Stability of beams in steel eccentrically braced frames

Yigitsoy, Gul
Topkaya, Cem
Okazaki, Taichiro
When an eccentrically braced frame (EBF) is subjected to a severe seismic event, large axial force and bending moments are produced in the beam outside of the link Designers face significant difficulties in meeting the capacity design requirement to keep these beams elastic. On the other hand, previous research suggests that controlled yielding in the beams is not detrimental to EBF performance as long as stability of the beam is maintained. A computational study was undertaken to investigate the stability of cyclically loaded EBFs. A total of 51 EBF sub-assemblage models, none of which satisfies the capacity design requirement, were selected and investigated through three-dimensional, nonlinear finite element analysis. The results indicate that the link overstrength factor should be a function of the link length for performing capacity design of the beam outside of the link This is because flexure yielding links, which are more problematic to beam stability, tend to develop smaller overstrength compared to shear yielding links. Furthermore, designs with demand-to-capacity ratios greater than unity were found to be viable provided that the stability of the beam is maintained by making use of a slenderness limit developed herein.


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Inelastic deformation capacity of links is a factor that significantly influences design of steel eccentrically braced frames (EBFs). The link rotation angle is used to describe inelastic link deformation. The link rotation angle is generally calculated by making use of design story drifts that in turn are calculated by modifying the elastic displacements by a displacement amplification factor. This paper presents a numerical study undertaken to evaluate the displacement amplification factor given in ASCE7-...
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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
G. Yigitsoy, C. Topkaya, and T. Okazaki, “Stability of beams in steel eccentrically braced frames,” JOURNAL OF CONSTRUCTIONAL STEEL RESEARCH, pp. 14–25, 2014, Accessed: 00, 2020. [Online]. Available: