal frames were traditionally designed assuming that beam-to-column joints are ideally pinned or fully rigid. This simplifies the analysis and structural design processes, but at the expense of not obtaining a detailed understanding of the behaviour of the joints, which in reality, have finite stiffness and are therefore semi-rigid. The last century saw the evolution of analysis methods of semi-rigid joints, from the slope-deflection equation and moment distribution methods, to matrix stiffness methods and, at present, to iterative methods coupling the global and joint structural analyses. Studies agree that in frame analysis, joint rotational behaviour should be considered. This is usually done by using the moment-rotation curve. Models such as analytical, empirical, experimental, informational, mechanical and numerical can be used to determine joint mechanical behaviour. The most popular is the mechanical model, with several variances (e.g. Component Method). A summary is given of the advantages and disadvantages and principal characteristics of each model. Joint behaviour must be modelled when analysing semi-rigid frames, which is associated with a mathematical model of the moment-rotation curve. Depending on the type of structural analysis required, any moment-rotation curve representation can be used; these include linear, bilinear, multilinear and nonlinear representations. The most accurate representation uses continuous nonlinear functions, although the multilinear representation is commonly used for mechanical models. This article reviews three areas of steel joint research: (1) analysis methods of semi-rigid joints; (2) prediction methods for the mechanical behaviour of joints; (3) mathematical representations of the moment-rotation curve.
Experimental behaviour of 3D end-plate beam-to-column bolted steel joints
Engineering Structures, 2019
This work presents the experimental assessment of the joint behaviour of five steel beam-to-column end-plate joint configurations to assess (i) the effect of minor axis end plate joints in the behaviour of major axis end plate joints, and (ii) the interaction of two minor axis end plate joints. The experimental tests were performed with true size cruciform sub-frames specimens with boundary conditions intended to simulate unbraced frames. The sub-fames, with one to three beams, were loaded introducing multiple 3D stress states in the column unstiffened web, causing an interaction between the mechanical behaviour of two or three major and minor axis joints. The interactions were assessed in terms of the moment-rotation relations of joints, connections and column web. It was found that, for the slenderness of the column web tested, (i) the minor-axis joints have only a relevant influence on the stiffnesses of the major-axis joints and (ii) that, when two minor axis joints are present, their mutual interation increases both their stiffness and strength.
Post-limit stiffness and ductility of end-plate beam-to-column steel joints
Computers & Structures, 2002
A procedure for the evaluation of ductility in steel joints is presented. Using the component method as background, a non-linear analysis for a number of end-plate beam-to-column joints is performed that is capable of identifying the ''yield'' sequence of the various components and the failure of the joint. Each component is characterised using a bilinear approximation for the force-displacement relation. Comparing these results with the corresponding experimental results leads to a proposal of the post-limit stiffness of the various components. A component ductility index is proposed for each component as a means of classification with respect to ductility, using the three ductility classes currently proposed in the literature. A joint ductility index is also proposed, which can be used to verify available rotation against the structure required rotation. Ó
An analytical evaluation of the response of steel joints under bending and axial force
Computers & Structures, 2001
This paper presents an equivalent elastic model where each bi-linear spring is replaced by two equivalent elastic springs using an energy formulation and in the context of a post-buckling stability analysis. Such a model yields analytical solutions for the evaluation of the behaviour of steel joints under compressive forces, combined axial force and bending moment, which enables the reproduction of their full non-linear behaviour. The resulting formulation is applied to a simple beam-to-column welded connection initially loaded in pure compression. Subsequent loading of the joint in combined bending and various levels of axial force clearly shows the reduction in moment capacity.