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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 91
Edited by: B.H.V. Topping, L.F. Costa Neves and R.C. Barros
Paper 9

The Influence of the Semi-rigid Behaviour of Column Base Plates and Beam-to-Column Joints on the Non-linear Dynamical Response of Steel Portal Frames

F. da R. de C. Lopes1, J.G.S. da Silva2, P.C.G. da S. Vellasco3, L.R.O. de Lima3 and L.F. da C. Neves4

1Civil Engineering Post-graduate Programme (PGECIV),
2Mechanical Engineering Department, 3Structural Engineering Department,
State University of Rio de Janeiro (UERJ), Brazil
4ISISE, Civil Engineering Department, University of Coimbra, Portugal

Full Bibliographic Reference for this paper
F. da R. de C. Lopes, J.G.S. da Silva, P.C.G. da S. Vellasco, L.R.O. de Lima, L.F. da C. Neves, "The Influence of the Semi-rigid Behaviour of Column Base Plates and Beam-to-Column Joints on the Non-linear Dynamical Response of Steel Portal Frames", in B.H.V. Topping, L.F. Costa Neves, R.C. Barros, (Editors), "Proceedings of the Twelfth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 9, 2009. doi:10.4203/ccp.91.9
Keywords: beam-to-column connections, non-linear analysis, dynamic analysis, column base plates, semi-rigid behaviour.

It is well known that the steel portal frame design assumes that beam-to-column connections are rigid or pinned. Rigid connections, where no relative rotations occur between the connected members, transfer not only a significant amount of bending moments, but also shear and axial forces. On the other extreme, pinned connections are characterized by almost free rotation movement between the connected elements that prevents the bending moment transmission.

Despite these facts, it is largely recognized that the great majority of joints does not exhibit such idealized behaviour. These connections are called semi-rigid, and their design should be performed according to their actual structural behaviour. Numerous studies were made on composite and steel semi-rigid connections including: state of the art reports, numerical studies and experimental tests [1,2,3].

One of the main objectives of this study is to propose an analysis methodology to properly represent the influence of the semi-rigid behaviour of base plates and beam-to-column joints on the dynamical response of steel structures (linear and non-linear). Another important investigated issue concerned the assessment of the steel frames dynamical behaviour (linear and non-linear) due to the presence of symmetrical and non-symmetrical beam-to-column semi-rigid joints and, especially, the column base plates.

The structural analysis was made with the aid of the ANSYS [4] finite element program. The finite element model included geometric non-linearity, column base plates and beam-to-column non-linear behaviour and considered the influence of non-linear and hysteretic moment versus rotation curve of the joints.

The results indicated that the resonance physical phenomenon was not reached in the nonlinear semi-rigid frames dynamic response. The resonance did not occur in these systems due to the hysteretic damping induced by the energy dissipation of the non-linear hysteretic loops at the non-linear joints. The hysteretic damping can not also be observed in simple linear stiffness joint models and emphasized the important damping character developed in non-linear hysteretic joints.

F. da R. de C. Lopes, "Influência do Comportamento Semi-Rígido de Placas de Base e de Ligações Viga-Coluna na Resposta Dinâmica de Pórticos de Aço", MSc Dissertation (In Portuguese), Post-graduate Programme in Civil Engineering, State University of Rio de Janeiro, UERJ, Rio de Janeiro, Brazil, 2008.
J.P. Jaspart, D. Vandegans, "Application of the Component Method to Column Bases", Journal of Construction Steel Research, Vol. 48, pp 89-106, 1998. doi:10.1016/S0143-974X(98)90196-1
P.P.T. Chui, S.L. Chan, "Transient Response of Moment-Resistant Steel Frames with Flexible and Hysteretic Joints", Journal of Constructional Steel Research, Vol. 39, pp. 221-243, 1996. doi:10.1016/S0143-974X(96)00038-7
ANSYS, Swanson Analysis Systems, Inc., P.O. Box 65, Johnson Road, Houston, PA, 15342-0065, Version 10.0, Basic analysis procedures, 2nd edition, 2003.

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