Modeling of the nonlinear behavior of semi-rigid connections in steel framed structures and its influence on three dimensional analysis of structural systems

Download
2019
Özel, Halil Fırat
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. The proposed element formulation can accurately capture the spread of plasticity along element length and section depth with a single element for each beam and column member. Introducing flexible connections to frame members does not necessitate additional nodes where the degrees of freedom do not increase. Also, nonlinear geometric effects and a correct shear area definition are applied to the elements with the use of the proposed element. Accuracy and robustness of the proposed element are presented at both member level and structural level for both the two-dimensional and three-dimensional rigid and semi-rigid steel frame structures. Verifications are conducted by considering studies presented in the literature, as well as the results obtained using advanced nonlinear finite element programs.

Suggestions

Modeling of the nonlinear behavior of steel framed structures with semi rigid connections
Sarıtaş, Afşin; Özel, Halil Fırat (null; 2015-07-21)
A mixed formulation frame finite element with internal semi-rigid connections is presented for the nonlinear analysis of steel structures. Proposed element provides accurate responses for spread of inelasticity along element length by monitoring the nonlinear responses of several crosssections, where spread of inelasticity over each section is captured with fiber discretization. Each material point on the section considers inelastic coupling between normal stress and shear stress. The formulation of the ele...
Consistent matrices for steel framed structures with semi-rigid connections accounting for shear deformation and rotary inertia effects
ÖZEL, HALİL FIRAT; Sarıtaş, Afşin; Tasbahji, Tayseer (2017-04-15)
Estimation of vibration characteristics and thus the seismic loads acted on steel framed structures are influenced by the presence of semi-rigid connections and accurate modeling of shear deformations and rotary inertia effects. This paper presents a finite element model that takes into account all these effects in order to calculate consistent stiffness and mass matrices. The formulation of the element utilizes three fields Hu-Washizu-Barr principle, where the need for displacement shape function approxima...
An Accurate modeling approach for calculating the vibration characteristics of steel framed structures with semi rigid connections
Özel, Halil Fırat; Sarıtaş, Afşin (null; 2015-07-01)
Vibration characteristics of steel framed structures are affected by the presence of semi-rigid connections. In this study, a mixed formulation frame finite element is developed from force method, where the variational form of the element bases on the use of three-fields Hu-Washizu-Barr principle. Consistent mass matrix of the element is obtained such that determination of vibration frequencies of members with varying geometry and material distribution as well as the presence of semi-rigid connections at an...
Vibration characteristics of various wide flange steel beams and columns
Özel, Halil Fırat; Sarıtaş, Afşin; Tasbahjı, Tayseer (null; 2015-12-11)
Vibration characteristics of steel framed structures are affected by accurate modelling of the mass and stiffness matrices of beam and column members. In this regards, wide flange sections are the most popularly used steel sections, and calculation of axial, flexural and shear responses of these sections become critical. In this study, a mixed formulation frame finite element is developed from three-fields Hu-Washizu-Barr functional. Consistent mass matrix of the element is obtained such that determination ...
Stability of beams in steel eccentrically braced frames
Yigitsoy, Gul; Topkaya, Cem; Okazaki, Taichiro (2014-05-01)
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 ...
Citation Formats
H. F. Özel, “Modeling of the nonlinear behavior of semi-rigid connections in steel framed structures and its influence on three dimensional analysis of structural systems,” Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Civil Engineering., Middle East Technical University, 2019.