A Parametric study on the influence of semi-rigid connection nonlinearity on steel special moment frames

Metin, Tolga
In practice, steel frames are analyzed and designed by assuming all beam to column connections as either rigid or simple. In real life, there are no such idealizations as rigid or simple and all connections would actually belong to a group of connections named as semi rigid connections. Various difficulties exist in modeling an accurate non-linear behavior of a steel structure, where one of these challenges is the modeling of semi-rigid behavior of connections. A detailed finite element model would take into account the complex interaction between all surfaces due to contact, friction and bolt pretension besides the material and geometrical nonlinearity effects. All these nonlinearity effects could be simply lumped as a moment-rotation type model at the connection region. Such a methodology is followed in this thesis and the main aim is to study the lumped nonlinear behavior of steel semi-rigid connections on the overall structural responses of steel Special Moment Frames. In this thesis three, nine and fifteen story steel Special Moment Frames are analyzed and designed as rigid frames first, and then the frames are reanalyzed considering non-linear effects due to semi-rigid connections. Changes in the ductility and overstrength reduction factors obtained from pushover curves are compared between the rigid and semi rigid modeling alternatives.


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Azap, Nurettin Murat; Sarıtaş, Afşin; Department of Civil Engineering (2013)
In steel structural systems, beam to column connections are usually assumed either rigid or pinned in practice. In reality rigid connections have some flexibility and shear connections have some rigidity incorporated in their real behavior with significant nonlinearity included, as well; thus this behavior results into the categorization of some connections as semi-rigid. Beam to column connection regions contain one or more of the following components: angles, plates, welds, and bolts. Understanding the ph...
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Köseoğlu, Ahmet; Sarıtaş, Afşin; Department of Civil Engineering (2013)
In the analyses of steel framed structures it is customary to assume the beam to column connections as either fully rigid which means that all moments are transferred from beam to column with negligible rotation or ideally pinned that resists negligible moment. This assumption is reasonable for some types of connections. However when considering steel connections such as bolted-bolted double web angle connections it can be seen that the behavior of these connections is in between the two extreme cases. Thus...
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The restraint provided by elastomeric bearings to frames is rarely taken into account in frame stability design. If taken into account, then the consideration that the restraint they introduce might influence sway condition of the frame makes it harder to classify the frame as braced or unbraced .Conventional methods of stability analysis, e. g the Effective Length Method(ELM), which relies on such a classification, can not be readily applied in its analysis, and advanced or more general methods such as the...
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Mörel, Osman Fuat; Yılmaz, Çetin; Department of Civil Engineering (2004)
In this study two dimensional steel frames, reinforced with un-stiffened thin steel panels, are investigated. In the first part of the study, the strip model, a method for analyzing un-stiffened thin steel plate shear walls, was investigated. Sensitivity studies to investigate the influence of the number of strip members to be used to in the strip model and their angle of inclination were conducted. In the second part, responses of various un-stiffened steel plate shear wall systems to lateral loads were in...
Modeling of the nonlinear behavior of semi-rigid connections in steel framed structures and its influence on three dimensional analysis of structural systems
Özel, Halil Fırat; Sarıtaş, Afşin; Department of Civil Engineering (2019)
In steel frame structures, introducing the nonlinear force-deformation behavior of frame members with flexible joints will show closer results to the actual behavior. In this thesis, a mixed formulation frame finite element is developed from a nonlinear force-based method that can include localized semi-rigid connection response. The formulation of the element uses the three-fields Hu-Washizu-Barr principle, where displacement shape function approximation is omitted with the use of a force-based approach. T...
Citation Formats
T. Metin, “A Parametric study on the influence of semi-rigid connection nonlinearity on steel special moment frames,” M.S. - Master of Science, Middle East Technical University, 2013.